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RoilElectronicComponents

FEBRUARY 1975, ELECTRONIC TECHNICIAN/DEALER I 1

J. W. PHIPPSEditor1 East First StreetDuluth, Minn. 55802(218) 727-8511

ALFRED A. MENEGUSPublisher757 Third AvenueNew York, N.Y. 10017(212) 754-4382

TOM GRENEYPublishing Director

JOSEPH ZAUHARManaging Editor

S. J. SMITHProduction Manager

JOHN PASZAKGraphic Design

LILLIE PEARSONCirculation Fulfillment

GENE BAILEYManager, Reader Services

CONTRIBUTING EDITORS

JOSEPH J. CARRBERNARD B. DAIEN

MANAGERS

DAVE HAGELIN43 East Ohio StreetChicago, Ill. 60611(312) 467-0670

CHUCK CUMMINGSAd Space South/West613 North O'ConnorIrving, Texas 75060(214) 253-8678

KEN JORDANDONALD D. HOUSTON1901 West 8th StreetLos Angeles, Calif. 90057(213) 483-8530

CHARLES S. HARRISONCY JOBSON57 Post StreetSan Francisco, Calif.94104(415) 392-6794

ROBERT UPTONTokyo, JapanC.P.O., Box 1717

ELECTRONICTECHNICIAN/DEALERFEBRUARY 1975 VOLUME 97 NUMBER 2

THE COVER: Close-up photo which shows how the electron gun of a color TV picture tubeis sealed into the neck of the tube during manufacture. Courtesy of GTE Sylvania.

FEATURES

12 TRANSISTOR BETA-A PERSPECTIVE FOR SERVICE TECHNICIANS

How transistor gain affects and is affected by the freqency response, biasing, inputimpedance and switching requirements of circuits. By Bernard B. Daien, ET/D Con-tributing Editor.

20 ISOLATING CHROMA TROUBLES IN SYNCHRONOUS DIODE

CHROMA DEMODULATOR SYSTEMS

Theory of operation of a representative design, and how to interpret and isolate thecauses of typical trouble symptoms. By Joseph Zauhar, ET/D Managing Editor.

24 DIGITAL FREQUENCY COUNTERS FOR SERVICING-PART 2

How to use digital counters to check the frequency of communications transmitters,to calibrate test instrument, to adjust tape recorder motor speed, and to performservicing -related checks of various other consumer electronic products. By JosephJ. Carr, ET/D Contributing Editor.

28 NEW IN COLOR TV FOR 1915-PART 6

A look at the new and significantly changed features and circuits in GTE Sylvania'slatest color TV chassis. By Joseph Zauhar, ET/D Managing Editor.

32 TECH BOOK DIGEST-Troubleshooting Horizontal Deflection &High -Voltage Circuits-Part 2

Techniques for isolating troubles in horizontal output and high -voltage rectifier andregulator circuits. By Ben Gaddis, TAB BOOKS, Copyright 1974.

53 TEKFAX-Airline b -w TV Models GAI-11115A, B and GAI.11155A, B; Airline colorTV Models GAI-12103B; General Electric color TV Ch. MB -75; Sylvania b -w TV Ch.A19-1, -2; and Sylvania color TV Ch. D16-3 thru -9.

DEPARTMENTS

4 PUBLISHER'S MEMO 38 TEST INSTRUMENT REPORT

6 LETTERS 41 NEW PRODUCTS

8 NEWS OF THE INDUSTRY 44 DEALER SHOWCASE

10 TECHNICAL LITERATURE 48 CLASSIFIED ADS

11 ELECTRONIC ASSOCIATION DIGEST 50 ADVERTISERS' INDEX

36 TECH DIGEST 51 READER SERVICE

fEr.'11]' A HARCOURT BRACE JOVANOVICH PUBLICATION 7167 472)

ELECTRONIC TECHNICIAN/DEALER is published monthly by Harcourt Brace Jovanovich Publications.Corporate offices: 757 Third Avenue, New York, New York 10017. Advertising offices: 43 East OhioStreet, Chicago, Illinois 60611 and 757 Third Avenue, New York, New York 10017. Editorial, Ac-counting, Advertising Production and Circulation offices: 1 East First Street, Duluth, Minnesota55802. Subscription rate: one year, $7; two years, $12; three years, $16 in the United States andCanada. Other countries: one year, $15; two years, $24; three years, $30. Single copies: 75C inthe U.S. and Canada; all other countries: $2. Second Class postage paid at Duluth, Minnesota55806 and at additional mailing offices. Copyright @ 1975 by Harcourt Brace Jovanovich, Inc. Allrights reserved. No part of this publication may be reproduced or transmitted in any form or byany means, electronic or mechanical, including photocopy, recording, or any information storageand retrieval system, without permission in writing from the publisher.POSTMASTER: Send Form 3579 to ELECTRONIC TECHNICIAN/DEALER, P.O. Box 6016, Duluth, Minne-sota 55806.

2 ELECTRONIC TECHNICIAN/DEALER, FEBRUARY 1975

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DURACELL' . DURATAPE' and SONALERT ' are registered trademarks of P. R Mallory & Co. Inc.

. . . for more details circle 113 on Reader Service Card

FEBRUARY 1975, ELECTRONIC TECHNICIAN/DEALER 3

PUBLISHER'S MEMO

MANUFACTURERS GEAR UP FOR 1975

At the National Convention ofthe Association of Electronic Man-ufacturers (AEM), held in Miami,Fla., last November, the distribu-tors gathered there heard of someimportant developments in theelectronics industry which shouldbe of considerable interest to thethousands of readers of ELEC-TRONIC TECHNICIAN/DEALER.

The merger of the AEM with theDistributor Products Division(DPD) of the Electronic IndustriesAssociation (EIA) was consumma-ted at this last convention of themanufacturers' group. In his com-ments after the merger signing,EIA President V. J. Adduci notedthat "we have greatly strength-ened our force, not only to serveelectronic distribution, but also tohelp our industry meet its biggestchallenge: to realize the vast po-tential for growth which our tech-nology gives us."

R. W. Woodbury, President,Sprague Products Company, hasbeen elected to serve as the Divi-sion's chairman this year. ArthurF. Kelly, Jr., General Manager, Am-perex Electronic Corp., and HerbBowden, President, Sencore,

are the newly elected vice chair-men of the DPD/EIA. The mergerprovides a strong base and effec-tive representation in Washington,D.C., for the electronic manufac-turers whose equipment and com-ponents the professional electron-ic technician and service dealerpurchase as the end user. Withsuch a strong and unified front,the DPD/EIA will meet the chal-lenge of the times and help our in-dustry back to a sound economy.

Presiding at the business ses-sions were Frank Vendely, GeneralSales Manager, Mallory Distribu-tor Products Company, and AlEisenberg of the Microtran Co.

Bud Mowrey of RCA ElectronicComponents was the keynotespeaker at this convention. Execu-tives of the manufacturers whospoke at this meeting were HerbBowden, Sencore, Inc.; Al Roth,Arco; Ed Kason, Amphenol; ArtKelly, Amperex; Glenn Ronk, Sola;Howard Saltzman, Alpha Wire;Herb Taylor, Clarostat; and RoyVetzner, Vaco.

Distributors who spoke at theconvention included Jim Mc-Gowan, Kierulff; Tim Cronin, Cra-

Discussing important industry event,NEWCOM '75, while attendingAEM National Convention in Miamiwere (l -r) Al Menegus, Publisher,ELECTRONIC TECHNICIAN/DEALER; TomGreney, ET/D Publishing Directorand Vice President, Harcourt BraceJovanovich Publications; David L. Fisher,Executive Director, DPD/EIA CentralRegion; and Kenneth C. Prince,Executive Vice President, ElectronicIndustry Show Corporation.

mer; Pete Heller, Pioneer -Stan-dard; Jack Darcy, Arrow; AlCowles, Jr., Bluff City Distributingand President of the NEDA; Man-ny Grossman, Ohm; Joel Girsky,Jaco; and Tony Hamilton, Hamil-ton-Avnet. Gene Foster and BudMoulthrop discussed manufactur-er -sales rep relationships.

Drawings were made of the ex-hibit areas for the vital industryshow, NEWCOM '75, to be heldMay 6-7-8 in Las Vegas. Theme ofthis big show is the "World Seriesof Electronic Distribution." Indi-cations are that this will be thelargest show ever. According tosome economic forecasts, the na-tion's business climate will beginto show signs of considerable im-p'ovement just about mid -Maywhen this show is held.

After attending this conventionand speaking to all concernedwith the future of our industry, I

am sure the manufacturers, salesreps, distributors and large deal-ers have a great combination ofskill, experience and talent tobring about an impressive turn-around in the economy where ourirdustry is involved.


GTE Sylvania, Electronic Components Group, 100 First Avenue, Waltham, MA. 02154

Introducing

alliset onlyaTV technician

could love.Ultra -portable CK3000 Test Jig.Under 25 lbs.-easy to tote from job to job.The handle's not just for show!

Ready to use. Fully pre -tested.A complete unit including 13V in -lineslotted -mask CRT with x-rayinhibiting glass.

Accessories included :Two 70° adapters; two90° extensions; sixyoke -programmerplugs; audio leads;four convergenceballast plugs; Set -Upand InstructionManuals.

The big book. CK3000Set -Up Manual listsover 7000 models, 49brands. And we'reconstantly updatingit. Just mail theregistration card.

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TV set you'll meet.

Patented yokeprogrammers let youmatch CK3000's yoketo six differentdeflection outputs.Three for tube andhybrid, two fortransistor sweep, onefor SCR sweep.

Dual focus connec-tions. Built-inalternatefocus supply fortesting both 4.5kVand the new Black -Matrix 7.1kV.

See the CK3000 Test Jig at your Sylvania distributor's now!

GM SYLVANIAFEBRUARY 1975, ELECTRONIC TECHNICIAN/DEALER 5

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6 ELECTRONIC TECHNICIAN/DEALER, FEBRUARY

LETTERS

"Bugged TV" ExposesExposing servicing malpractices by

"bugging" TV receivers might be ex-cellent advertising for the service tech-nicians who have been proven honestby this method. Such exposes mightbuild public confidence in the servicetechnicians who have been provenhonest by the expose. But how aboutthe thousands of other technicianswho were not involved in the exposeand, consequently, did not have theopportunity to prove that they alsoare honest? . . .

In my opinion, the public wants toknow who the "good guys" are. Theyare tired of reading about only the"bad guys."

The type of expose that "putsdown" a service industry is, in myopinion, pornographic. It appeals onlyto morbid and prurient interests.Healthy people merely want to knowwho is a reasonably honest repairman.For example, from the viewpoint of aconsumer, I don't want to be told onlythat I stand a certain chance of beingcheated by an automotive mechanic.I want to know the names of the hon-est mechanics. I don't need to be toldthat there are some crooks in all typesof servicing; I already know that. . . .

Perhaps incompetence is the realvillain. A competent technician canearn a living without knowingly or un-knowingly cheating. . . .

EDWARD H. SAMPLEWaimanalo, Hawaii

Precisely what effect "bugged TV"exposes have had on the public'simage of the TV service business is, inmy opinion, difficult to assess.

Those who support such exposes tellus that their purpose is to eliminateunethical and incompetent servicers byexposing them to the public and, insome cases, to the local law enforce-ment authorities. They tell us thatpublic reaction to such exposes is fa-vorable to TV service businesses be-cause the public is grateful to and lesssuspicious of an industry which at-tempts to police itself. They also tellus that such exposes serve as an effec-tive warning to other servicers in theirarea to either "shape up or ship out."

Those who are opposed to "buggedTV" exposes argue that such exposesmerely draw public attention to theundesirables in the business and, bydoing so, give all servicers an unfav-orable public image as a result of"guilt by association." The opponentsof exposes also point out that some ofthe planners and executers of such ex-poses are more interested in the pub-licity they receive than in actually rid -

1975

ding the business of undesirables.In my opinion, TV servicers and ser-

vice associations should handle knownor suspected cases of unethical busi-ness practices and/or incompetent ser-vicing by alerting and cooperating withexisting law enforcement, judicial andconsumer protection agencies. If need-ed laws and agencies do not exist, TVservicers and service associations thenshould "encourage" their local andstate legislative bodies to introduceand pass the required laws and estab-lish whatever agencies are needed toenforce the laws effectively. Publicitygained from these types of activitieswill probably be more positive andfairer and more favorable to all ser-vice technicians than the negative ap-proach of "bugged TV" exposes.-TheEditor.

Module AvailabilityFor years, many TV manufacturers

have failed to realize that service tech-nicians must be able to go to their lo-cal distributor, get the required re-placement part and repair the set inthe same day (or at least within twoor three days). . . .

Now we have a new parts availabil-ity dilemma: modules. Most techni-cians cannot afford to tie up the capi-tal required to maintain an inventoryof modules for all brands of modularTV chassis . . . and the theory thattechnicians can solve this problem byspecializing in a few brands is unreal-istic.

I predict that any TV manufacturerwho sells modular receivers withoutassuring that the modules are imme-diately available to servicers from localdistributors is doomed. The public isalready annoyed about the higher ser-vices charges for new sets, and to haveto wait weeks while a needed moduleis being shipped either from the manu-facturer or from the manufacturer'sdistributor to their service technician'slocal distributor is more than increas-ing numbers of consumers can toler-ate.

Technician kits which contain oneof each of the modules required for aparticular chassis or brand of chassisare not realistic either (although theyare better than no kits at all). I havetoo often used one module out of sucha kit in the morning and needed thesame module in the afternoon or thenext day but, of course, was unable toobtain the module to restock the kit.

MAX GOODSTEINFlushing, N.Y.

This needed to be said, and you'vesaid it.-The Editor.

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NEWS OF THE INDUSTRY

Magnavox Recalls Six Monochrome TV ModelsThe Magnavox Consumer Electronics Company has instructed all dealers and service

personnel to stop the sale and delivery of the following models of Magnavox 19 -inch(diagonal) black -and -white portable TV receivers:

ME5140 MD5140ME5141 MD5141ME5142 MD5142

Magnavox has issued the recall because of the possibility that these models have anintermittent or loose connection which can cause "an electrical arc and create the pos-sibility of an ignition of the cabinet."

The company has advised owners of these sets to immediately unplug them and returnthem to their Magnavox dealer for free repair.

The six models were manufactured between late April, 1974 and October 14, 1974.

RCA Increases Prices of B -W and Color TV Replacement Picture TubesPrice increases averaging three to ten percent have been announced by RCA Electronic

Components for its black -and -white and color TV replacement picture tubes. The in-creases were effective December 15, 1974.

Price increases for specific RCA replacement picture tube products are: RCA HI-LITE color tubes, about five percent; RCA Colorama "A" color tubes, about ten percent;RCA Colorama regunned color tubes, about three and one-half to five percent; and RCAblack -and -white tubes, about three to five percent, with larger increases for some types.

RCA Scientists Use New Liquid Crystal Technique to View ElectronFlow Through ICs

RCA scientists have developed a simple technique for observing electron pulses flow-ing through integrated circuits (ICs), much as a biologist studies living cells under amicroscope.

The new technique employs liquid crystals similar to those used for readouts in elec-tronic watches and is valuable in pinpointing faults in integrated circuits, according toDr. George C. Cody, Director of the RCA Physical Electronics Research Laboratoryhere.

With the new RCA technique, scientists can watch the electron pulses flow through anIC and can locate operational defects by observing where the electron flow is interrupted.This is made possible by the fact that the normally clear liquid crystal reflects or refractslight when "stimulated" by electricity.

Engineers at RCA's Solid -State Division have used the new liquid crystal technique tolocate the exact points of design and fabrication failures as well as to uncover otherfaults in ICs manufactured or under design tests by RCA.

The new non-destructive technique was developed at RCA Laboratories by Dr. Don-ald J. Channin and Gerald E. Nostrand. It can be used for RCA's COSMOS ICs aswell as for bipolar and other types of ICs.

First, a surfactant and then a drop of nematic liquid crystal are placed on the surfaceof the IC. A thin glass cover plate then is put on the liquid crystal, like a contact lenson an eyeball.

The surfactant causes all the rod -like molecules in the liquid crystal to align in thesame direction. When electron pulses travel through the IC, the electric fields theycreate rotate adjacent molecules, thus changing the index of refraction of the liquidcrystal.

The IC next is placed in a conventional metallurgical microscope and illuminated bylight passed through a set of polarizers arranged so that normally none of the lightreaches the microscope's eyepiece. However, when the IC is operating, the refractive in-dex changes caused by the electrons' electric fields allow light to pass through thepolarizers, and, in effect, give the viewer a "live" picture of the pulses or signals flow-ing in the IC, Dr. Channin explained.

This technique, he added, quickly pinpoints mask defects and metalization failures.In addition, "hot spots" caused by shorts, etc., change the liquid from its crystallinestate to an isotropic one. This also affects the refractive index, thus pointing up theshorts as bright spots, as seen through the high-powered microscope.

The technique is quite useful in examining ICs undergoing life testing and in in -


vestigating other subtle problems. For example, an IC can be examined without andwith loads, to determine what the loading does to the devices's timing and where it hasan effect.

ICs can be examined at various speeds and at normal operating voltages -8 to 10volts for COSMOS circuits, and as low as 2 or 3 volts for bipolars.

Zenith Closes Down Lansdale, Pa., Color CRT Plant IndefinitelyZenith Radio Corporation has announced that its Lansdale, Pennsylvania, color TV

picture tube facility will be closed down indefinitely.The plant, which was first closed down in late December for year-end inventory, was

previously scheduled for reopening in early January.The company said that the Lansdale plant has been closed indefinitely because of

"a significant reduction in consumer demand for color TV receivers as a result of thecurrent recession, and TV industry manufacturing realignments which have reduced thepotential for sale of Zenith's color picture tubes to other TV manufacturers."

TV Sales to Dealers Off 13.8 Percent During First Eleven Months of 1974Total TV receiver sales to dealers during the first eleven months of 1974 were 13.8

percent below the volume for the same period in 1973.Color TV sales to dealers during the eleven -month period were down 13.6 percent

from sales during the same period for the previous year, and black -and -white TV saleswere down 14 percent.

These and other consumer electronic sales to dealers are revealed in the followingstatistics compiled and reported by the Marketing Services Department of the ElectronicIndustries Association (EIA):

TOTAL U.S. MARKET STATISTICSSALES TO DEALERS

NOVEMBER 1974 VS. NOVEMBER 1973(In Units)

FIRST ELEVEN MONTHS

1974 1973 CHANGETELEVISION

Monochrome 5,343,057 6,215,341 -14.0Color 7,095,127 8,211,821 -13.6TOTAL TELEVISION 12,438,184 14,427,162 -13.8

RADIOAM 10,880,932 14,711,301 -26.0FM 17,422,034 16,446,039 + 5.9TOTAL 28,302,966 31,157,340 - 9.2AUTOMOBILE 9,695,515 11,430,723 -15.2TOTAL RADIO 37,998,481 42,588,063 -10.8

PHONOGRAPHPortable & Table* 3,835,215 5,005,840 -23.4Console 707,493 769,362 - 8.0TOTAL PHONOGRAPH 4,542,708 5,775,202 -21.3

* Includes compact and component systems.

NFIB Survey Reveals Small Independents Also Are Visited by OSHA AgentsDuring the month of November, 3.3 percent of independent businesses with an annual

volume of $50,000 or less who responded to the continuous field survey of the NationalFederation of Independent Business (NFIB) reported that they had been inspected nyOccupational Safety and Health Act (OSHA) agents. Of this group, 21.8 percent saidthey were cited for violations.


TECHNICALLITERATURE

Digital MultimeterA 4 -page brochure describing their

Model 21 handheld digital multimeteris now available. The multimeter is apalm -size, 31/2 digit multimeter thatmeasures capacitance along with ACvolts, DC volts and resistance. De-signed for field or bench operation,the unit operates from four recharge-able NiCad batteries. The brochure isfully descriptive, containing featuresand illustrations of the multimeter.Price is $269. Data Technology Corp.,2700 South Fairview, Santa Ana, CA.92704.

Record Retention TimetableAn 8 -page up-to-date and revised

4th edition of the Record RetentionTimetable, a guide to the question"How long must you keep importantpapers" is now available. The guideopens into a chart which names thegovernment authorities and states thespecified time the law demands for theretention of over 170 listed office rec-ords. With this timetable and recordguide, designed and printed in two

colors and easy to read, will come athree -page article describing the actionto be taken in a paper disposal pro-gram and will include several illustrat-ed brochures showing the differentmodels of electric wastebaskets andpaper shredders that destroy officerecords efficiently. Electric WastebasketCorp., 145 West 45th Street, NewYork, NY. 10036.

SolderA complete new 8 -page catalog is

offered covering its broad line of sol-ders, flux -core solders, soldering fluxes,vapor degreasing solvents, special pur-pose chemicals, and related products.More than 50 solders and relateditems are described, to cover virtuallyall soldering requirements. Kester Sol-der, 4021 Wrightwood Ave., Chicago,IL. 60639.

Alarm EquipmentA new alarm equipment catalog,

designated the A-75, is now available.This 96 -page catalog describes and of-fers over 450 intrusion and fire alarmproducts. The broad product lines pre-sented provide a one -stop source ofsupplies for alarm installers, dealersand skilled industrial electronic and

One compact pattern generator givesEVERYTHING you need for fastcolor and monochrome servicing

Full coverage: IF, 38 - 85 MHz, 170 - 250 MHz470 - 790 MHz

Electronic tuning with five presettable channels Ten test patterns color and black and white Adjustable chroma/burstand RF amplitude Special sync, video and VTR test patterns External video and sound modulation NTSC color pattern generator ... $ 975.00 PAL version ... S 975.00

MIMR91111111199

÷I.1-ts

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The Philips PM5512 Pattern Generator is an invaluable asset when servicing oraligning black and white color TV receivers and other video equipment, such asVTR's. Its wide range of test facilities and its compact and lightweight constructionmake it suitable for use in the workshop and as a portable service instrument.Five color and five black and white test patterns are provided and these can bemodulated on an RF carrier which can be electronically tuned to almost all availableTV channels, including IF. The TV band and channel frequency are displayed bytwo small panel meters.

For additional information, contact:Philips Test & Measuring Instruments, Inc.

A NORTH AMERICAN PHILIPS COMPANY400 Crossways Park Drive Woodbury, N.Y. 11797

SPECIAL APPLICATIONS INFORMATION' HOT LINE'DIAL TOLL FREE NUMBER (800) 645-3043NEW YORK STATE, CALL COLLECT (516) 921-8880

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electrical technicians who requirealarm systems, parts and accessories.Products are described in some detailregarding application, principle ofoperation and specifications to allowskilled technicians to make the rightchoices. Eight pages of "ApplicationNotes" for alarm equipment is pre-sented. Some basic installation proced-ures are presented. Mountain West AlarmSupply Co., 4215 North 16th Street,Phoenix, AZ. 85016.

CCTV Security Equipment

A new catalog describing CCTVSecurity Equipment is now available.It contains nearly twice the items ofthe previous edition, the latest equip-ment specifications and the new priceschedule. Javelin Electronics, 6357 Ari-zona Circle, Los Angeles, CA.

Radiotron Designer's HandbookIn response to persistent demand,

a limited quantity of F. Langford -Smith's definitive text on audio andradio design, the Radiotron Designer'sHandbook, has been made available.This audio -radio classic contains 1,500pages of comprehensive vacuum tubetheory and practical application in-formation and is written in an easy -to-understand style with many illustra-tions. It contains hundreds of circuits,design aids, curves, and nomographs;2,500 references; and a comprehensive50 -page index containing over 7,000cross-referenced headings. Subjectscovered in depth in this handbook in-clude frequency voltage and poweramplifiers, speaker networks, record-ing characteristics, fidelity and distor-tion, tone compensation and tone con-trol, radio frequency amplifiers, recti-fication, regulation and filtering, AMand FM receiver design. Price $15.00a copy. RCA Commercial Engineering, Har-rison, NJ. 07029.

Security EquipmentA complete Alarm Installation Start-

er Kit is now available. The kit con-tains product information, wholesalecost, retail pricing information, salesliterature, installation instructions andmore. The Starter Kit is priced at$5.00. PLC Electronics, Inc., 39-50 Cres-cent Street, Long Island City, NY.11101.

Tools

A 16 -page catalog, No. SD -168,Tools & Fixin Things, is now available.The catalog lists problem solving toolsfor the weekend professional. It listshand tools, solderless electrical con-nectors, special fastening devices, etc.,Vaco Products Co., 510 North DearbornStreet, Chicago, IL. 60610.

... for more details circle 119 on Reader Service Card .. . for demonstration circle 120

10 ELECTRONIC TECHNIC IAN: DEALER, FEBRUARY 1975

ELECTRONICASSOCIATION DIGESTInformation about the activities of national, state and local associa-tions of electronic servicers, dealers and manufacturers. Materialfor publication in this department should be addressed to: ServiceAssociation Digest, ET D, 1 East First St., Duluth, Minn. 55802.

ISCET Rates Serviceability of Thirteen ColorTV Models

Members of the International Society of Certified Elec-tronic Technicians (ISCET) during November performedserviceability inspections of thirteen different brands oflate -model color TV receivers.

Specific design features of each receiver were evaluatedin accordance with serviceability criteria established byISCET. A receiver in which all of the evaluated designfeatures meet ISCET criteria for serviceability would beawarded the maximum 920 points, or a percentage ratingof 100.

Following are the ISCET serviceability ratings given thethirteen receivers evaluated in November:

PercentageBrand Model Rating

Panasonic CT253 75.34Sylvania CE4181W 75.11Motorola (Quasar) WL9219 73.1J. C. Penney 2878MF3831 72.43Zenith F4028W 72.29Magnavox (Not Listed) 70.97General Electric MC9220MP 67.38Admiral 525931 66.44Sears 52841960304 6.43RCA FT518WEN (XL1 00) 60.3Sony KV1920 53.14Hitachi (Not Listed) 52.9Toshiba C924BM 34.37

All of the color TV receivers for which model numbersare given have 19 -inch (diagonal) or larger picture tubes.

Design features which failed to meet ISCET serviceabil-ity criteria in many of the receivers were: back cover in-terlocks which did not match up readily; back covers whichdropped down on the picture tube neck when unfastened;model and serial numbers which were not permanently at-tached or which were illegible; inaccessible high -voltagecompartments; sharp edges on metal parts; field adjust-ments which were not labeled or whose component leadswere not labeled; tuners which could be removed only byremoving the entire chassis; excessive chassis or subassem-bly retaining devices; chassis and subassemblies whichcould not be safely operated or transported without props;unlabeled test points; and printed -circuit boards with cir-cuit patterns on only one side.

NEXT MONTH IN ET/D: Understanding Scope Specs

State of the Art of Auto Electronics

Efficient Home Call Dispatching and Routing

Semiconductor Diodes-A Perspective for Technicians

New in Zenith Color TV tor 1915

DID YOU KNOWHOT DIP GALVANIZINGCOSTS $0.20 N:rund?

No. 25G TowerSection weighs40#x 20A=$8.00

Mfg. Cost

ROHN'sNo. 20G TowerSection weighs30# x 20 =$6.00

Mfg. Cost

If you arepurchasingtowers whichare not HOT DIPGALVANIZEDyour cost shouldbe at least $8.00or $6.00 less.

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. for more details circle 124 on Reader Service Card

FEERUARY 1975, ELECTRONIC TECHNICIAN/DEALER 11

Transistor Beta -A Perspective for ServiceTechniciansBy Bernard B. Daien, Et'D Contributing Editor

An analysis of transistor gain and its

interrelationships with frequency, bias, inputimpedance and switching time

The term "beta" describes the for-ward current gain of a transistor con-nected in a common emitter circuit,as in Fig. 1. Beta is the ratio of cur-rent in the collector (output) cir-cuit to current in the base (input)circuit (Beta = Ic/Is). The largerIc is in relation to Is, the greaterthe value of beta.

Assume that R1 in Fig. 1 is ad-justed (decreased) until a currentof 1 ampere (1000 mA) is pro-duced in the collector circuit. If thecurrent in the base circuit is 100mA at this setting of R1, the betaof the transistor is 1000 mA dividedby 100 mA, or 10.

The value of beta just computedapplies only when 1000 mA of cur-rent is produced in the collector cir-cuit. Other levels of collector cur-rent will produce different values ofbeta. This is illustrated by Fig. 2,which is the gain -VS. -collector cur-rent curve of a typical power tran-sistor. Note that beta decreases ascollector current approaches zeroand also as the collector current ap-proaches the maximum current levelthe transistor can safely handle.

Actually, there are two "types"of beta. The one we have measuredusing the setup in Fig. 1 is called

Fig. 1-Simplified test setup for measuringDC beta.

the DC, or large -signal, beta and isoften referred to as HFE. The othertype is called AC, or small -signal,beta and is often referred to as Hr..(Note that large -signal beta hascapitalized letters in the subscript(ss), while small -signal beta haslower-case letters in the subscript(fe). This is one way of remember-ing which is which.)

Small -signal beta, Hr., is mea-sured by superimposing a small ACsignal on the DC bias current in Fig.1, and then measuring only the result-ing AC component in the collector(output) circuit of the transistor. Inthe absence of signal, a transistorhas only a DC output current whichis produced by the forward inputbias needed to "turn on" the tran-sistor. (A transistor is cut off with-out forward bias.) When a varying(AC) signal is applied to the base(input) circuit, it "swings" the col-lector current up and down aroundthe DC operating point.

HOW FREQUENCYAFFECTS BETA

The small -signal current gain andlarge -signal current gain may bequite different, especially at high

DC CURRENT GAIN100

70

50

30

20

10

7.0

5.00.01 0.02 0 05 0.1 0.2 05 10 20

IC COLLECTOR CURRENT (AMP)

Fig. 2-Chart which illustrates how the DC

beta of a typical power transistor varies ac-cording to the level of collector current.

iMINII=.101111.111111111110111..IMIIMIIIMIO.1.11M1=11111IMMENE1.11111.11111.111111.11111.111MBONIIII

.11111.11.11IIIMMII11111.0111.111111

.1111111111EUREillIIMI:4111111

UP.:11111111111111111111111111111111111

mi=iM1111=MIMMESIO111111MIMMill .1IIMMIIIM1111111=M=MMEMIIIMM=MBOIIIIIME=MENIIIIIIMIIIIIMINIO111111111111111111111111 IIUUU1111UU11111UUIL II

5.0 1

signal frequencies, because gain fallsoff rapidly at the higher frequencies.Fig. 3 illustrates the variation ofsmall -signal beta (HO with fre-quency. Note that gain is relativelyconstant from DC up to the cutofffrequency, at which point it is 3 dBdown (70 percent point). Afterthat, it rolls off (decreases) at therate of 6 dB per octave (gain ishalved every time frequency isdoubled). When Hr. reaches 1, it issaid to be at a frequency of "FT".

This loss of gain as frequency in-creases is caused by several factors.Internal capacitances exist. Thecharges stored in semiconductorjunctions look like additional capac-itances. And electrons do not movethrough semiconductors at the speedof light, but at a much slower rate,producing transit time effects whichprevent rapid changes in currentfrom being "transferred" from inputto output efficiently. Finally, thereis both resistance and inductance inthe junctions and their connectingleads.

When you are thinking of substi-tuting one device for another, re-member that the beta must be speci-fied so that the device gives the re-quired gain at both the current level(HFE), and the frequency (for HOinvolved. This means the devicemust have an FT at least 10 timesthe working frequency, if it is tohave good gain. This is illustratedin Fig. 3.

HOW BETA AFFECTS BIASING

The circuit in Fig. 4 is one stageof an IF amplifier (the same prin-ciples apply to audio amplifiers aswell) which can be used to demon-strate how HFE affects biasing. R1and R2 are relatively high -value re-sistors which form a voltage dividerthat applies 3.7 volts to the base,with the base loading the voltage di-vider. Resistor R3, in series with theemitter, has 3.0 volts across it (the3.7 volts base input minus the 0.7

32

16-8-4-2 -

CUTOFF

10 20 40 80 160FREQUENCY IN MHz

Fig. 3-Chart which illustrates that AC betavaries with frequency. Note that AC beta de-creases as frequency increases.


volt base -emitter junction drop).Because the voltage drop across thebase -emitter junction is relativelyconstant, the emitter voltage will fol-low changes in the base voltage.Substituting a transistor with onewhich has lower beta will result inhigher base current, which, in turn,loads down the base voltage divider.The result is lower base voltage,lower emitter voltage, lower collec-tor current and lower gain. If thestage is part of a series -connectedsection consisting of other stages,such as AGC'd IFs or DC -coupledaudio amplifiers, the other stages inthe section will also have their volt-ages and currents upset.

Conversely, the use of a muchhigher -gain transistor or one withvery high FT also leads to problems.For example, if an audio amplifiertransistor with an FT of 400 KHz isreplaced by another transistor withan FT of 40 MHz, the stage mightoscillate at an RF frequency.

HOW BETA AFFECTSINPUT IMPEDANCE

Although you may not havethought much about it, beta affectsinput impedance, which, in turn, af-fects gain and, in the case of tunedamplifiers, also affects bandwidth.To understand this, let's look at Fig.5, which is a PNP low -frequencypower stage. Assume that we havea perfect transistor with no voltagedrops across the junctions, and per-fect meters without resistance.

With the collector power supplydisconnected and 10 volts appliedto the base -emitter junction (for-ward bias), there would be 10 voltsacross the emitter resistor (producedby the base current flowing throughit). This would produce 1 ampere ofcurrent through the emitter resistor,

Fig. 4-One stage of an IF amplifier.

as indicated by the base currentmeter.

Assume that the transistor has aFIFE of 9, and that we now connectthe collector supply so that we getnormal transistor action. For everymilliampere of base current, we willnow get 9 milliamperes of collectorcurrent. Again, the 10 volts of baseinput will produce 10 volts at theemitter; however, this time 900 mAof the emitter current will be fromthe collector, and only 100 mA willbe from the base.

Now let's look at the input (base -emitter) impedance, which is E/I.Without transistor action, we had 10volts at one ampere, or 10 ohms,which is exactly the value of theemitter resistor in the series base-emitter circuit. But with the transis-tor conducting normally from emit-ter to collector we have 10 volts atonly 0.1 ampere, or 100 ohms. Theformula to state this is "R inputequals R emitter multiplied by thefactor beta + 1," or Rin=R.(B +1).You can see that the higher thebeta, the higher the input imped-ance.

But what if the circuit did nothave an emitter resistor? Remem-ber, we have been discussing per-fect transistors, without voltagedrops. In actuality, there is alwaysresistance in the emitter junction it-self, which varys with current. Thevalue of that resistance is 26/emittercurrent (in milliamperes). Thus, ifwe had one milliampere of emittercurrent, the emitter resistance wouldbe 26 ohms, and if the transistor hada beta of 99, the input resistancewould be 2600 ohms. If there werea resistor in the emitter, the input

-20 V

Fig. 5-PNP lowfrequency power stage usedto illustrate how beta affects input impedance.

resistance would be even higher.So you can see that a high -beta

transistor has a high input resis-tance, which reduces loading on theprevious stage and on any tuned cir-cuits feeding the input. This makessense and is easily remembered be-cause you would expect a high -betatransistor to have a lower current in-put for a given output current, and alow -beta transistor to draw more in-put current for the same collectorcurrent. And more input currentmeans lower input resistance.

Substituting a high -beta transis-tor with a low -beta transistor mightmake a nonoperating circuit func-tion again, but not properly. In volt-age regulators, the regulation will beimpaired. In tuned amplifiers, thegain and frequency response will beaffected, because the Q of the inputtuned circuits will be reduced,which, in turn, increases bandwidth(reduces selectivity).

BETA IN SWITCHINGAPPLICATIONS

Linear amplifiers need enoughbeta to establish the correct operat-ing point, input impedance, etc.Usually, incorrect beta does notcause rapid failure of linear ampli-fiers. On the other hand, in powerswitching (nonlinear) applicationsadequate beta is a must to preventquick failures.

Fig. 6A is a simplified basic in-verter, with a square -wave AC out-put (Fig. 6B). The push-pull tran-sistor switches are driven by an os-cillator. The applied DC is 20 volts.Note that when the current throughone of the transistors is zero (cutoff) in Fig. 6C, the applied voltageis at maximum, as shown in Fig.

VOLTAGEWAVEFORM

SATURATIONVOLTAGE

Fig. 6-Simplified power inverter and wave-forms at collector. A) Circuit. B) Voltage wave-fcrm. C) Current waveform.


6B. Similarly, when the current is atthe maximum permitted by the loadimpedance, the collector voltage isreduced almost to zero because ofthe voltage drop across the load.The remaining small voltage iscalled the saturation voltage and iscaused by the fact that a transistoris an imperfect switch with somesmall voltage drop across it, evenwhen it is in full conduction. Notethat when the collector current ismaximum, the voltage drop acrossthe transistor is small, hence thepower dissipated is small. But thevoltage drop is small only if thetransistor is driven hard into con-duction by the input signal. How-ever, if the transistor beta is low,the input signal will not be sufficientto turn on the transistor fully, andthe voltage drop across it will belarger than normal. As a result, be-cause the current is high and thevoltage drop across the transistor islarger than normal during the "on"alternation, the amount of power(EI) dissipated by the transistor willbe excessive, and the transistor willoverheat to the point of destruction.(During the off cycle, forward cur-rent is zero and the transistor dissi-

pates little, if any, power.)Thus, it can be seen that in

switching applications it is impera-tive that the beta be sufficientlyhigh at the operating current andfrequency to insure full saturation ofthe device.

Modern TV sets are using switch-ing type circuits in the low -voltagesupply. Inverters are used in mobileradio applications. Even the lowlygolf cart now uses a duty -cyclespeed control which is a transistorswitch. You will be seeing muchmore of switching circuits now thatreasonably priced transistors whichcan perform reliably in them areavailable.

"NORMAL" BETAWhen you are seeking a replace-

ment device, you will note that "first -grade" transistors offered by majortransistor manufacturers have betasranging over a 3 to 1 spread. A de-vice may be rated, "B=50 mini-mum, 150 maximum" and, often,with "typical B = 75" thrown in.This simply means that the transis-tor manufacturer cannot sort closerwithout increasing the price. Somereceiver manufacturers, on the other

hand, to keep critical circuits withinperformance tolerances without theneed for expensive circuit design,order transistors which are sortedcloser than this. These "original re-placement" devices often are as-signed nonstandard "house num-bers" by the receiver manufacturer.For this reason, you are usually bet-ter off getting an "original replace-ment" part or one "approved" forsuch use by the manufacturer of theequipment. Zenith, for example, of-fers interchangeability informationin their own "approved" listing.Other such information is availablefrom a number of source lists whichare free for the asking. Some ofthese lists are not very accurate, somake sure they are approved by theequipment manufacturer before re-lying upon them.

In general, capacitor -or trans-former -coupled audio stages are notcritical. DC -coupled, IF, RF, andmatched -pair stages are critical.

Devices with 2N-numbers aresupposed to be directly replaceable,and usually are. Foreign numbereddevices and house numbered de-vices often are not directly replace-able.

Don't buy a rejuvenator...buy the complete picture -tube service system!For only $199*.

RED BLUE GREEN

1. Leakage and Shorts Tests/Repairs :Meters indicate simultaneously shorts orleakage in R. B. and G guns. Here, Greengun is defective.

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4. Rejuvenation Rejunevate picture tubes 5ways with the WT -333A depending ontube's condition. Meters. above. show Redgun has been restored.

When you buy the 3 -meter RCAWT -333A, you get both an accuratepicture -tube tester and a rejuvenator.The WT -333A performs a// the vitaltests and repairs you need to servicenearly 2000 picture -tube types.

Get all of these servicing essen-tials at RCA's sensible price - only$199' Buy the WT -333A from one ofthe more than 1000 authorized RCAdistributors worldwide Or. write toRCA. Harrison. N J 07029


Remember, only RCAmakes both picture tubes and

a picture -tube tester.Ours has to be good!

RCA ElectronicInstruments

14 ELECTRONIC TECHNICIAN DEALER. FEBRUARY 1975

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CET LICENSE

HANDBOOKwith Consumer Electronics,

Audio & Industrial Electronics

Options By Joseph J. Carr

276 pages 250 illustrations

Handsome, hardbound volume

Partial List of ContentsPreparing for the CET Exam

Who May Take the CET Esaminetlon-About This Study Guide-Good StudyHabits

Basic Electronic Circuits: Ohm's Law-Alternating Current-Basic ElectronicCircuits

Basic Circuit Matti: Basic Circuit MathElectronic Circuits: RC Ntworks-Rac-

tanc - Impedance - Resonance -High- and Low -Pass Filters-ElectronicCircuits

Amplifiers. Detectors and Oscillators:Amplifier Configurations-Classificationby Conduction Angle-Coupling Tech-niques-Push-Pull Operation-Oscilla-tor Circuits-AM Detectors-FM De-tectors-Power Supply Circuits-Am-plifirs, Detectors, and Oscillators

Signals and Waveforms: Amplitude Mod-ulation-Frequency Modulation-Multi-plexd Stereo on FM-Television Sig-nals-Miscellaneous Waveforms andSignals-Signals and Waveforms Usedin Electronics

A d Transmission Lines: Trans-mission Lines for TV-Antenna Designs-Antenna Measurements - Antennasand Transmission Lines

Electronic Test Equipment and Its Use:Measurements of Voltage. Current, andResistance - Signal Sources - Oscil-loscopes - Electronic Test Equipmentand Its Use

Solid -State Devices: Semiconductor Di-odes-Transistors-Field-Effect Transis-tors - Uni junction Transistors - Four -Layer Devices-Solid-Stat Devices

Components Used in Electronics: ResistorColor Code-Capacitor Color Coding-Electrolytic Capacitors - Inductors -Switches-Components Used in Elec-tronics

Monochrome Television Circuits: CathodeRay Tube-TV Receiving System-Monochrome Television Circuits

Color Television: Th Color Signal-Ver-tical and Horizontal Circuits-ColorCircuits-Color TV

Waveform Analysis: Service Scope-TVby Waveform Analysis - WaveformAnalysis

Sample CET Examination: Sample TestAnswer Key

CET Audio Option: Scope of th Exam-ination-Organization of the StereoSystem-Power Amplifiers-DistortionTests - Frequency Response - PowerMeasurement - Electromechanical De-vices-Tapes and Noise Reduction-CET Audio Option

CET Industrial Electronics Option: SCRand Triac Circuitry-Servomechanisms

-Digital Electronics-CET Industrial Elec-tronics Option

A new, complete and practical guide to moremoney and prestige through CET certification. . . featuring the first coverage of the new audioand industrial exams!

This brand-new volume is intendedas a review for anyone preparing

for a CET (Certified Electronic Tech-nician) exam (television, audio, or in-dustrial), a state or local licenseexam, or a job -entry exam. The mate-rial is arranged logically for minimumstudy time and maximum retention,and each Chapter contains questions(with answers) at the end typical ofthose appearing in the real exams. Inall, there are 538 questions and an-swers in this unique new volume.

The first few Chapters explain theadministration and scope of the CETexams, which are given by the Na-tional Electronics Association (NEA).They offer a review of simple AC andDC circuits, and include a painless"minicourse" in simple circuit math-no difficult math is required.

To prepare you for specific testquestions, various common circuits areclearly explained: filters, resonantcircuits, differentiators, etc. One Chap-ter is devoted to universal circuits us-ing tubes and transistors. Then, antic-ipating the CET exam's RF questions,

a meaty Chapter tells how AM, FM,and TV signals are shaped up andshipped out by modulators and trans-mitters. This makes the book extreme-ly practical as a reference volume aswell as a study guide.

Systematically, the text takes thereader through antennas and trans-mission lines, electronic servicingequipment, the use and application ofcommon circuit components, basic TVtheory, and troubleshooting. Thenthere is a complete guide to waveformanalysis and its use in TV trouble-shooting. You'll find this informationpriceless for day-to-day servicing-you'll refer to it again and again.

In brief, here is all the dope youneed to pass the two brand-new CETexams and qualify as an industrialand audio electronics expert-THISIS THE FIRST CET GUIDE WITHSUCH COVERAGE! A replica test,which will serve as a dry run for theCET exam, is included to help youknow you're ready for the real thing!276 pages, 289 illustrations. Hard-bound. Publisher's List Price $8.95.

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[As, TER

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Di"( 01

Ea.TT(R

Net TRANSISTOR -ELECTRONFLOW

Fig 9 7 Symbols for bipolar transistors. Fig 12-7. An example of IQ demodulation

Over 250 clearly drawn illustrations and schematics-plus easy -to -understandtext-cover scores of topics like test equipment, color TV, solid-state devices, etc.

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Isolating Chroma Troublesin Synchronous DiodeChroma Demodulator SystemsBy Joseph Zauhar

Although there are many different types

of demodulators used in color TV receivers,

they all function to separate the colorinformation contained in the I and Q sidebands

We find an increasing number ofcolor TV chassis employing syn-chronous diode chroma demodulatorsystems. The system which we willreview is quite common, employingtwo pairs of diodes producing theR -Y and B -Y color signals. TheG -Y color signal is developed byadding the - (R -Y) and -(B -Y)color signals in the color differenceamplifiers.

Before getting into the chromademodulator circuits we will brieflyreview the preceding color stages. Ablock diagram of the typical colorstages employed in a color TV re-ceiver is shown in Fig. 1.

All of the 3.58 MHz informationreceived at the first video amplifierhas been amplified, and then fed to

the demodulators unchanged, butthe burst signal is gated to syn-chronize the subcarrier generator.At this stage, it appears that no col-or information has been recovered,because the color information is stilla part of the 3.58 MHz sidebandsignal, which is composed of 3.58MHz wave components. The chro-minance signal does not contain acarrier (sideband only), and a sub-stitute carrier must be reinserted be-fore demodulation. This function isaccomplished by the subcarrier gen-erator. This substitute carrier nowpermits demodulation of the chro-minance signal.

Chroma Demodulation CircuitIn many of the new color TV

chassis we will find two identical cir-cuits used for the chroma demodula-tors: one called R -Y (red) and theother B -Y (blue). The circuits em-ploy diodes instead of transistorsand are called balanced demodula-tors, which means that in the ab-sence of a sideband (chrominance)signal, there will be zero volts output.

A simplified balanced demodula-tor circuit is shown in Fig. 2, to il-lustrate the capacitor charging cir-cuit. This circuit consists of a sec-ondary winding of the subcarriergenerator, T510, two diodes, and two20pf capacitors. The output of thedemodulator is referenced to chassisground by grounding the center tapof the transformer. The diodes willonly allow the current to flow in the

F,,,rrolx>

APC

APCDetector

OSCControl

BuntAmp

ACCHMOr

Color

ColorRilbr

From Rod,.Output Section

ACCAmp

ROutput

Output

BYOutput

CRT

Fig. 1-Block diagram of the color stages of a typicaltransistorized color TV receiver.


This automatic transistor testerworks in -circuit when others can't.

:1<rwro570s

OUT OF CIRCUIT

LEAKAGEioENTIFy

0

a.

POWERON

PRODUCT OF DYNASCAN

IN/OUT OF CIRCUIT

NPN

GOOD

PNP

Now you can avoid wasting time unsolderinggood transistors that test bad in -circuit and goodout -of -circuit because of erroneous testing. WithB&K-Precision DynapeakTM1 Transistor Tester youcan quickly determine whether a transistor isgood or bad in circuits where automatic transis-tor testers have never worked before. Low im-pedance circuits are becoming more and morecommon in TV, audio and industrial controls-andthe Dynapeak`TM' pulse testing system will let youtest transistors in these circuits which have shuntimpedances as low as 10 ohms or 50 mfd!

COMPLETE TEST IN 9 SECONDS:

You connect the leads any way, turn the switchand the rest is automatic: Pulsating audio toneand a light automatically indicate a good device.PNP or NPN determination and Germanium orSilicon identification are automatically indicatedby LED's. Leakage tests require no charts, be-cause leakage current limits are shown on themeter face for the different kinds of devices.

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... for more details circle 104 on Reader Service CardFEBRUARY 1975. ELECTRONIC TECHNICIAN/DEALER 121

direction shown by the arrow, andthen charge the capacitors with avoltage of the polarity shown in theillustration. This charging currentwill only flow at the positive peak ofthe subcarrier generator signal andin the direction shown in the illustra-tion.

In the simplified schematic of Fig.3, the demodulator load resistors andthe output terminals have been add-ed to the circuit. The load resistorsform the discharge circuit for the20pf capacitors and a voltage ma-trix.

This matrix operation is shown inFig. 4 and 5. The voltage developedat the two capacitors is shown inFig. 4 and then in Fig. 5. Batteriesare used to replace the capacitors,to illustrate the voltage develop-ment. In a sense, we have a batterywhich is center -tapped, with thenegative terminal tied to one end ofthe resistors and the positive termi-nal tied to the opposite end of theresistors. The output of the circuitis formed from the center of the re-sistors to the center tap of the bat-tery. If the voltage drop from thecenter of the resistor to ground ineither direction is added, we wouldhave an output of zero volts.

Up to this point, we discussedwhat occurs in the demodulatorwith only the subcarrier generatorsignal applied. Now we will apply achrominance signal to the circuitand restore the color information.

The waveform in Fig. 2 illustratesthe length and relative cycle time ofthe capacitor charging interval. Thischarging interval can be expressedas a "switched on" period in whichconduction can occur. The diodesare "switched off" at all other times,by either the charge on the capaci-tors or the subcarrier generator sig-nal.

As shown in Fig. 6, the chromi-nance signal is injected between thediodes. When the diodes areswitched off, the chrominance signalviews an open circuit and no signalflows; but if the diodes are switchedon by the subcarrier generator sig-nal, the influence of the chromi-nance signal causes the circuit tofunction. Suppose the chrominancesignal has a positive componentwhen the switching on time takesplace and aids the conduction of

CHARGECURRENT

T510REFERENCE

SUBCARRIER

_CHARGINGINTERVAL

REFERENCESUBCARRIER

Fig. 2-Simplified balanced demodulator c'rcult illustrating the capacitor -charging circuit

DEMODULATOROUTPUT

I0_4400404400004040

Fig. 3.-The demodulator circuit with load re-sistors added and its output received from thecenter of the potentiometer.

diode Y4 while at the same time op-poses the conduction of Y3. Capaci-tor C7 now charges to a higherpotential and capacitor C8 dis-charges to a lower potential.

If we add the potentials from thecenter of the resistors to ground ineither direction, we will have a posi-tive 5 volts output. The voltage dropacross the resistors remains con-stant.

If a negative component was con-tained in the chrominance signal atthe switched -on interval, the chargeon capacitor C7 would have in-creased and the charge on capacitorC8 decreased. The resultant signalwould then be negative.

This demodulator is capable ofresponding to phase (polarity) andamplitude variations contained inthe chrominance signal.

The second demodulator circuit isidentical except the charging inter -

10 K 2K 10K

ZERO

bo yVOLTS

i4--

bo y

--I--

0000000si0000a000i

Fig. 4-The demodulator circuit is shown inbalance, with zero volts output.

val has been shifted approximately95 degrees by adding a capacitor inthe other secondary winding ofT510, as shown in Fig. 7.

After the chrominance signal hasbeen demodulated, the resulting sig-nals are called color difference sig-nals.

Troubleshooting ChromaCircuit Problems

Color circuit problems will notonly cause weak or the lack of cer-tain colors, but also incorrect colors.

One of the most commonly usedmethods for the troubleshooting andisolation of color problems is theemployment of the color bar gener-ator and oscilloscope. The generatoris connected to the antenna termi-nals of the color TV receiver andadjusted to the color bar patternposition.

An ideal place to start checkingcircuit waveforms with the oscillo-scope is at the output of the band-pass amplifier which is approximat-ely the half -way point of the colorstages. The scope waveform ob-tained at this point should be es-sentially the same as the input signalof the color stages. The waveformsreceived as we check the color cir-cuits should be compared with theservice data for the particular chas-sis. If the waveforms lack amplitude,the defective component is likely tobe found in the bandpass amplifieror the associated control circuits.

Before attempting to pinpoint thedefective component in the bandpassamplifier circuit, first check the con-trol voltage inputs. If the color killeroutput signal is not correct, it cancause the bandpass amplifier to becut off. The ACC or blanker stagefeeding the bandpass amplifier canalso cause weak or complete lossof color.

22 I ELECTRONIC TECHNICIAN/DEALER, FEBRUARY 1975

-10 V---

# -I

ZeR0VOLTS

OUTPUT

ries are substituted in place ofInd C7 to illustrate the voltagerming a balanced demodulator

CHROMINANCESIGNAL INPUT

00000900

_L

0044009_4

C815 V

Fig. 6-Simplified schematic showing the in-

fluence of the chrominance signal on thecharge of capacitor C8 and C7.

Improper chroma circuit align-ment can also reduce gain and band-width. Incorrect operation of thetuned circuits can often be foundwhile making the chroma alignmentadjustments.

If the signal reaching the outputof the bandpass amplifier is at theproper amplitude, we will likely findthe defective component in the de-modulator stages or the color dif-ference amplifiers.

The output signal waveforms ofthe demodulators should be takenwith the scope and compared withthe ones in the service information.If the waveforms do not compare,the defective component will likelybe found in the demodulators andassociated circuits.

When we receive a color bar dis-play on the screen of the TV receiv-er and one of the primary colors isabsent, note the color and check theassociated color difference amplifierand the demodulator circuit. If allcolors are present but the color barsin the color bar pattern are out ofplace, check the AFPC circuits.

Locating the Defective ComponentColor demodulator circuit prob-

[AROMA SIGNAL

20 IN ID

70 pl

70

270 FA

20 IA

R Y SIGNAL0 DIFFFRENCI

R Y AMPBALANCE .>--66

2

B YBALANCE

2A

B Y SIGNALTO DIFFERENCE

AMPyo --FN

Fig. 7-Schematic diagram showing the chromademodulation circuit producing the R -Y and

B -Y color output signals. The G -Y output signalis developed by adding the -IR-Y) and --(134)signals in the color difference amplifiers.

LJ 7 9 10

1 2-3-4 S

Fig 8-The R -Y amplifier output display as

viewed with the oscilloscope.

Fig. 9-The 114 amplifier output display asviewed with the oscilloscope.lems are in most cases the result ofsome DC component failure: 1) Adiode can be shorted or open, andmay have excessive leakage. 2)Open coil. 3) Open resistor or achange of value. 4) Open trans-former, or poor solder connection atthe base terminals. In some cases,damaged while servicing the circuits.5) Open capacitor or with leakage.The phase shift circuits are seldomfound defective and only contain afew components.

A common method of locating thedefective component in the demodu-lator circuit is to remove the powerto the circuit and check the individ-ual components with an ohmmeter.Check the diodes, making sure theyare not open or shorted. Unsolderand lift one end of the diode andmeasure the front to back resistanc-es. If a diode is defective, replaceboth diodes with a matched, originaltype.

If electrolytic capacitors are usedin the circuit, and in many casesfound open, they can be bridged

with a capacitor of equivalent valueto restore the operation of the cir-cuit.

An oscilloscope can be used tocheck the coupling capacitance. Ap-proximately the same amount ofsignal should be present on eachside of the capacitor.

Chroma DemodulatorC'rcuit Alignment

There are several different typesof demodulator systems in use, andsome require a different set-up pro-cedure for the proper phasing ad-justment, but the oscilloscope wave-forms obtained at the grids of thecolor picture tube are the same ex-cept for the amplitude of the outputwaveform obtained.

(1) Connect the output leads ofthe color bar generator to the anten-na terminals of the color TV set.

(2) Set the function switch of thegenerator to the color bar patternposition.

(3) Adjust the controls of thecolor TV for the best possible pic-ture.

(4) Connect a wide -bandwidthoscilloscope to the output of theR -Y amplifier. The sweep frequencyof the oscilloscope should be set to15,750 Hz. We should now obtaina waveform display on the oscillo-scope screen similar to the oneshown in Fig. 8.

(5) Set the tint control of the TVset to the center of its range, thenadjust the course tint control ad-justment for zero amplitude on the6th bar of the oscilloscope display.

(6) Next, connect the oscillo-scope to the output of the B -Y am-plifier. Adjust the quadrature trans-former driving the B -Y demodulatoruntil the 3rd bar is at zero amplitudeas shown in Fig. 9.

The 6th bar is the blue color barand should be adjusted for zero am-plitude in the red demodulator cir-cuit. The 3rd bar is the red colorbar and should be adjusted for zeroamplitude in the blue demodulator.The blue signal will not pass throughthe red amplifier, and the red signalwill not pass through the blue am-plifier. The red or blue signal cannot pass through the green amplifier,because the G -Y amplifier is com-monly driven by the output of thered and blue demodulator.

FEBRUARY 1975, ELECTRONIC TECHNICIAN DEALER 23

DigitalFrequency

Counters forServicing -

Part 2By Joseph J. Carr, ET/D

Contributing Editor

Typical service -shop

applications

TRANSMITTER FREQUENCYMEASUREMENTS

Measurement of the output fre-quency of a two-way communica-tions transmitter is probably themost common "servicing" applica-tion of digital -readout frequencycounters.

The operating frequencies ofcommunications transmitters andthe tolerances beyond which thesefrequencies must not deviate arespecified by the Federal Communi-cations Commission (FCC). Exam-ples of the frequency ranges and re-quired frequency tolerances oftransmitting equipment typicallyserviced by independent electronicservice technicians are given in anaccompanying table. This tablelists the required and recommendedfrequency specs for transmitterscertified by the FCC for use in thetwo-way land and maritime com-munications categories. The fre-quencies of most transmitters inthese categories must be checkedand certified at least once a year bya technician with a First or SecondClass Radiotelephone license, andsome must be checked even morefrequently. In addition, the fre-quency of all transmitters must berechecked and certified by a li-censed technician whenever the cir-cuitry of the transmitter is repairedor serviced.

Frequency counters used to checkthe output frequency of transmitters

used in two-way land and maritimecommunications applications (andmost other categories of two-waycommunications) must be type -ap-proved by the FCC. (Exceptions tothis rule include frequency measur-ing equipment used to check ama-teur and class D Citizens Bandtransmitter frequencies.) To qualifyfor FCC type -approval, a frequencycounter must meet specific stabilityand time -base accuracy specifica-tions. A synopsis of the specs re-quired and/or recommended forfrequency counters which are usedto measure the output frequenciesof two-way land and maritime com-munications equipment is also givenin the accompanying table. (Anyfrequency counter which meets orexceeds the specs listed for the landmobile 25-50 MHz band also willbe more than adequate for servicingClass D Citizens Band equipment.)

The simplest method of checkingtransmitter output frequency with afrequency counter is illustrated inFig. 1. A short whip antenna is con-nected to input of the frequencycounter via a coaxial cable. Thetransmitter is then keyed on, and thetransmitted signal radiated by the

transmitter antenna is picked up bythe whip antenna of the frequencycounter. If the frequency counter isclose enough to the transmitter an-tenna (usually 500 feet or less, de-pending on the transmitter power),sufficient signal will be applied tothe input of the frequency counterto trigger it, and the output fre-quency of the transmitter will bemeasured and displayed by the fre-quency counter. Because the signalradiated by the transmitter's anten-na might interfere with normal com-munications on the same frequency,this method of frequency measure-ment is legal only for checkingClass D Citizens Band transmitters,and then only after it has been de-termined that the CB channel is freeof normal communications.

To prevent interference withnormal communications, FCC rulesrequire that frequency checks ofland, maritime and most other typesof two-way communication trans-mitters be performed with the trans-mitter output connected to a non -radiating load. One variation of thisspecified technique is illustrated inFig. 2. Here the transmitter outputis applied to a dummy load which is

24 j ELECTRONIC TECHNICIAN/DEALER, FEBRUARY 1975

thehe

1-A small whip antenna connected toinput of the frequency counter serves as"link" between transmitter antenna and

counter in applications in which this techniqueis permitted by the FCC.

TRANSCEIVER "TEE"COAXIAL

CONNECTOR

INLINE50 SIATTENUATOR

DUMMYLOAD

DIGITAL FREQ.COUNTER

Fig. 2-One method of measuring the outputfrequency of a transceiver connected to adummy (nonradiating) load. Value of the at-tenuator should be sufficient to reduce thetransmitter output signal to a level that cansafely be handled by the frequency counter.

THROUGHLINERE SAMPLER

Fig. 3-Another method of tapping off a por-tion of the output of a transceiver connectedto a dummy load. A few frequency countersare equipped with the "throughline" RF sam-pler illustrated here.

a shielded, noninductive resistorwith a power rating which exceedsthe maximum possible power thetransmitter is capable of delivering.A coaxial "tee" connector and 50 -ohm in -line attenuator feeds a por-tion of the output signal to the fre-quency counter. The attenuatormust reduce the signal to a levelthat can safely be handled by thefrequency counter. If insufficient at-tenuation is used, the frequencycounter will be damaged. (CAUTION:

Never feed the output of a transmit-ter directly into a frequency counter,and never connect the frequency

counter directly across a dummyload.)

Another legal method of measur-ing the frequency of a transmitter'soutput is shown in Fig. 3. Thismethod employs a coaxial "through -line" RF sampler between the trans-mitter output and the dummy load.The RF sampler picks off a smallportion of the output signal androutes it to the frequency counter.(Some frequency counters areequipped with an RF sampler.)

TEST EQUIPMENT CALIBRATIONDigital -readout frequency count-

ers can be used as accurate and con-venient calibrators of signal genera-tors during TV, radio and stereo re-ceiver alignment procedures or forperiodic calibration of signal genera-tors used only for servicing applica-tions not "governed" by FCC speci-fications. (Periodic calibration speci-fied by the FCC for test instrumentsused to check and certify the per-formance characteristics of two-waycommunications equipment shouldbe performed by metrology or man-ufacturers' labs equipped with FCC -approved standards.)

For example, a digital -readoutfrequency counter can be used dur-ing TV and FM receiver alignmentto accurately adjust and/or checkthe output frequencies of markergenerators and the subcarrier andpilot frequencies of stereo genera-tors. They can also be used to adjustand/or check signal generator out-put frequency during communica-tions receiver alignment. Some "lab-oratory grade" signal generators areequipped with a special high-level"counter" output intended specifi-cally for such applications. Thegenerator output (usually about100,000 microvolts) at this jack isapplied to input of the frequencycounter, and the "regular," attenu-able generator output is applied tothe receiver being aligned.

If your generator is not equippedwith a special high-level, constant -amplitude output, you still can useyour frequency counter to accurate-ly adjust and monitor the generatoroutput frequency by using the fol-lowing method: 1) connect the fre-quency counter to the attenuableoutput, 2) increase the generatoroutput to the minimum level re-

quired to trigger the frequencycounter, 3) adjust the generatoroutput to the desired frequency, asindicated by the frequency counter,4) disconnect the frequency counterfrom the generator output jack, 5)readjust the generator output to thelevel specified for the receiver, and6) reconnect the receiver to the gen-erator output. (Caution: The outputfrequency of some generators shiftsslightly when the output load ischanged. This is the reason that instep 6 the generator output shouldbe increased only to the minimumlevel required to trigger the frequen-cy counter.)

ADJUSTMENT OF TAPERECORDER/PLAYER

MOTOR SPEED

Many tape recorder/player man-ufacturers recommend that a digital -readout frequency counter be usedto set the speed of the motors intheir equipment. This procedure re-quires the use of a special test tapeon which is recorded a single -fre-quency audio tone.

The frequency counter input isconnected to the audio output ter-minals of the tape player, the tapeis inserted into the player and then,while the tape is playing, the motorregulator circuit is adjusted to pro-duce a frequency counter readoutidentical to the frequency of thetone on the tape.

I prefer a 1000 -Hz test tape forthis procedure because it permits meto read directly from the frequencycounter display the percent of motorspeed error, without the need forany mental arithmetic. A 1000 -Hztone will automatically "translate" aone -percent error of motor speedinto a frequency counter display of1010 Hz or 990 Hz (in other words,a shift of 10 Hz above or below1000 Hz for each one -percent errorin motor speed.) By using a 1000 -Hz test tape, motor speed errors assmall as .1 percent ("translated" bythe frequency counter to a shift of1 Hz above or below 1000 Hz) canbe detected with a reasonable de-gree of accuracy (resolution in fre-quency counter terminology).

A 100 -Hz test tape, on the otherhand, produces only a 1 -Hz shiftabove or below 100 Hz for a one -percent error in motor speed. Be -

FEBRUARY 1975, ELECTRONIC TECHNICIAN/DEALER j 25

cause most frequency counters arenot capable of measuring to closerthan 1 Hz, and because even thenthe reading is subject to the inherentdigital readout inaccuracy of ±-1count, the 100 -Hz test tape mightnot produce a sufficiently accurateindication of motor speed error.

STEREO FM RECEIVERADJUSTMENTS

In addition to the use of a fre-quency counter to verify the subcar-rier and pilot frequencies of stereogenerators, a frequency counter canalso be used to measure the frequen-cy of the 76- or 152-KHz voltage -controlled oscillator (VCO) signalin stereo decoder circuits equippedwith a phase -locked loop (PLL).

If the VCO is not on frequency,it is not locked to the 19-KHz pilot.Although such "lock -on" can beverified by applying the VCO andpilot signals to a scope and checkingfor a stable Lissajous pattern, it ismuch easier to measure the frequen-cy of the VCO signal with a fre-quency counter.

CHECKING AM RADIOCONVERTER FREQUENCY

Most technicians who service AMradios, particularly those who ser-vice car radios, have encountered alocal oscillator which is operatingbut is so far off frequency that thereceiver can not receive on any fre-quency. In such cases, DC voltagemeasurements are useless for diag-nosis because the converter tran-sistor (Fig. 4) is still operating nor-mally although the local oscillatorsignal is off frequency. Even thevoltage drop across the emitter re-sistor will change normally as theradio is tuned from one end of theband to the other.

The quickest and most positivemethod of confirming that the localoscillator is the cause of these symp-toms (or lack of symptoms) is toconnect a frequency counter to thecollector of the converter transistorand, with the receiver tuned to thehigh end of the band, measure thelocal oscillator frequency.

ELECTRONIC ORGANADJUSTMENTS

The "heart" of all electronic or-gans and synthesizers consists of

Q2

CONVERTER

Fig. 4-AM converter stage of a car radio. Ifoff -frequency converter causes "dead radio"trouble symptom, tune radio to high end ofband and use a frequency counter to measurethe converter frequency. If C1 or C2 is open,the frequency will be in the 2100.2200 KHzrange. If C3 is open, the frequency will be inthe 2500-3000 KHz range.

AMPLIFIER MIXER

0XTAL.OSC

LOW PASSFILTER

WW1=FREQ.

COUNTER

Fig. 5-Heterodyne method of extending themeasurement range of a frequency counter.

audio tone oscillators, which occa-sionally need adjustment. A digitalfrequency counter is the logical testinstrument for measuring the fre-quency of tone generators. How-ever, because the frequency of manyof the tone generators in an organmust be accurate to within a .01 or.001 Hz, you either must use a high-resolution frequency counter cap-able of resolutions to within .01 or.001 Hz or, if you do not have ahigh -resolution frequency counteryou must use a period counter andconvert the "time" readout to fre-quency by dividing the time intoone.

An alternative to both of theseapproaches is to buy, beg or borrowa frequency/period counter such asthe Hewlett-Packard Model 5 307Amodule of the Hewlett-Packard5300 series of "snap together" digi-tal counters. This instrument mea-sures the period (time) of a signaland then automatically converts thenumber of 10 -MHz time -base cycles(registered in a special calculatorcircuit during the period) into a di-rect readout of the frequency of themeasured signal. The 10 -MHz clock

SIGNALSOURCE

TRANSFEROSCILLATOR

RECEIVER OR OTHERZERO BEAT DETECTOR

Fig. 6-Transfer oscillator method of extend-ing the measurement range of a frequencycounter.

FREQ

COUNTER

mARREAWitRATOP

Fig. 7-Marker comparison method of extend-ing the measurement range of a frequencycounter.

rate produces a maximum resolutionwhich exceeds the .001 Hz requiredfor organ tone generator measure-ments.

EXTENDING THE FREQUENCYRANGE

If the frequency range of the digi-tal -readout frequency counter youown or can afford to buy does notpermit direct measurement of all thefrequencies you need to measure,you can effectively extend the fre-quency range by one of the follow-ing three methods:

HeterodyneThe heterodyne method of ex-

tending frequency counter range isillustrated in Fig. 5. The signal to bemeasured is mixed with a signalfrom an accurate, calibrated source.This mixing produces sum and dif-ference frequencies, which, in turn,are applied to a low-pass filter. Thefilter "blocks" the sum frequency,and only the difference (smaller)frequency is applied to and mea-sured by the frequency counter. Theresultant readout is then mentallyadded to the frequency of the cali-brated source. The total of thesetwo is the frequency of the signalbeing measured.


Frequency Specs For Land And Maritime Two -Way Communications Equipment

FrequencyBand AndCategoriesOf Stations

RequiredToleranceIn PPM

RequiredTolerance

In Hz

DesiredTolerance

;n PPM

DesiredTolerance

In Hz

FrequencyCounterLeast

SignificantResolution

' CounterError in

PPM

RequiredTime BaseTolerance

In PPM

RecommendedMaximumTime BaseCalibration

Cycle

RecommendedGate Time

Freq.MHz

Land Mobile 25.50 20 500 4 100 10 Hz .4 3.6 3 yrs. 7 mo. 10 Ms.

MHz 1000 200 .2 3.8

Land Mobile 150.8 5 750 1 150 10 Hz .066 .93 11 mo. 1 sec.

to 870 174 .057 .94174 MI -12

Land Mobile 470 to 5 2350 1 470 100 Hz .21 .79 6 mo. 100 Ms.

512MHz 2560 512 .19 .81

Base 25 to 50 20 500 4 100 10 Hz 3.6 3 yrs. 7 mo. 100 Ms.MHz 1000 200 .2 3.8

Base 150.8 5 750 I 10 Hz .066 .93 mo.15011 1 sec.

to 870 174 .057 .94470 MHz

Base 470 to 2.5 1175 0.5 235 10 Hz .021 .479 5 mo. 1 sec.

512MHz 1280 256 .019 .481

SSB Coast 1.6 to 12.5 20 3.1 4 1 Hz .62 2.5 2 yrs. 6 rno. 1 sec.

Stations 27.5MHz .72 .18 .036 .14 1 mo.

SSB Coast 156 to 5 780 1 156 10 Hz .064 .93 11 mo. I sec.

Stations 162MHz 810 167 .062 .93

Maritime 1.6 to 31.25 50 7.81 10 1 Hz .62 7.2 5 yrs. 1 sec.

Mobile 27.5MHz 1.8 .45 .036 .41 5 mo.

Maritime 156 to 10 1560 2 312 10 Hz .064 1.93 1 yr. 11 mo. 1 sec.

Mobile 162MHz 1620 374 .062 1.93 1 yr. 11 mo. 1 sec.

Courtesy of John Fluke Co

Transfer OscillatorIn the transfer oscillator method

of extending frequency range, illus-trated in Fig. 6, the signal beingmeasured is zero beated against alower frequency signal from thetransfer oscillator. A receiver (withan "S" meter) or a phase detectoris used as a beat indicator. The re-ceiver is tuned to the approximatefrequency of the signal to be mea-sured. The transfer oscillator then isadjusted until an audio tone isheard. As the zero beat audio tonedrops below your range of hearing,you use the "S" meter as a zero beatindicator. The "S" meter will ini-tially waver back and forth andthen, when true zero beat is at-tained, the meter needle will remainstationary. When this is accom-plished, you switch the transfer os-cillator output to the input of thefrequency counter and measure thefrequency.

Because you are measuring the"unknown" frequency by beating itagainst the transfer oscillator signal,which is a subharmonic of the "un-known" frequency, it is essentialthat you be able to determine towhich subharmonic of the "un-known" the transfer oscillator istuned. To avoid miscalculating the

subharmonic, use a transfer oscilla-tor frequency which is not less than1/20 of the estimated frequency ofthe "unknown" signal.

To calculate the frequency of the"unknown" signal, you merely mul-tiply the frequency counter readoutby the harmonic. For example, ifthe transfer oscillator is tuned to the5th harmonic of the "unknown" sig-nal, you multiply the frequencycounter readout by 5.

Marker ComparisonThe marker comparison method,

illustrated in Fig. 7, uses the beattone (audio) generated by hetero-dyning together the input signal anda standard marker frequency sup-plied by a precision crystal oscilla-tor. If, for example, you wish tomeasure the output of a 4500-KHzsignal source, you could beat a har-monic of a 100-KHz oscillatoragainst the signal, using a communi-cations receiver as the best indica-tor. Let us assume that the actualfrequency was 4500.9 KHz. Thiswill produce a beat note of 900Hertz in the receiver's output. Thecounter then is used to measure thefrequency of this beat note. Thecounter readout is added to or sub-tracted from the known 4500-KHz

marker to find the frequency of the"unknown" signal. In this case, thesignal is 900 Hertz above the mark-er, but the same beat note wouldhave been produced had the fre-quency been 4500 KHz - .9 KHz, or4499.1 KHz. The problem is to de-termine whether the signal is aboveor below the marker. By using acommunications receiver, we can"rock" the dial back and forth tosee the respective positions andthereby make the necessary deter-mination. When using a fixed -tunedreceiver, however, it might be neces-sary to use a marker frequency thatis one harmonic higher and then ob-serve whether the frequency of thebeat note went up or down.

CONCLUSION

The applications described in thisarticle are but a few of the manyfor which digital -readout frequencycounters can be used in the serviceshop.

Recent advances in digital -read-out frequency counter technologyhave made it possible to producelow-cost instruments that are bothversatile and accurate. Service tech-nicians not only can afford them,many cannot afford to be withoutthem.


New in Color TV for1975 -Part 6By Joseph Zauhar

Continuation of a series which analyzes

the new and significantly changed

circuits in 1975 color TV receivers. This

month we will review the new circuitsemployed in GTE Sylvania's

GT-Matic II chassis

GTE Sylvania's newcolor TV line features thesecond generation of self-adjusting TV receivers.The GT-Matic II colortuning system is employedin the GT-300 and GT-200 solid-state color TVchassis.

New integrated circuitsnow make possible the ad-dition of a new automaticcolor system and a auto-matic contrast and bright-ness system.

The new line also fea-tures a picture tube whichabsorbs room light to pro-vide higher contrast and asharper picture. In thesmall screen TV sets, anew in -line picture tube isused.

GT-MATIC II CIRCUITSMost of the GT-Matic

II's updating on previousGT-Matic systems takesplace on the Chromamodule, by the utilizationof integrated circuit IC-900, IC602, and IC600.The new automatic cir-cuits are employed in theE09/ 10/ 11 color TVchassis.

Automatic VideoControl System

The regular contrastand brightness controlfunctions have been re-placed with this new Au-

tomatic Video Controlsystem (Fig. 1). This cir-cuit package compensatesfor extremely wide varia-tions in station character-istics and program mate-rial, to keep the blackestand whitest parts of thepicture at the viewer's pre-set levels.

The video signal fromthe first video amplifier,Q210, drives the base ofan emitter follower delayline driver, 0900. Theoutput of the delay lineDL900, is AC coupled byC902 to the input (pin 8)of the video processing in-tegrated circuit IC900.

This AC coupling isnecessary, because allblack and white levels areto be re-established withinthe video processing ICby the black and whiteclamp blocks.

The black portions ofthe picture information issampled internally in IC -900 and clamped to afixed DC level. Thisclamping action providesa constant DC reference atthe picture tube, regard-less of variations in modu-lation at the transmitter.The contrast control,R917, provides a manualover -ride to permit adjust-ment for personal prefer-ence.

A white clamp circuit

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Fig. 1-The1-The Automatic Video Control system employs a "sample andhold" circuit made possible by using a new integrated circuit IC900.This circuit keeps the blackest and whitest part of the picture at thepreset levels. The circuit employs 100 percent DC coupling. Courtesyof GTE Sylvania.

detects the average bright-ness level of the video sig-nal and applies a correc-tion voltage to IC900 thevariable gain video stage(or video AGC) to main-tain a constant averagebrightness level at the pic-ture tube. The brightnesscontrol, R905, providesmanual adjustment to ac-commodate personal pref-erence.

The horizontal ratepulse at the emitter of theblanker, Q908, is integrat-ed by SC952, R953,C940, R954 and shapedso that its positive tip(Fig. 2) coincides with thehorizontal pulse backporch. This pulse is fed topin 7, of IC900. Conduc-tion within IC900 duringthe pulse interval chargesC902 at pin 8, keeping thehorizontal blanking DClevel constant. The com-posite video signal is nowclipped at the blankinglevel, preventing anynoise which extends aboveit from reaching the blackclamp circuit. This noiseprotection circuit preventsnoise impulses from estab-lishing an incorrect refer-ence level in the blackclamp circuit. This accom-plishment assures that theblack clamp responds onlyto the black portion of thepicture.

The color level circuitis based on the "Sampleand Hold" techniquewhich is made practicalthrough the use of IC's.This circuit examines thechrominance portion ofthe incoming signal to findthe highest peak chromalevel. It "remembers" thispeak and automaticallyadjusts the chroma gain ofthe receiver so that thepeak will be displayed ata predetermined level setby the user -preferencecontrol.

There are three areas ofperformance improvementover the previous GT-Matic system: (1) The"Sample and Hold" cir-cuit is a more sensitivepeak detector and is notadversely influenced by"typical" highly saturatedscenes. (2) More correc-tion loop gain. (3) It con-tains a noise inverter vir-tually immune to electricalnoise interference.

Color Killer andACC Circuits

The color killer control,R660 (Fig. 3), sets thethreshold level in IC602,which is related to a nocolor condition and holdsIC602, the second chromaamplifier off during themonochrome transmission.

The differential output


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clamp circuit. Courtesy of GTE Sylvania. Sylvania.

voltages from the ACCdetector in IC604 are fedto pins 1 and 16 in IC602.When a high level chromasignal is present, pin 16 ispositive with respect to pin1. A low level chroma sig-nal will produce a voltageon pin 16, which is nega-tive with respect to pin 1.The relationship of thesedifferential voltages is usedto vary the gain of the firstchroma amplifier in IC602to maintain a nearly con-stant chroma output at pin3, when the source, 3.58MHz chroma input signalat pin 1 of IC602 varies.

Preference level controlR632, is a part of a biasnetwork, consisting ofR626, R628 and R630,from +24 volts to ground.Its DC voltage is fed tothe level shifting circuit inthe color control, IC600,through pin 14. Here it iscombined with the enve-lope detected 3.58 MHzsignal being received. Theresultant signal is thensampled by the automaticcolor control systems'peak detector. The enve-lope related DC level isamplified by IC600, thecontrol voltage amplifier.This DC output signalcontrols the gain of Q600,the chroma control ampli-fier, and IC602, the sec-ond chroma amplifier. Re-

sistor R630 is a factory/service adjustment whichcompensates for internalvariables in IC600 and isadjusted for a no colorcondition when the colorcontrol is at minimum.

Automatic Color LevelControl Circuit

Amplified 3.58 MHzchroma information fromthe second chroma ampli-fier (Fig. 3) pin 14 ofIC602, is applied to pin 8of IC600. This signal isthen amplified at pin 9 bythe chroma amplifier ofIC600. The tuned 3.58MHz load, R640, C632and L635, feeds the signalthrough C608 to pin 2 ofIC600. This signal is thenenvelope detected andcombined with the DC con-trol voltage from the colorcontrol, R632, in a levelshifting circuit. Verticalblanking is also appliedthrough pin 12 to the levelshifter to remove any ver-tical interval signals(VITS or VIR) whichmay be present. The resul-tant information from thelevel shifting circuit is

then peak detected to pro-vide a control voltagewhich is dependent on thepeak amplitude of thechroma signal. The de-sired color level as deter-mined by the color control

setting, remains quite ac-curate. This control volt-age appears at pin 4 ofIC600 and is fed through0600, the chroma controlamplifier, to pin 6 of IC -602 to control the gain ofthe second chroma ampE-fier. The 3.58 MHz chro-ma signal level at pin 14 isdependent on the colorcontrol setting and thepeak amplitude of thechroma signal existingwithin the transmittedscene.

Chroma DemodulatorCircuits

The -(R -Y) and- (B -Y) signals are re-covered by a pair of syn-chronous detectors operat-ing on the R -Y and B -Yaxis contained in IC602.The G -Y signal is a prod-uct of R -Y and B -Y ma-trixing internally in the IC.

The 3.58 MHz CWfrom pin 2 of 10604 (Fig.4) is fed through a phaseshift network, L640 andC650, to pin 8 of thechroma amplifier and de-modulator integrator cir-cuit, IC602, providing theproper reference angle forthe R -Y demodulator. CoilL640 is adjustable toachieve the proper demod-ulation angles with the tintcontrol, R714, in the cen-ter of its range.

A second network, con-sisting of L658 and C654,shifts the phase angle ofthe R -Y reference signalat pin 8 of IC602 andfeeds the proper referenceangle for the B -Y demod-ulator to pin 7 of IC602.

Dark-Lite 50 ColorPicture Tube

The Sylvania Dark-Lite50 (Blackface) picturetube is a combination neg-ative guard band matrixscreen and dark filterglass.

The picture tube ab-sorbs room light in threeways: Once in the darkfilter glass as the light goesin towards the screen, asecond time by the BlackMatrix screen itself and athird time as it passesthrough the dark glassagain.

Light being emitted bythe phosphor screen passesthrough only one absorp-tion mechanism as itpasses through the darkfilter glass. This high ab-sorption of light gives thescreen its black appear-ance and the capability todisplay a much greaterrange of contrast anddeeper colors.

The 25 -inch color pic-ture tubes must be oper-ated at 30 kv to provideenough brightness reserve


and will be used only withthe 30 kv, E11 chassis.

COLOR TV CHASSIS Ell

The E11, color TVchassis which is used in25 -inch (diagonal mea-surement) color TV re-ceivers is the highest per-formance chassis, provid-ing 30 kv of second anodevoltage for the new"Blackface" color picturetube.

It employs a self-reg-ulating Ferro -Resonanttransformer, a new AFCand AGC circuitry for im-proved varactor tuner per-formance.

The E11-1 chassis usesa turret -type dual FETVHF tuner and a 70 -de-tent type UHF tuner. TheEl 1-2 features a 2 -buttonRemote Control alongwith a 20 -button Electron-ic Varactor tuning system.

The chassis employsseven plug-in IC's (eightin varactor tuner models)approximately 39 plug-intransistors (70 in varactortuner models) and a solid-state high voltage multi-plier.

IC circuits are used inthe Auto Color/AutoTint, Auto Black/White,Chroma Amp/SubcarrierRegenerator, Chroma De-modulator/Driver, Verti-cal Countdown, Horizon-tal/Sync, Sound Demodu-lator, and Voltage Regu-lator circuits (VaractorModels).

There are four plug-inmodules used in this chas-sis which are as follows:

(1) IF/Sound modulewhich is new and not in-terchangeable with otherexisting chassis or partsand contains improvedAFC and AGC circuits.

(2) Video / Chromamodule which contain thenew GT-Matic circuitry. Itis identical to and inter-changeable with the E09and El 0 Video/Chromapanel, but not interchange-able with older models or

panels.(3) Deflection panels

which are newly designedto drive the 30 kv deflec-tion system. It is not inter-changeable with other ex-isting panels or chassis.

(4) Bandswitch panelwhich is used only withvaractor tuner models.The panel is new and notinterchangeable with pre-vious E04 modules.

Power SupplyThe El 1 color TV

chassis differs from theE09/E10 by employing aconstant voltage trans-former (Fig. 5) to provideB+ regulation. This volt-age regulating transformerconsists of a core havingtwo magnetic loop paths,one is used for the pri-mary flux and the otherfor the secondary flux.

A regular power trans-former core has a commonflux path for both the pri-mary and secondary wind-ings which permits changesin secondary voltageswhen the primary voltagechanges because of linevoltage variations.

The transformer has alarge capacitor, C503,across the entire second-ary winding that maintainssecondary loop saturation.Because of the primary tosecondary magnetic loopisolations, the primary cur-rent does not go to ex-tremely high values tryingto support the saturationeffect, as the secondaryloop is kept in the satura-tion region by the largecapacitor.

Line voltage variationsfed to the primary windinghave little effect on thesecondary voltage levelsunder this condition.

The transformer sec-ondary taps provide theoutput voltages for thevarious B+ sources.

There are seven taps onthe secondary winding.One, three and five areused for the +135 volt

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Fig. 4-A new color processing integrated circuit, IC600, maintains thecolor level and aids in tint correction. Courtesy of GTE Sylvania.

Fig. 5-The Ell color TV chassis differs from the E09/E10 by employ-ing a constant voltage transformer to provide B-.- regulation. Courtesyof GTE Sylvania.

full wave supply. Tapstwo, three and four areused for the +36 volt fullwave supply. Tap three isthe common return or cen-ter tap.

COLOR TV CHASSISE09/ E10

The E09, El0 color TVchassis are electricallyidentical and use the sameset of circuit modules. TheE09 (Fig. 6) chassis is de-signed to be used in 19-inch models; the E 1 0chassis is used with 21-inch and 25 -inch TVmodels.

Both chassis provide ahigh voltage output of

26.5 kv for the picturetube.

The majority of the cir-cuits are placed on plug-in circuit boards and themajor components andsub -assemblies also plug-in for servicing conve-nience.

In the E09 and EIOchassis, the IF/Sound andDeflection modules areidentical to and inter-changeable with thoseused on the E05 and E03color TV chassis. A newVideo/Chroma panel con-tains the GT-Matic II cir-cuitry and is not inter-changeable with previousmodels.


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Fig 6-Shown in the photo is the E09 chassis which is designed to be used in 19 -inch (measured diagonally) color TV sets. The majority of thecircuits are placed on plug-in circuit boards. Courtesy of GTE Sylvania.

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Fig. 7-The E09/E10 color TV chassis features a full transformerpowered, electronic regulated power supply. Courtesy of GTE Sylvania.

Seven plug-in IC's con-tain the Auto Color/AutoTint, Auto Black/White,Chroma Amp/SubcarrierRegenerator, Chroma De-modulator/Driver, Verti-cal countdown, Horizon-tal/Sync and the SoundDemodulator circuits.

The chassis is laid outin a flat-bed design whichpermits free access fromboth sides of the chassisand circuit panels. Thecabinet bottom cover can

be easily removed for freeaccess to the chassis. TheTV chassis can be servicedeither by conventionaltechniques of analysis andreplacement of individualcomponents, or by replac-ing the entire plug-in cir-cuit module.

An Aperture Correc-tion circuit is employed inthe E09/E10/E 11 chassisto supplement the videopeaking. A three -positionvideo peaking switch per-

mits the set to be matchedto the reception environ-ment or the viewer's pref-erence. The range of thisswitch has been altered toprovide an improved com-promise between picturesharpness and backgroundnoise.

The chassis features afull transformer poweredelectronic regulated powersupply as shown in Fig. 7.

COLOR TV CHASSIS E08

The E08 color TVchassis is all solid stateand employed in portableTV sets where size, weightand carry -in service aremajor considerations.

This chassis is line con-nected and features single -panel construction em-ploying eight plug-in inte-grated circuits, 31 plug-in transistors and a solid-state high -voltage multi-plier.

The E08 chassis pro-vides 28 kv of secondanode voltage for the pic-ture tube, which is about4 kv higher than the pre-vious 19 -inch hybrid chas-sis and 6.5 more than theprevious 17 -inch hybridmodels.

Chroma-Line PictureTube System

The Chroma-Line pic-ture tube system used withthe E08 color TV chassisconsists of a 90 degree in -line picture tube and aprecision -wound dual to-roid deflection yoke. Thepicture tube is approxi-mately 13/4 inches shorterthan conventional deltagun designs. The linescreen is used with verti-cal phosphor strips insteadof dots, which improvescolor purity and makes itless susceptible to changewhen the TV set is moved.

A quadrapole conver-gency system is used withthe in -line picture tubesimplifying the conver-gence adjustments. Thereare only four dynamicconvergence adjustmentscompared to fourteen onDelta -gun systems. Thedynamic convergence isaccomplished by fourquadrapole windings onthe toroid deflection yoke.

Matrix and non -matrixversions of these tubeswill be used. The matrixtypes will be the new-Blackface" dark filterglass.


TECH BOOK DIGESTCondensed from a single chapter of a recently introduced TAB book,

by permission of TAB BOOKS, Blue Ridge Summit, Pa. 17214

Troubleshooting HorizontalDeflection & High

Voltage Circuits -Part 2

E. = ii

Fig. 10-Typical tube -equipped horizontaland high -voltage circuits.

TROUBLESHOOTINGHORIZONTAL AND

HIGH -VOLTAGE SECTIONS

The horizontal deflection andhigh -voltage section of the color setcan give the inexperienced techni-cian a very difficult problem when itcomes to troubleshooting. Besidesbeing driven hard in normal opera-tion, these circuits are complex, andit's sometimes difficult to understandthe operation from studying theschematic. In addition, these circuitsoperate within very close tolerances,which must be taken into account.The various feedback paths and in-terdependence of one circuit's oper-ation on the proper operationof an adjacent stage must beconsidered. Shock from high volt-ages in this section can be very pain-ful, if not fatal. Therefore, extracare must be exercised, not onlyfrom the standpoint of personal

safety, but equipment safety as well.For example, a momentary shortacross the high -voltage output of atube -type receiver will draw a heavyarc, but there is not much danger ofdamage to the equipment. This sameshort, although momentary, candestroy many transistors in a solid-state model.

Preliminary Checks

The first step in the isolation oftroubles in the horizontal deflectionand high -voltage section is to decidewhether the problem is in the deflec-tion system itself, or in the horizon-tal oscillator. If a raster is visible onthe CRT and the picture can besynced with the station signal, re-gardless of picture and raster quali-ty, there is usually little reason tosuspect the oscillator. When thevisual symptoms do not preclude thepossibility of oscillator problems,tests will have to be made before ac-curate conclusions can be drawn.

Some tube -type receivers use akeyed-AGC system, which is trig-gered by pulses from the horizontaloscillator. In these sets, the soundwill come on before the raster, dueto the slower heating of the deflec-tion tubes. If you can hear thesound and there's trouble with theraster, you can assume that the os-cillator is running, because the AGCis working and allowing the soundsection to function. However, theoscillator can still be off frequency.

The best test for determiningproper operation of the oscillator atthis time would be to observe thewaveform at the input of the hori-zontal output stage with a scope.This waveform is the sawtooth drivefor the output amplifier, and variesin exact shape with different modelsof receivers. Check the manufactur-er's service data for the correctshape. In tube -type models, as wellas in some solid-state sets, this saw -tooth will be slightly flattened on topunder normal conditions. This in-dicates grid (or base) clipping ofthe sawtooth. If tests reveal that theoscillator is the source of the deflec-

From Chapter 11, LOGICAL COLORTV TROUBLESHOOTING, by BenGaddis, TAB BOOKS, Copyright1974. A review of the complete bookfollows this article.


tion problem, refer to the earlierdiscussion concerning the horizontaloscillator.

Trouble SymptomsFaults in the deflection and high -

voltage circuits of Fig. 10 can affectthe shape and brightness of the ras-ter. Remember that some of thesesymptoms, especially those regard-ing brightness, can be caused byproblems in other sections of the re-ceiver. To insure that the deflectionand high -voltage circuits are not thecause of dim raster problems, makethe tests of the CRT electrode volt-ages as described earlier.

Principle symptoms of troublein the horizontal and high -voltagecircuits are those that affect theshape of the raster, the linearity ofthe horizontal scan, and the bright-ness of the raster. These visualsymptoms will be accompanied byincorrect voltages somewhere in thecircuits shown in Fig. 10.

A dim or missing raster can resultfrom a malfunction in the high -volt-age or focus supplies or in the gridor cathode circuit of the CRT.If the voltage measurements atthe CRT point to the deflectionsystem, measure both second -anodeand focus voltages. Also check forpresence of the boost voltage acrossthe boost capacitor. If the focus andboost voltages are present but thesecond -anode voltage is off, thetrouble is confined to the second -anode supply. If the focus is theonly missing voltage, check thecomponents in the focus circuit.When two or more of these voltagesare low, the problem must be in acircuit common to all, such as theboost or horizontal output circuit.

Failure of the second -anode sup-ply or its associated regulator willcause an incorrect high -voltage out-put. If the supply is only low, usual-ly the raster will be present, but pic-ture width and height will be affect-ed. If the size of the raster is affect-ed by the setting of the brightnesscontrol, look for trouble in the high -voltage supply or its regulator. Abad regulator can also cause fluc-tuations of raster width and focus,blooming of the picture, and fluctua-tions in brightness. In its early stagesof failure, the regulator might causea change in brightness when the

scene changes. Convergence willsometimes fluctuate also.

Voltage Checks

The best approach to any of thesetroubles is a check of the DC volt-ages in the high -voltage and regu-lator circuits. In tube -type receivers,substitute new high -voltage rectifierand regulator tubes to eliminatethese as possibilities. A check ofregulator current in shunt regulatorcircuits is also a good troubleshoot-ing aid. Some receivers include asmall resistor in the cathode circuitof the regulator tube so that this cur-rent can be easily measured by mea-suring the voltage drop across theresistor. Compare this current tothat specified in the service data.

Good focus not only depends onproper operation of the high -voltageand focus circuits, but also on theother voltages applied to the CRT.Only after a check of CRT voltagesleads you to the deflection systemare you ready to service this section.The best way to observe the focus-ing action is by means of the hori-zontal scanning lines. Many techni-cians mistake a smeared video con-dition, resulting from IF or videoproblems, as a focus problem. Whileadjusting the focus control, noticethe horizontal scanning lines. Thecontrol should be able to bring theselines into sharp focus.

There are three principle sourcesof poor focus: (1) the second -anodevoltage, (2) the focus voltage, and(3) the CRT. A voltage checkshould reveal either of the first twoproblems. If the high voltage is off,check out this problem first. In cor-recting the high -voltage problem,you will probably clear up the focustrouble as well.

Should the high voltage be at itscorrect yalue while the focusing volt-age is off, replace the focusing recti-fier. If this doesn't solve the prob-lem, check the other components inthe focus circuit. Capacitors that areleaky or that tend to change valuewith a change in temperature arecommon. Check the operation of thefocusing adjustment pot with aVTVM.

Damper DefectsThe damper and its associated

circuits are a common cause of high -

voltage problems. Remember thatthis circuit works in conjunctionwith the horizontal output, flybacktransformer, and yoke to producedeflection and the high -voltage pulsefor the high -voltage rectifiers.

Improper setup of the horizontaldeflection circuits is the cause ofmany failures in this section. Alwayscheck the high -voltage and efficiencyadjustments after making any re-placement in the horizontal deflec-tion section. In fact, it is good pro-cedure to check these adjustmentsroutinely on all bench jobs. Check-ing these adjustments early in thetroubleshooting procedure can savea lot of wasted time. A general ad-justment procedure is given in thefollowing paragraph, but always re-fer to the service data for the exactprocedure.

The purpose of these adjustmentsis to insure that the horizontal de-flection system and the high -voltagecircuits are adjusted for proper out-put and do not overload the horizon-tal output stage. Insert an ammeterin the cathode circuit of the outputtube. (Some models provide a de-tachable link for this purpose.) Ad-just the horizontal efficiency coil fora dip in the cathode current indi-cated by the meter. Refer to themanufacturer's info sheets for exactvalues. Set the brightness control tominimum to insure minimum CRTand maximum regulator currents.Set the high -voltage control to givethe proper second -anode voltage.Now check the cathode currentthrough the regulator-the cathoderesistor can be used for this purpose.Insure that the regulator currentshould decrease. If the regulatorcurrent is not within limits, checkthe components for proper value.After the above adjustments havebeen completed, recheck the outputcurrent and readjust it as necessary.Never operate the set for more thana very short period of time if thecathode current is high . . . the fly-back as well as the output stage maybe damaged

When working with problems inthe output and damper stages, keepin mind the sequence of operationdiscussed earlier. The damper causesdeflection from the left side of thescreen toward the center, while de-flection from the center to the right -

FEBRUARY 1975, ELECTRON'C TECHNICIAN/DEALER 33

T

Fig. 11-Device for testing high -voltage diodes. Fig. 12-Testing the VDR.

hand edge is accomplished with out-put stage current. Distortion at theleft of the screen can usually be at-tributed to the damper circuits,while distortion on the right side isusually caused by defects in the out-put stage.

Since the damper furnishes theDC supply for the output stage (andfor other stages in some sets), lossof the damper will naturally cause afailure of the stage. A shorted damp-er capacitor may cause a loss ofboost voltage. An open boost ca-pacitor will eliminate the high volt-age.

Transformer TroublesDefects in the yoke can cause ab-

normal output voltages as well as adistorted raster. In sets employingseries yokes (Fig. 10), an openyoke winding will cause a loss ofhorizontal deflection. A shorted yokewill cause a keystone -shaped rasteror other distortions. If parallel hori-zontal yoke coils are used, as insolid-state sets, an open in one yokecoil will cause a distorted raster anda short will decrease raster width.If there are many turns in the yokeshorted, the high voltage may becompletely missing.

A ringing yoke-one that tends tooscillate-will usually cause thehorizontal scanning lines to appearwavy near the left edge of thescreen. This problem can usually betraced to the capacitors in the yoke.Replacement of the capacitors willcure the problem.

Defects in the horizontal outputstage or flyback transformer willgenerally affect the entire deflectionsystem. If only a few turns areshorted in the flyback, the focus,high -voltage, and boost voltages willall be low. Usually, the width willalso be reduced. The greater thenumber of turns shorted, the greaterthe loss of high voltage. Don't over-look the possibility of shorts in sec-ondary windings such as the AGCtakeoff. These shorts can also resultin high -voltage defects. Most shorts

will cause heavy conduction in theoutput stage. Voltage checks andwaveform observation at the variousconnections to the output stage willusually pinpoint any problems inthis area.

Just as in other sections of the re-ceiver, a point is reached in thistroubleshooting procedure when in-dividual components must be tested.Due to the high power in the hori-zontal deflection system, standardtests cannot be used on some com-ponents. Tube testers may be finein some instances, but in this sec-tion the best tube tester is the setitself. Use either in -circuit voltagetests or tube substitution.

Solid-state rectifiers have replacedvacuum tube rectifiers in many sets.Due to their high -voltage character-istics, these diodes do not respondto conventional front -to -back resis-tance measurements that can be usedwith their low -voltage counterparts.The circuit in Fig. 11 may be usedto test high -voltage rectifiers forproper operation. After the rectifierhas been connected to the test cir-cuit, close switch Si. Only one ele-ment in the lamp should light, indi-cating DC. Should both elementslight, the diode is shorted. When therectifier is open, neither element willlight.

Voltage -dependent resistors at-tempt to keep the voltage acrossthem constant; therefore, a test suchas shown in Fig. 12 can be used asa quick check of VDR operation.As the DC input voltage is in-creased, the voltage across the VDRshould increase very slowly. If thevoltage increases linearly, the VDRis defective. A more accurate testcan be made by using the VDR'sspecified voltages as inputs and plot-ting the IR drop across the VDR.Comparing this chart with the speci-fication sheet will reveal any defects.

Some deflection circuits containanother type of variable resistorknown as a thermistor. The thermis-tor is a temperature sensitive resis-tor whose resistance usually de -

Fig. 13-Sawtooth test of inductors.

creases with a rise in temperature.This device may be tested by apply-ing the temperatures listed in thespecification sheet and comparingthe resistance across the thermistorwith the stated resistance. A quickcheck can be made by holding asoldering gun near the device andmeasuring the resistance. Be carefulnot to actually bring the solderinggun in contact with the thermistornor to overheat it.

Although a resistance check ofthe windings will readily reveal anopen in an inductor, seldom will thetest reveal the presence of a fewshorted turns. There are test instru-ments on the market that offer aneasy means of testing such com-ponents.

Sawtooth testing is a convenientway of making a quick check of in-ductors. Remove any resistance inparallel with the inductance andconnect the vertical input to thescope, as shown in Fig. 13. Jumperthe sawtooth output of the scope tothe vertical input. The horizontalsweep of the scope should be set tothe operating frequency of the in-ductor -60 Hz for power trans-formers, for example. Normally, aslowly damped train of oscillationswill be evident on the scope. If thereare turns shorted in the inductor, theoscillations are damped very rapid-ly, and only a few alternations arepresent. This test is fast, but re-quires a lot of experience in judgingthe scope presentation. Try this onvarious inductors at different fre-quencies to see how an inductorshould respond at various frequen-cies.

Keep in mind that one of the fast-est and most accurate means ofcomponent testing is componentsubstitution.

TECH BOOK REVIEW

Title: Logical Color TV Trouble-shooting (TAB BOOK No. 690)Author: Ben GaddisPrice: $8.95, hardbound; $5.95, soft-bound


Published: August 1974Size: 240 pages, 151 illustrations

This unusual new book combinesTV theory and repair know-how,and covers every aspect of TV cir-cuit troubleshooting from a practicalcommon-sense point of view. It isvery difficult to get so much infor-mation in one book . . . that's whyit's so rarely done and why this isprobably the first book on TV re-ceivers that is at once universal andunderstandable.

Starting with a systems approachto color TV, author Gaddis con-cisely explains the receiving andtransmitting subsystems and how theTV signal conveys information be-tween them. Then, it's on to a func-tional description of the color TVreceiver and a down-to-earth intro-duction to troubleshooting.

The author shows how to use thereceiver itself as a valuable test in-strument for TV troubleshooting.The screen becomes, in essence, an"oscilloscope" any servicer can useto interpret symptoms with unerringaccuracy. The text also explains theneed for such test instruments asdot -bar and sweep -marker genera-tors, vectorscopes and oscilloscopes,CRT testers, color TV analyzers,flyback and capacitor checkors, etc.

Once the trouble has been iso-lated to a stage, the next step is tofind out which parts to replace. Thisoften requires a thorough knowledgeof circuit theory. Accordingly, Mr.Gaddis has included an entire Chap-ter on tuners, one on IF amplifiers,another on the color section, andso on-in short, there is a wholechapter devoted to each section ofthe b -w or color receiver. Fromtube circuits to integrated circuits-nothing is overlooked. Just aboutany circuit one can name is ex-plained and illustrated for easy un-derstanding. Complete informationon resistance and voltage checks isalso included. CONTENTS: Troubleshooting - TestEquipment - TV Signal - RasterSymptoms - Color Receiver -Controls - Setup Procedure -Waveforms - Tuners - IF Stages- Alignment - TV Sound - Vid-eo Section - Sync and AGC -Deflection Systems - Convergence- Purity Adjustment - Verticalsection - Horizontal and High -

Voltage Sections - Color Section- Power Supplies - VoltageChecks - Resistance Checks.

NOW! Protect againstTransient Voltage Damageto TV, Stereo andHome Appliances with

Metal Oxide Varistors.TV Set manufacturers know that many component failures arecaused by voltage transients: lightning, voltage spikes and powersurges. Now you can do something about it . . . economically.

Insert easy to install GE-MOV metal oxide varistors in componentcircuits and prevent damage from transient voltage once and forall. The varistor absorbs the dangerous transient and dissipates itas heat. The cost is low. The installation fast and easy. It's likeoffering your customers an insurance package ... and it's anopportunity to make a profit!Our GE-MOV program is ready and waiting. For all the facts aboutthis addition to General Electric's growing replacement semi-conductor line, see your authorized distributor.

TUBE PRODUCTS DEPARTMENTGENERAL ELECTRIC COMPANYOWENSBORO, KENTUCKY 42301

GENERAL ELECTRIC


Ungar's RechargeableSoldering Station #194Cordless ... nickel cadmium battery powered ironallows the operator unrestricted freedom for hard -to -reach assembl es and breadboard prototypework. Perfect for radio, TV and other electronicequipment service and repair, in the field or at thebench. Ideal too for electronic kit assembly.

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TECHNICAL DIGEST

The material used in this section is selected frominformation supplied through the cooperation of therespective manufacturers or their agencies.

ADMIRALColor TV Replacement Modules

The chart lists the replacement modules for currentsolid-state modular TV chassis.

Note that there is no column for the M10 chassis. Thereare three replacement boards for the 3M10 and 4M10chassis; all other boards are wired into the chassis and areto be repaired, not replaced. The three boards availablefor replacement are:

M600M700/800M1000

Vertical A8952-2RGB/Horizontal A8951-2Pincushion A8954-3

* Starting at Run 13, the M25 chassis used a new IFmodule, A8919-2, and a 4.5 MHz amplifier, A8931-1. Ifyou need a replacement for Run 12 or earlier, useA8919-2 or -4 plus A8931-1 (Orders for A8919 -I will befilled with A8919-2 or -4 plus A8931-1).** IF modules A8919-2 & -4 include M200A, A8930-1,39.75 MHz trap. The -4 can sub for -2.# A8923-4 will replace -I or -3; A8923-3 will replace -1.Do not sub lower dash number for higher dash number.## A8926-1 and A8926-4 are interchangeable; either maybe replaced by the other.@ Substitute A8926-3. Do not sub -5 for -3.@@ A8923-4 was used in Run 10 through Run 12. A8926-5 was used in Run 13. The only difference in the twoboards is that resistors R145, R146 and R147 were in theCRT socket leads (at the plug) in Runs 10 through 12; inRun 13, they are placed on the board and become R745.R746 and R747.

Color TV Chassis G11/613/H10/H12/K15-Service Hint

If the Left Blue Horizontal control, R601, overheatsmake the following changes:

Replace the 2 w, Left Blue Horizontal control, with a3 w control, No. 75A64-39. Add a 30 (1, 5 w resistor, No.61A20-95, in series with either side of control R601 bycutting the foil and adding the resistor on the back side ofthe board. Make a good mechanical connection, then solder.This change was made in production as shown in the il-lustration. Also change coil T601 (on convergence board)if it has been overheated.

When ordering replacement parts for the convergenceboard components, check the service manual for the modelbeing serviced; components are not the same on all boards.

Color TV Chassis M25/M24-Service Hint

A condition of no vertical sweep and no sound can becaused by the following defective components.

In some cases, vertical output transistors are being re-placed unnecessarily. If you encounter the condition of novertical sweep on the mentioned chassis, check for absenceof sound. If the sound is also missing, check diode D105and resistor R116, 8.2 1-1, 3w. The B+ 25 volt voltagesource is scan -derived and diode D105 is mounted on thehigh voltage transformer.

Color TV Chassis K18-Service Hint

A 60 Hz hum bar in the picture can be caused by an openor poor solder joint at capacitor 0337 (100mfd, 30 volt,Part No. 67A200-101-5).

36... for more details circle 129 on Reader Service Card

ELECTRONIC TECHNICIAN/DEALER, FEBRUARY 1975

Color TV Chassis 611/613/H10/H12/105-Service Hint

If a symptom of insufficient vertical sweep, picture upfrom the bottom approximately four or five inches is noted,make the following changes:

Capacitor C606, 50mfd, 150 volts may have an open orpoor solder connection. Check the screws making theground connection between the foil on the board and thebracket. Capacitor C602, 50mfd, 10 volts can cause verti-cal jitter at the bottom of the picture as it opens. If thecapacitor is open, picture will be up at the bottom and red/green vertical lines will not converge. These parts arefound on the convergence board.

Color TV Chassis 4M10-Service Hints

If poor AFC performance is observed in this chassis, thediscriminator coil, L217, should be adjusted to enable theAFC to pull in to the correct tuning point. All availablechannels should be checked for performance after this ad-justment.

If a 920 KHz beat is observed on the low channels, theRF AGC Delay control, R319, should be checked for the0.1 volt rise setting.

In the event that either of the above conditions is notcorrected by the recommended action, the overall IFalignment should be checked and realignment performedwhere necessary.

MAGNAVOXColor TV Chassis T981/T982-Resistor R303 Location Change

The electrical location of resistor R303 has been changedin these chassis and it is recommended that all chassis with-out this change be modified as preventative maintenancewhen they are in the shop for service. Use the followingprocedure and accompanying illustrations to change theelectrical location of resistor R303.

1) Unplug the set and remove the cabinet back. 2)Remove the lead of resistor R303 from capacitor C300.3) Remove jumper B7 from the bottom master PC board.4) Remove the wire from point W11 and solder this wireinto one of the PC board holes left vacant by the removalof B7. 5) Install a piece of insulated wire from the othervacant B7 hole to the free lead of R303. Solder both endsof the wire. 6) Install a piece of insulated wire from W11to the junction of C300 and R300. Solder both ends of thewire.NOTES: A) Dress wires on top of master PC board andtoward the front of the instrument. B) Resistor is not usedon the T987 chassis.

Color TV Chassis T989 -6F Remote, 120 Hz Hum Bars

Some six -function, remote color TV chassis T989 ex-hibit 120 -Hz hum bars because of a ground loop. Thesebars are most noticeable on UHF channels. The problemis corrected by placing a jumper wire between the groundsat pin 5 and 15 on plug P/J2.

This plug is located among the three molex plugs be-hind the power supply filter capacitors. Plug P/J2 is thecenter plug, and pins 5 and 15 each serve as a ground forshielded wires.

Color TV Chassis T981/2/7-Loss of Flesh Tones

A defective capacitor, C154, can be the cause of loss offlesh tones in these chassis. Capacitor C154 is a 180-pf,polystyrene capacitor mounted on the signal board, be-tween the Chroma Demodulator module and the ChromaProcessor module. Since the capacitor is polystyrene, it issubject to degradation from excessive heat, flux, cleaningsolution, etc.

measure 100 pV lo 40 KY

...lor less mu $200!Now it's possible to get just about all the voltage measurement capabilityyou'll ever need. With these new instruments from Heath-The IM -2202Portable Digital Multimeter and the IM -5210 High Voltage Probe Meter-youcan have DC voltage measurement capability over a 166 dB dynamic range,for a total cost of only $197.900 for Loth instruments.

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Designed for field or bench, the portable IM -2202 will provide years of de-pendable measurement for the professional serviceman. Four rechargeablenickel -cadmium batteries (included) provide up to eight hours of continuousoperation. Or it may be operated from 110/220 VAC when continuous opera-tion is necessary. Full scale ranges are 100 mV (with 100 AV resolution!) to1000 volts DC, 100 mV to 750 volts AC, 100 AA to 1000 mA and 100 ohmsto 1000 kilohms. The 100% overrange allows measurement to 1.999 on allranges except 1000 VDC and 750 VAC, giving full 2 amp or 2 megohm capa-bility. All voltage ranges have high input impedance to prevent circuit loading.Internal standards allow calibration to 0.5% for DC and 1% for AC or, witha lab standard, 0.2% for DC and 0.5% for AC. Readout is a large, 31/2 -digitdisplay with automatic polarity indication and decimal point placement.Operation couldn't be simpler -a Range switch and four pushbutton Functionswitches select any of the measurement ranges. Easy operation, high accu-racy and dependable performance...you get them all with the HeathkitIM -2202. Available in kit -form only, $179.95".

New Heathkit probemeter measures TV tubevoltages to 40 kV...

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TV tube voltage measurements arefast and easy with the IM -5210 ProbeMeter. You just attach the ground clip to theTV chassis, place the probe tip against the tube'shigh voltage connector and switch on the meter. It's aneasy kit to build, taking about an hour to assemble. With a kit -formprice of $17.95*, it's just about the best high voltage measurement value onthe market. Also available assembled, only $24.95*.

Send for your free Heath catalogsThe latest Heath/Schlumberger Assembled Instruments Catalog

features a complete line of high performance, lowcost instruments for service and design applica-tions. Our '75 Heathkit Catalog describes theworld's largest selection of electronic kits - in-cluding a full line of lab and service Instruments.Send for your free copies today.

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AIL ORDER PRICES; r.o.s. FACTORY. 7E-315PRICES SPECIFICATIONS SUBJECT TO CHANCE WITHOUT NOTICE

... for more details cicle 109 on Reader Service Card

FEERUARY 1975, ELECTRONIC TECHNICIAN/DEALER 37

TESTINSTRUMENTREPORT

TELEQUIPMENT MODELD61 DUAL -TRACE SCOPE

Simplified controls which makewaveform measurements easier andquicker highlight the many featuresof Telequipment's Model D61 dual -trace, triggered -sweep, all -solid-state,10 -MHz oscilloscope.

The need for continuously variableexternal vertical gain controls andmanual gain calibration have beeneliminated in the D61 by use of 9 -posi-tion, detent-type "volts/division" con-trols which are internally precalibratedin each position. The 9 positions andthe 5-2-1 sequence in which the posi-tions are precalibrated provide verti-cal sensitivities over a range of .01volts p -p per division to 5 volts p -pper division of the 8 -centimeter -highscreen graticule. Because the gain fromone position to the next is never morethan 21/2 times, a continuously vari-able external gain control is not need-ed.

The concentric position traditional-ly occupied by the continuously vari-able vertical gain control on most oth-er scopes is occupied on the D61 bythe vertical positioning controls. (Ro-tating either of the vertical positioningcontrols completely counterclockwise

For more information about this testinstrument, circle 900 on the ReaderService Card.

until it clicks eliminates the respectivetrace.)

The design of the D61 also has sim-plified the selection and adjustment ofthe horizontal sweep rate. A detent-type "time/division" switch whichprovides 19 precalibrated sweep rang-es from .5 microsecond per division ofthe 10 -centimeter -wide screen grati-cule to 500 millisecond per divisionhas eliminated the need for a continu-ously variable external horizontalsweep control.

The concentric position usually oc-cupied by the continuously variablehorizontal sweep control on mostscopes is occupied on the D61 by thehorizontal positioning control, which,when pulled out, magnifies (increases)the sweep rate by a factor of 5.

The horizontal sweep ("time/division") control of the D61 also hastwo additional positions, labeled "extx" and "ch 2." In the "ext x" position,an external sweep signal from the"trig/ext x" jack on the front of thescope is applied to the horizontal am-plifier. In the "ch 2" position, the out-put of the channel 2 vertical amplifieris applied to the horizontal amplifier,making it possible to use both thechannel 1 and channel 2 vertical am-plifiers and their respective gain con-trols to establish equal horizontal (X)and vertical (Y) deflection sensitivitiesduring X -Y displays such as colorvector patterns. Because the X and Ydeflection sensitivities can be equal-ized, the resultant vector display pro-vides clearer and more meaningfulindications of vector pedal amplitudesand their relative phases. (The phasedifference between the channel 1 and2 vertical amplifiers is less than 1 de-gree at 50 KHz.)

The D61 operates in one of two dif-ferent modes of dual -trace operation,either "chopped" or "alternate." Themode is automatically selected by thesetting of the "time/division" control.When the "time/division" control isin any of the eight sweep positionsbetween "2ms/div" and "500ms/div"or is in the "ext x" position, the chan-nel -switching circuit operates as a free -running multivibrator and "chops" be-tween the outputs of the two verticalamplifiers at a rate of approximately100 KHz. When the "time/division"control is in any of the eleven positionsbetween ".5p,s/ div" and "lms/ div," thechannel switching circuit operates as abistable multivibrator and switchesthe vertical output amplifier from onevertical channel to the other at theend of each horizontal sweep. This iscalled the "alternate" mode.

The time base of the D61 can beoperated in either a triggered mode, inwhich no horizontal trace is producedon the screen unless a trigger signal is

applied to the trigger circuit, or thetime base can be operated in an"auto," or free -running, mode, inwhich a horizontal trace is producedon the screen even when no triggersignal is present. The "auto" mode isselected by pulling out the "trig level"control, which is located immediatelybelow the "time/division" control.(During "auto" operation, if triggerpulses above 10 Hz are applied to thetrigger circuit, the time base automati-cally reverts to the normal triggeredmode.)

A three -position switch immediatelybelow the "trig level" control selectsthe source of the trigger signal when-ever the "time/division" control is inany position other than "ext x" or "ch2." When the three -position switch isin the "ext" position, an external trig-ger signal can be applied to the triggercircuit via the "trig/ext x" jack. In the"ch 1" and "ch 2" positions of theswitch, the signal from the respectivevertical amplifier is applied to thetrigger circuit.

Either the negative or positive slopeof a signal can be used to trigger thetime base. The desired trigger polarityis selected by the "-I-/-" switch,located immediately to the right ofthe "trig/ext" jack.

The D61 is equipped with provi-sions for automatically triggering thetime base at either the TV horizontalline or field rate, depending on thesetting of the "time/division" control.When the "time/division" control is inany position other than "ext x" or "ch2" and the "ac/tv" switch is in the"tv" position, one half of the Schmitttrigger in the trigger circuit operatesas a sync separator which drives theother half, the time constant of whichis dependent on the setting of the"time/division" control. If the "time/division" control is any position be-tween "200.LS" and "500ms," the timeconstant is long, and the time base istriggered at the TV field rate. If the"time/division" control is in any posi-tion between "50ps" and ".5.is," thetime constant is reduced, and the timebase is triggered at the TV horizontalline rate. (When the "ac/tv" switchis in the "ac" position, the Schmitttrigger and other trigger circuits func-tion in the normal triggered mode.)

The "input" signals to the attenua-tors of the two vertical channels canbe either AC or DC coupled from the"input" jacks, depending on the posi-tion of the respective "ac/dc/gnd"switch. In the "gnd" position of theseswitches, the respective input circuitis opened and the vertical amplifierinput is grounded, providing a con-venient zero reference trace withoutthe need for disconnecting and


In times like these, it makeseven more sense to choose a Zenith.

For 6 good reasons.

These days, you'reprobably more determinedthan ever to make sureyou're getting yourmoney's worth.

That's why the thingsthat have made a Zenithcolor TV such a goodvalue are even moreimportant today.

1. Fewest repairs.A leading research organization askedindependent TV service technicians fromcoast to coast which color TV needed

fewest repairs. For thethird straight year,they named Zenith, bymore than 2 to 1 overthe next brand.

And whether youbuy a giant -screenconsole or compactportable, today'sZenith solid-stateChromacolor II bringsyou several importantfeatures designed togive you years of good,dependable service.

2.100% solid-state reliability.Built into every Chromacolor II set is arugged 100% solid-state chassis. Themost powerful chassis

Question: In general.of the brands you arefamiliar with, whichone would you sayrequires the fewestrepairs?Answers:Zenith 34%Brand A 15%Brand B 11%Brand C 7%Brand D 4%Brand E 3%Brand F 2%Brand G 2%Brand H 2%Brand I 1%Other Brands .. 3%About Equal . 16%Don't Know 9%

Note Answers total over 100%due to mullople responses

Lett The Cezann e. model SF2569PFIght The Deemer. model SF175OR S.m u fated TV =tura

Zenith has ever built, for a brighter,sharper picture. Modular solid-statedesign keeps it running cool so it lastslonger, makes service easier if it's needed.

And Zenith's patented Power Sentryvoltage -regulating systemprotects components againsthousehold voltage vari-ations you can't even see.

3. Saves energy.Many color sets, 3 ormore years old, use about as much poweras five 75 -watt light bulbs. Chromacolor IIactually uses less power than you'd needto light just two of the same bulbs.

The money you save won't pay foryour new Zenith. But it'll help.

4. Best picture.The heart of the Chromacolor II system isZenith's patented Chromacolor picturetube, with a level of brightness, contrast,and sharp detail that set a newstandard for the TV industry.Which may be one reason whyindependent TV servicetechnicians name Zenith, more

than any other brand, asthe color TV with thebest picture.5. Owner satisfaction.For a lot of people.though, the best reasonfor choosing a Zenithis also the simplest.

They already knowZenith quality because theyalready own a Zenith.

Fact is, in another recent nationwidesurvey, more Zenithcolor TV owners saidthey'd buy the samebrand again than didthe owners of anyother brand.

And that,we think,says more about theway we build thingsthan anything else.

6. We built it.We back it.

We're proud of ourrecord of building dependable, qualityproducts. But if it should ever happenthat a Zenith product doesn't live upto your expectations-or if you wantdetails of our surveys-write to theVice President, Consumer Affairs, ZenithRadio Corporation, 1900 North Austin

Avenue, Chicago, IL 60639.He'll see that your

request gets personal attention.And in times like these, that

means something, too.

Question: If youwere buying an-other color TV to-day,would you buythe same brandyou bought be-fore?

Answers:Zenith 82%Brand A 70%Brand D 69%Brand B 66%Brand E 63%Brand C 56%Brand 51%Brand J 49%Brand H 49%Brand G 47%Brand I 5%Other Brands 40%

Ar/Wrii SOLID STATE

C111111110hAkACOL01111The quality goes in before the name goes on.

. . . or more details circle 131 on Reader Service Card

For more information about this testService Card.

grounding the test probe.A 60 -Hz, 500 my p -p square wave

accurate to within 1 percent is avail-able at the "cal 0-5vpp" jack on thefront panel of the D61. This squarewave can be used to check the internalcalibration of the vertical channels orit can be used for triggering the sweepat the line frequency.

A negative -going rectangular pulseat a frequency determined by the time -base setting of the scope is available atthe "probe test" jack on the frontpanel. This pulse can be used to quick-ly check the frequency compensationof test probes used with the D61.

The display of the D61 can be in-tensity (Z-axis) modulated by apply-ing a 10 -volt or larger signal to theAC -coupled "Z -MOD" jack on theback panel of the instrument. A nega-tive -going signal blanks the display,and a positive -going signal intensifiesit.

inNtrutnent. cirelc 901 on the Reader

The Telequipment D61 scope isequipped with a 5 -inch CRT (standardP31 phosphor) and an 8 by 10 centi-meter graticule. The CRT acceleratinganode potential is 3.5 Kv. The scope is61/4 inches wide by 111/4 inches highby 16 inches deep and weighs 14.3 lbs.Price is $475.

DATA TECHNOLOGYHANDHELD DMM

If a combination of rugged portabil-ity, versatility and an easy -to -readdisplay are what you are looking forin a digital multimeter, Data Tech-nology's Model 21 palm -size, 31/2 -

digit multimeter might be the answer.This battery powered instrument is

capable of measuring DC voltages( I my to 1000v), AC voltages (1myRMS to 707v RMS) and resistances( I ohm to 2 megohms) plus capaci-tances ( 1 pf to 2 microfarad). Input

impedance in the DC measuring modeis 10 megohms, and 10 megohmsshunted by 40 pf in the AC measuringmode.

Although the Model 21 itself is only6.8 inches long by 3.25 inches wide by1.75 inches thick, its light -emittingdiode (LED) display is an easy -to -read.27 inches high.

The Model 21 is powered by fourrechargeable nickel -cadmium "AA"batteries. The external battery chargersupplied with the instrument fullycharges the batteries within 14 hours.(The charger DC output is pluggedinto a jack on the left side of the in-strument.)

A power -saver, push -to -read switchon the right side of the Model 21makes possible up to 2000 readingsbetween rechargings. Or, if you pre-fer, the push -to -read switch can belocked in the "on" position, for up to1 hour of continuous, hands-off mea-surements before recharging is neces-sary.

A choice of three battery chargersare available with the Model 21, forrecharging from either 115v, 100v or230v AC sources.

The four measurement functions ofthe instrument are selected by a single,four -position, rotary switch. The fourranges (2, 20, 200 and 2000) of theinstrument also are selected by a four -position rotary switch.

When the quantity being measuredexceeds the range selected, the over -range condition is indicated by con-tinuous flashing of the display. (In thecapacitance measuring function, anoverrange condition which exceeds thenext higher range is indicated byblanking of the three least significantdigits.)

Input to the Model 21 is via twoseparate pairs of miniature bananajacks on the bottom front of the in-strument. One pair is for AC and DCvoltage measurements, and the otherpair is for resistance and capacitancemeasurements. (The extra pair ofjacks between the two "regular" pairsis for an optional probe equipped witha separate push -to -read switch. Theoptional probe is available for $10.)

A tilt -up bail on the bottom of thecase serves as a convenient prop -upstand when the unit is not being hand-held.

The surface of the Model 21's im-pact -resistant polycarbonate case istextured to reduce the chance of slip-page when the unit is handheld.

Price of the Model 21, completewith battery charger and a carryingcase which can be clipped to your belt,is $269. An optional high -voltageprobe, for voltage measurements up to30Kv, is available for $15.


NEW PRODUCTSDescriptions and specifications of the products in-cluded in this department are provided by the man-ufacturers. For additional information, circle the cor-responding numbers on the Reader Service Card inthis issue.

THERMAL SPOT TESTER 700

Approaches the problem ofthermally caused intermittents

Wahl Clipper Corp. has added theThermal Spot Tester to their electronicproduct line. The tester approaches theproblem of thermally caused intermit -tents logically-no heating and then

artificially cooling the component withsprays. The tester directs heat to thesuspected capacitor or transistor, one

component at a time and heats themas in normal operation. The manufac-turer used its dryer background andbuilt a product to meet a specific need.The unit is small, lightweight, easy touse and carry. Retail price $21.95.

FUNCTION GENERATOR 701

Flexibility combined withexcellent generator capabilities

The Model 129 function generator,introduced by Exact Electronics Inc., of-fers more waveforms and versatility.A carrier generator produces sine,

square, triangle, positive pulse, nega-tive pulse, and positive sine waveformsfrom .1 Hz to 5 MHz, while an in-ternal AM/ FM generator producessquare, triangle and sine waveformsfrom 1 Hz to 1MHz for modulating

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TELEX NO. 65.1469 (OMER VAN

I IIti Manual

SolderABILITYTECHNIQUES

" NOTE: FANOVISION Manual will be sentFREE with purchase of $7.95 (or more) of

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the carrier generator. The carrier maybe manually, externally or internallygated or triggered. A pulse mode al-lows variable width and repetition rateto be set as desired, while a burstmode allows variable burst widths tobe set utilizing the burst width controlwithout affecting the carrier frequencyor repetition rate. FSK ( Frequency -Shift Keying) and PSK (Phase -ShiftKeying) extends the generator capa-bilities even further. FM width is vari-able from 0 to ± 500:1 about a centerfrequency utilizing either the square,triangle, or sine waveform of the AM/FM generator. AM modulation is ad-justable from 0% through 100% pro-viding double sideband suppressedcarrier capability. Simultaneous AM/FM allows independent control of am-plitude modulation and frequencymodulation simultaneously withoutany additional generators. Price is$795.

DIGITAL MULTIMETER 702

Features 41/2 digit readoutand 21 function -range operation

The Model 1450 41/2 Digit Multim-eller introduced by Data Precision Corp.is a full -function, bench -model mul-timeter featuring 1/2 -inch, seven-seg-

continued on next page

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MOTOROLA TRAINING INSTITUTE109 College Hill Road, Sommerdale, Pennsylvania 17093

B

a... for more details circle 107 on Reader Service Card . for more details circle 114 on Reader Service Card

FEBRUARY 1975. ELECTRONIC TECHNICIAN/DEALER 41

NEW PRODUCTS...continued from preceding page

These new IR devicesmake replacing Zenith

emiconductors aocal buy...

verywhere!

Now you can buy International Rectifier's "Guaran-teed" replacements for the most popular Zenith semi-conductors right at your local IR distributor. Besidescutting days from the usual ordering -shipping cycle,they're priced locally too - more than competitive withthe Zenith pricing structure.

Like everyone, we recognize Zenith's equipment istop quality, and we're not about to compromise theirname, or ours. We analyzed circuits and devices forfive months before we guaranteed that IR's deviceswill match,and meet or exceed Zenith's electrical andphysical parameters in all applications.

Right now you can pick up a kit' of 23 IR semicon-ductors, and save an additional 10%.

Add it all up: Local availability. Local price. Guar-anteed IR replacements for Zenith semiconductors.You can't lose.

13 -Transistors; 5 -ICs; 3 -Rectifiers; 1 -Diode; 1 -Crystal.

INTERNATIONAL RECTI FIERSemiconductor Division

233 Kansas Street. El Segundo. California 90245, Phone (213) 678-6281. for more details circle 111 on Reader Service Card

IOR

ment planar display, 100% overrang-

ing and 21 function -range operation.DC volts are measured from 100 mi-crovolts to 1000 v; AC volts from 100microvolts to 500 v RMS; resistancefrom 100 milliohms to 20 Megohms;and current, both AC and DC, from 1microamp to 2 amps. Frequency re-sponse for AC current and voltage isfrom 30 Hz to 50 KHz. Basic accuracyon DCV is ± 0.02 percent of reading± 0.01 percent full scale, ± 1 digit.Overload protection of ± 1000 volts isachieved electronically on all DC rang-es; 500 volts on all AC voltage ranges;and 115 v DC or AC on all resistanceranges. Current is protected to twoamperes with a rear -panel -mountedfuse. Common mode protection is 500v DC or peak AC with CMRR of 120dB at DC, greater than 100 dB at 50and 60 Hz. The meter measures 81/2inches wide by 31/2 inches high by 714inches deep without the handle assem-bly. Price is $325.

FUSE ADAPTER 703

Converts pigtail fusesto standard 3 AG fuses

A permanent replacement adapter,introduced by Workman Electronics, con-verts pigtail fuses to standard 3 AGfuses. The conversion is made by con-necting the spring ends to the leadwires, then simply insert the fuse endsinto the spring coils. The adapters areavailable in a package of 12, Model33-125 or display card of 12 packages.Model 33-125-12.


ELECTRONIC COUNTER 704

Features brightplanar readout

An electronic counter, Model 7026,is introduced by Simpson Electric. It hasa total display range of 1 to 1999999,a frequency range of 5 Hz to 50 MHz,and is guaranteed accurate to ± 1

Sim,,. /111 umens counnw

10000Dc.

1111111111WM

in at

le;lip-

count. The unit has been designed andengineered for line voltage operation.The compact, lightweight unit mea-sures 4 inches high by 81/2 incheswide, by 8 inches in depth and weighsapproximately 6.5 lb. It has an oper-ating temperature range of from --40°C to +70° C. A new .55 inch highbright planar readout can be read eas-ily from a distance of several feet. Thesample rate is continuously adjustablefrom five readings per second to hold.Hold input on optional rear panel con-nector provides sampling by eithercontact closure or external potenti-ometer with display storage being se-lectable by rear panel switch.

OVER -VOLTAGE PROTECTOR

Protects electronic equipment 705against damaging voltage transients

A solid-state device to protect homeentertainment equipment against po-tentially damaging voltage transients isa new profit -maker for electronic ser-vice dealers. It is being made availablethrough authorized entertainmentsemiconductor distributors by the Dis-tributor Sales Operation of GeneralElectric's Tube Products Department,Owensboro, Ky. Called GE-MOV,the device is a metal oxide varistor(voltage sensitive resistor) which re-sponds to voltage transients in 50 bil-lionths of a second, absorbs them, anddissipates them as heat. It is designa-ted GE -750. When wired -in to themain power circuit of a television, orstereo or tape player system, it willprotect against voltage spikes, linesurges and many lightning createdsurges. The device will not protectequipment against a direct lightninghit. Each device is individually pack-aged in a clear plastic bag with instal-lation instructions and a self-adhesivelabel to be affixed to the equipment.

TV and FM ANTI NNASAND ELECTRONLCS

ANTENNASFIELD -ENGINEERED

and TESTEDin your area

FOR YOUR AREACall or write: Box 865, Burlington, IA 52601

Phone: 319-753-1625


WAHL

DICK CHARGECORDLESS SOLDERING IRONWe couldn't make the best better.So we made it three times faster.Our original 'Iso-Tip' had all the features that peopleneed: complete portability; soldering heat in 5 seconds; upto 125 electronic joints or more per charge; battery oper-ated to eliminate AC leakage and the need for grounding;and "lock off" switch to prevent accidental heating. Com-plete with separate `drop in' recharging stand.

We use premium quality nickel cadmium batteriesthat recharge in 1/3 the time of the standard Wahliron - one to two hours for a partially dischargedunit, four and a half hours for completely dis-charged battery. It still gives tip perfo-manc upto 50 watts and over 700° temperature.So don't think of our new orange "Quick Cherge"cordless soldering iron as a fetter iron. It's alraadythe best. It's just three times faster.

WAHL CLIPPER CORPORATIONSterling, Illinois 61081.815-625-6525

"Manufacturing Excellence Since 1919"

... for more details circle 130 on leader Service CardFEBRUARY 1975 ELECTRONIC TECHNICIAN/DEALER j 43

DEALER SHOWCASEDescriptions and specifications of the products in-cluded in this department are provided by the man-ufacturers. For additional information, circle the cor-responding numbers on the Reader Service Card inthis issue.

AUTO STEREO CASSETTEPLAYER 706

In -dash player withFM/AM/FM multiplex

Panasonic has added a stereo cassetteplayer with built in AM/FM multi-plex to its car cassette line. The ModelCQ-840 is a compact cassette car en-tertainment center offering adjustablecontrol shafts that permit mounting in

almost any dashboard, a radio withAM antenna trimmer and FM dis-tant/local switch. Other features in-clude a stereo indicator light, fast for-ward control and tape ejector thatswitches radio on automatically. Priceis $149.95.

DOLBY FM COMPENSATOR 707

Provides direct listening pleasurefor Dolbyized FM broadcasts

Switchcraft, Inc., has introduced a 2 -channel compensator for enhanced di-rect listening pleasure for DolbyizedFM broadcasts. The Model 621 DolbyFM Compensator changes convention-al 75 microsecond FM de -emphasis

characteristic to the 25 microsecondcharacteristic used in Dolbyized FMbroadcasts. The unit should be usedby listeners now using Dolby circuitsin free-standing noise reduction re-ceivers or tape recorders so that theseDolby circuits can function properly.The compensator permits: 1) Listen-

ing to decoded Dolby FM broadcastswith a separate Dolby B -type noise re-duction unit. 2) Recording Dolby FMbroadcasts in B -type encoded form. 3)Listening/recording Dolby FM broad-casts with a separate Dolby B -typenoise reduction unit. Installation ofthe unit is simple: "record out" leadsfrom receiver, amplifier or tuner thatare connected to "line in" jacks or re-corder are disconnected. "Record out"leads are connected to the compensa-tor input jacks and compensator isthen connected to output leads of re-corder or noise reduction unit. Priceis $12.95.

TELEPHONE AMPLIFIER/MONITOR 708

Automatically records incomingand outgoing conversations

Workman Electronics Products, Inc., in-troduced a battery -operated telephonedevice called "TELE-SECRETARY"which can be used with any standardportable tape recorder. The telephoneamplifier and monitor has three leadsextending out, the wire with two alli-gator clips is connected directly to thetelephone or telephone line. The sec-ond wire with a small phone plug isthe "Remote" wire. The third wire

A FEW TYPICAL VALUES FROM OUR NEW CATALOGJAM PACKED WITH SURPLUS ELECTRONICS BARGAINS -

NICKEL CADMIUM BATTERIES

rout

lab1500 1502

Here ,s a new FICA Nu. 1446400.1,5.0 V - 1200 rnA1010 hour rale 120 mA.I Four sealed cells that arearranged in Iwo rows of two each. sire, 15/16- die1.5/0". Iwo cells have a metal tab for connection.Perfect for various 5 volt IC applications. Thecharging rate is 120 mA for 14 to 16 hrs. and thetrickle rate is 12 mA. Ste overall is 15/16" H .1 13/16' W x 3-1/4" L. It coines complete with

rum, Shoat w I 2 lbs. each.1500 $6.75Another excellent nickeleadmrum battery. this OMwith ten sealed cells arranged in a plastic sleeve case.they are about half C sire. GouldNo. 402676, 12 V750 mA. 1010 hour rate 75 mA.I Each end hasmetal tabs for connection. The charging rate is 75 mAfor 14 Ia 16 hours, and the trickle rate is 7.5 mA. Itio 9n. with instructions. The sire of the case d 1" dia.

x .4 L. Shpg. W1. - d lbs each.1501 $11.00

Series connected, two rows of four cells each, 1.75V1/3 AA site. 130 mA 14.10 hour 13 rnA./ TheserriIs have lab connections and plastic jackets. Size

ar', row is 9/16" dia. x 2-5/8" L. Sh. I b.1502 14.75

This 113 -cell battery has three banks of six each.Excellent for mobile applications as well 55 others.24 volt. as ampere hour. Sire 914" z 114" . 1Y.".Wand new. Shpg. wt. 2 lbs.1503. $11.00

This is a single cell with a capacity of 0.6 ampere hourarid a sire of 11/16" e 1-3/4". Shpg. wt. '.alb.1504. 51.00

HERE ARE A FEW TRANSFORMERS -We have the country's LARGEST SeleCtiorof surplus stock transformers. literally hun-

03 dreds. Here are two of our most popular

We have an enormous range of sr ientif lc andelectronic items for all kinds of variouscations. Besides transformers and batteries, wehave a multitude of other highly useful items.semi -conductors, switches, motors, connectors,integrated circuits, optical items, relays, timers,power supplies, and many others. Write for ourFREE CATALOG TODAY, and rhe k ourunbelievable low -low prices

Mere is one of our most popular transformers. It is

ideal for logic/op-amp supplies. as the two 19 voltwindings can be used to provide inputs to two 15volt regulators Do provide =t5 volts) and the 8.7volt winding can be used to provide input for e 5volt regulator for a .5 volt TTL supply. Also excel.lent for an audio amplifier supply by putting wind-ings in series. Brand new, WI. 4151b. lead length 24".Cot No 1060 11.75

ANA,

A highly desirable transformer for large audioamplifiers. the 70 volt winding can be used at6 amperes if the other windings are used 101 zeroor light loads. Sire 35" x 414" x 414". lead length2 1T. weight 9/. lbs. Brand new.Cot No 1063 113.75

CATALOG. 0* redoes sad sr wile

POMMES WELCOME.New Of MI, 017 631 OTT Il SMOOT0WwwwWinil - IIMMEnEmmo 5101/0 *mow C OD1014.

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WRITE FORFULL DETAILS

Choice of: 3011, 48" or 60"models (size indicates spread of lower bracket).

SOUTH RIVER METAL PRODUCTS CO., INC.SOUTH RIVER, NEW JERSEY 08882

... for more details circle 103 on Reader Service Card44 ' ELECTRONIC TECHNICIAN/DEALER, FEBRUARY 1975


with the larger phone plug is used asthe "audio" wire. By connecting thedevice to both the telephone and thetape recorder, it will automatically re-cord all incoming and outgoing con-

versations. The main purpose of theunit is to start and stop the tape re-corder whenever your telephone is be-ing used, even while you are out. Theunit can be used on any extension.

IN-STORE SIGN

Constructed ofbrushed aluminum

fers the convenience of a 4 -digit tapecounter, non -magnetizing record head,

mic and auxiliary inputs, and calibra-ted VU meters. Price is $499.95.

SMOKE ALARMS

The alarm is triggered ifits battery is about to be expended

Two smoke alarms, one powered by709 a battery and the other by electricity,

have been added to the family of se-curity products offered by Mallory Dis-

Altec Corp., Sound Products Div., hasprepared an in-store dealer sign withthe words: "Altec . . . The Sound ofExperience." The sign is made ofbrushed aluminum with the Altecname etched out and appearing inblack. The sign measures 24 inches

wide by 12 inches high and is part ofa new promotional campaign that in-cludes speaker cutaways, consumer lit-erature and booklets and other point -of -purchase material to reinforce the"experience" theme.

TAPE SYSTEM 710

Completely self-contained,open reel stereo system

A completely self-contained, open -reel tape recording system is intro-duced by Sony. Designated the ModelTC-570, the new recorder featuresSound -On -Sound and echo recordingcapability. The tape system includesbuilt-in power amplifiers and two full -range, lid -integrated stereo speakers.Among the features developed for thesystem are three -head recording/play-back for full monitoring capabilities,straight-line record -level controls, rec-ord equalization selector switch, andleft and right tape/source monitor se-lector switch. The three -speed unit of-

711

tributor Products CO., a division of P. R.Mallory & Co., Inc. The smoke alarmsare designed for use in homes, apart-ments and businesses and can be easilyinstalled. Each alarm is about six andone-half inches in diameter and threeinches thick. The battery -poweredsmoke alarm, the Model SDA-3, ispowered by a 12.6 -volt DURACELLmercury -cadmium battery (304116).A feature of the battery is that it is en-gineered to trigger the smoke alarmif its power is about to be expended,

continued on next page

IT'S NO PUZZLETO ORDER

OELRICH SERVICE FORMSFOR TV -RADIO i& 2 WAY RADIO SERVICE LEGAL FORMS FOR CALIF. FLA.UTAH NOW Al YOUR PARTS JOBBER OR WRITE FOR CATALOG A64

OELRICH PUBLICATIONS4040 N NAS-IVILLE AVE CHICAGO ILLINOIS 6063

. . for more details circle 117 on Reader Service Card

INFopi,A

00 r .1-741),

&la "°ti

CIFIN 13°5 S84" 0" SINGSivee Kits do it all! Your kits elimirate nerd for stocking largereplacement inventory. This is all yo.i need to make easy repairson ... 8 tracks, cassettes (both imports aid domestic) whetherdrive belt is round, flat or square. Kit; COME complete with amplerubber stock, Instant -Weld Adhesive, jig for controlling cuts, razorblace and special cleaning compound.

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1:1 Send literature wi-h details and name of nearest Distributor.

rareC)mpany

AddressCity State Zip

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ONEIDA ELECTRONIC MFG., INC.P.O. BOX 678 NORTH COTTA3E STREET

MEADVILLE, PP. 1635PI -ONE 814/336.2125

. . . tor more details circle 116 an Reader Service Card


40 KVDUALRANGE

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Send literature and nameof my distributor.Polaris New York2862 FULTON STREETBROOKLYN, N.Y. 11207

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J... for more details circle 127 on Reader Service Card

IEC-MULLARD

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46 1 ELECTRONIC TECHNICIAN/DEALER, FEBRUARY 1975

DEALER SHOWCASE...continued front preceding page

thus calling attention to the need fora replacement battery. The ModelSDA-2 smoke alarm operates fromstandard electrical current. The device

has a built-in pilot light to indicate itis functioning. The Model SDA-2 ispriced at $61.60 and the Model SDA-3 is $81.

CASSETTE RECORDER 712

Ideal for educational andvisual aid consultants

A full -feature cassettecorder, engineered to meetmendations of educationalaid consultants, has been

player/re-the recom-and visualintroduced

by Channel Master. It incorporates anumber of design features to benefitboth student and teacher. The record-er, Model 6323, has a digital counterwith reset button that permits the stu-dent to log specified points within ataped lecture and locate them instantlyfor playback. A pushbutton pause con-trol permits a student to proceed at hisown pace. The unit has a built-in con-

denser microphone and a full comple-ment of input and output jacks for re-mote control microphone, private ear-phone. and auxiliary input. An auto-

matic shutoff protects the unit againstexcessive wear. The recorder functionson either house current or four "C"batteries. Price is $74.95.

REMOTE CONTROL SPEAKERTIMER 713

Includes a60 minute timer

A new Remote Control SpeakerTimer, Model No. N70-162 fromWorkman Electronic Products, Inc., allowsyou to listen in private or through aremote speaker. It will turn a TV seton or off from a distance of 15 feet.

The system contains a 60 -minute tim-er, volume control, TV remote selectorswitch, 21/2 inch full fidelity speakerand 15 feet of five conductor cablewith AC cord. Also included is an ear-phone jack which allows you to plugin an earphone or pillow speaker forprivate listening. IN

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STREAMLINED AND CONVENIENTAll the information for a given mod-el is contained on two facingsheets. The special bound -leaf for-mat allows pages to lie flat whenopen. Each volume is organized al-phabetically by manufacturer, thennumerically by model number. Inaddition, a handy Chassis/ModelFinder is bound into each volume.Regular list price for each year'scoverage - 2 BIG volumes - is$19.90. All 8 volumes normally sellfor $79.60. Your price is ONLY$35.95... a savings of nearly $45.00!

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Name

Company

Address

Phone

Tech/Matics Schematic offer

City State Zip(Paid orders shipped prepaid. Da. resident add 6% Sales Tax. Outside USA 10% extra.)

ET -25

... for more details circle 125 on Reader Service CardJ


r

CLASSIFIEDRATES: 35c per word: 450 per word Bold FaceType. Add $3.00 if you wish Box Number. Minimum$10.00 charge. Classified Display Rate billed$40.00 per inch, 1 inch minimum. Remittance mustaccompany order. Mail ad copy to: Roz Markhouse,ET/D, 757 3rd Ave., N.Y., N.Y. 10017.

For Sale

BUILD A 'SPACE-AGE- TV CAMERA!!Only Dinh soltd- ttttt camera available in kit formor factory assembled. Ideal ID experimenters.industry, education. etc. Completely sell.Contained Connects to any TV set without

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RECONDITIONED Test Equipment.$.50 for catalog. Walter, 2697 Nickel,San Pablo, CA 94806.

For Sale

RCA -Solid -State Oscilloscope, type WO -505A $175.00RCA -Master Chro-Bar Generator, type WR-515A 100.00RCA -Solid -State Master Voltomist, type WV -510A 90.00RCA -Bias supply, type WG-307B 10.00RCA -Marker Signalyst, type WR-525A 20.00RCA -25 inch. CTC-24 color television, with brand-new Matrix

Picture Tube and flyback transformer, table model (no stand)Jud Williams -Transistor Curve Tracer, Model AEico-Solid-State Signal Tracer, Model 150Conar-Resistor-Capacitor Tester, Model 311Conar-Communication Transmitter -Kit, assembled ....Conar-Color Television Chassis, Model 600 with Cabinet,

less Picture Tube 25.00Sencore-Transistor FET Tester, Model TF17A 20.00Electro-Transistor-Power Supply, Model -E3 0-24 @ 100 ma. 10.00Kine-Color Circuit Analyzer, Model CA378 10.00

Contact: William D. Shevtchuk1 Lois Avenue, Clifton, N.J. 07014. Phone: 201-471-3798

send a message......write here.

1. Number of insertions: (circle) 1 2 3 6 122. Start with (month) issue (Copy must be in by 1st of month preceding)3. Amount enclosed: $PAYMENT MUST ACCOMPANY ORDER WE'LL BILL RATED FIRMS NO AGENCY COMMISSION

NAME COMPANY

STREET

CITY STATE ZIPMAIL COPY FOR AD(S) TO: ROZ MARKHOUSE. Electronic Technician/Dealer, 757 Thin., Ave New York. N.Y. 10017

LRATES: 35¢ per word; 45v per word Bold Face Type. Add $3.00 if you wish Box Number.

Minimum $10.00 charge. Classified Display Rate billed $40.00 per inch, 1 inchminimum.

ELECTRONICTECHNICIAN/DEALER CLASSIFIED

BURGLAR alarm police dialing unit$29.95. Automatic emergency tele-phone equipment. Free literature. S &S SUPPLY, Box 12375E, North Kan-sas City, MO 64116.

Antique radio tubes and Riders Man-uals for sale. Less than dealers' prices.G. C. Goodwin, 126 W. First Ave.,Rankin, IL 60960.

LOW noise resistors -%W, 5%, car-bon film from 10-3.3 Meg for 31/20each. Fifty of one value for $1.25. 10%discount over $50.00. 750 postage/han-dling. Free samples and specifications.COMPONENTS CENTER E, Box 134,New York, NY 10038.

LIQUID crystal. 3% digit wristwatchdisplay. New, with instructions forbuilding wristwatch. Final close-out.Less than original, factory wholesaleprice. $5.50 each. Two for $10.00. TRI-COUNTY WINSLOW, INC., Box 5885,Grand Central Station, New York, NY10017.

For Sale: 72 sets of Sam's PhotofactSchematics, 1218-1289. Make Offer.Contact: Mr. Wayne A. Frye, Route2, Box 173, Edinburg, VA 22824.

We have for sale, copies of old Radio& TV diagrams (Atwater Kent, Cros-ley, Philco, ATC). Complete Rider

180.00 Perpetual Troubleshooter Manual.90.00 Charges are 250 per sheet, minimum35.00 order $2.00. Send stamped self -ad -15.00 dressed envelope. We also have for15.00 sale original old tubes and parts.

Hartsville Television & Cable Ser-vice, R.D. 1, Hornell, N.Y. 14843.

DYNACO-A-R, transistors, repairs -boards & units, speaker service. Sendfor prices and details: BEAR ELEC-TRONICS, 177-ET-Hillcrest Road, Mt.Vernon, NY 10552.

Japanese Transistors, Kit $23.44 -contains 24 most widely used transis-tors, including 14 power transistors.Over 500 types available. Free catalog.West Pacific Electronics. Box 25837,W. Los Angeles, CA 90025.

Complete Construction Plans -TELE-PHONE: Answering Device, Auto-matic Dialer, "Black Boxes," Call Di-verter, Call Limiter, ConferenceBridge, Central Dial Exchange, Melo-dic Ringing, Recorder -Actuator, Re-mote Control, Schematics, Speaker-phone, Telelink Burglar Alarm, VoiceScrambler, $3.00 each. ELECTRONIC:Biofeedback Conditioner, HorticultureStimulator, Multifrequency EncoderNetwork (Speeds telephone calling100%!). $5.00 each. ONE YEAR SUB-SCRIPTION: Telephone -ElectronicsNewsline $3.00. Super -illustrated, 16 -page catalog of plans, many more, 50cents. All of the construction plansabove, $14.95. TELETRONICS COM-PANY OF AMERICA, P.O. Box 3486,Hollywood, CA 90028. USA.


T.V. shop close-out sale: CommonTubes 70% off list price. 20% off listprice of Heath Kit Vectorscope, Mark-er/sweep generator, B & K CRT Test-er, Channel Master Field StrengthMeter & other misc. items. Postagepaid. For more information write:Ainsworth Communications, P. 0. Box23, Ainsworth, Nebr. 69210, or phone1-402-387-1990.

MANUALS - instruction books forGov't surplus receivers, transmitters,test sets, scopes, radar. Thousands instock. Send 500 (coin) for large list.Books, 7218 Roanne Drive, Washing-ton, DC 20021.

OLD RADIO SHOWS on cassettes.$1.50 per show. Free catalog. RadioClassics, Box 804, Mattituck, NY11952.

USE YOUR SCOPE (ANY MODEL,NO REWIRING) TO TEST TRAN-SISTOR IN/OUT CIRCUIT. SIM-PLE INSTRUCTIONS $1.00. SCHEKTECHNICAL SERVICES, 8101SCHRIDER ST., SILVER SPRING,MARYLAND 20910. 10-73-12

PRACTICAL applications of digitalIC's. 100's of tips, circuits, projects onTTL. 443 pp. $19.95, money -back guar-antee. GEA, P.O. Box 285, Northfield,OH 44067.

VOICE descramblers, several modelsto operate with any scanner or moni-tor receiver, tone signaling encodersand decoders, other items and kits.Send 25 cents for new catalog. KRYS-TAL KITS, Box 445, Bentonville, AR72712.

VISTA DIGITAL CROSSHATCH

For professional, accurate color T.V.convergence. Digital IC's coupled witha crystal timebase oscillator provideSYNC for precise horizontal and ver-tical lines.Accurate 8 x 7 crosshatch or 56 dotpattern. A.C. power 2 x 3% x 6 in.Fits in tool kit. Completely assembledin U.S.A. $41.95. Ready to use. Include$2.00 for shipping and handling.

PHOTOLUME CORPORATION118 EAST 28 STREET, NEW YORK, NY 10016

Television Service Business for Sale.In operation for nearly 25 years andwe have more work than we can han-dle. We have several contract accountswhich keep us very busy, plus a largefollowing of regular customers. Callor write for particulars: Mr. Harry R.Johnson, VALLEY TV & APPLI-ANCE CENTER, 1252 North MainSt., Salinas, CA 93901. (408) 449-7208.

ELECTRONICS book discounts. Save!Free selected, reviewed list. T/ DOC,Box 340, Centerville, VA 22020.

BUSINESS FOR SALE: Well equippedTV shop with good business, virtuallyNO COMPETITION, in two -countyarea, South -Central Georgia. Lucra-tive, unlimited potential. Admiraldealership and Mastercare ServiceCenter available. Magnavox servicealso available, possibility of Zenithservice contract. Owner has two shops,cannot devote sufficient time to both.Selling most lucrative shop in order tohave more time in home area. For fulldetails, write or call (not collect)Mickey's TV Sales & Service, 103First St. South (Next to Sears), P.O.Box 476, Soperton, GA 30457. Phone(912) 529-4440.

HEAR POLICE/FIRE Dispatchers!Catalog shows exclusive official direc-tories of "confidential" channels. Sendself-addressed stamped envelope. Deal-ers wanted. Communications, Box 56 -ET, Commack, NY 11725.

ELECTRONIC ORGAN KITS, KEY-BOARDS for organs and synthesizers.Independent and divider organ tonegenerators, diode keying. 350 for cata-log. DEVTRONIX ORGAN PROD-UCTS, Dept. A, 5872 Amapola Drive,San Jose, CA 95129.

BUILD your own Digital ElectronicClock/ Calendar in 2 hours. "Boeing747 Readout" Hour -Minute --Second-Month/Day. Assembly divided steps-corresponding parts envelopers U.S.made -Walnut Cabinet. Details Free!Professional Merchandise Center, 220Fifth Avenue, New York, NY 10001.

EVERYTHING you always wanted toknow about service contracts, butdidn't know who to ask. "THE SER-VICE CONTRACT COOKBOOK" only$15.00 postpaid when you askNATESA, Dept. SC, 5908 S. Troy,Chicago, IL 60629.

CONSTRUCTION PLANS. Digitaltachometer, regulated power supply,others. Send 25 cents for listing. MI-KRONICS, P.O. Box 338, Dundee, Ill.60118.

For Sale: One-man shop, Zenith Deal-er -in beautiful valley of Mont. Wantto retire. John Mednansky, Box 259,Stevensville, MT. Ph. 777-5111.

MUST SELL: Complete inventory ofparts and test equipment for TV ser-vicing. Most equipment & parts lessthan one year old and of latest design.Includes Sam's Photofacts, mostlyB & K equipment, & several parts kitsand new tubes. Total approx. $6,500worth. Write-Ron's TV, R.R., BlackRiver Falls, WI 54615. Call -715-284-9569.

Magnets. All types. Free magneticstrip with any order from these spe-cials. Twenty disc, or ten bar, or twostick, or eight assorted magnets. $1.00.Magnets, 8825-FET Allenwood, Ran-dallstown, Maryland 21133.

TV Ping-Pong Game. Plays throughyour set's antenna terminals. Plans$3.25. Also available: 4 -channel digitalscope plans and others. ARS SYS-TEMS, P.O. Box 1922E, Sunnyvale,CA 94088.

SUBSCRIBE NOW:EVERYTHING YOU'VE ALWAYS WANTED TO

KNOW ABOUT YOUR

TelephoneBUT DIDN'T KNOW WHO TO ASK

A UNIQUE REFERENCE GUIDETO THE INSIDE STORY

FROM -HE HOBBEST TO THE TECHNICIANCurrent News Items Plans IllustrationsStories History Comics Facts GamesCode Numbers Projects And Many More

LEARN TIE SECRETS OF YOUR TELEPHONE

FACTS HEVER PUBLISHED FOR THE PUBLICOre sear ..ubseription unt, S Vim)

Uld.1;iMM11°A'a M.CromM.M.TresiMgfnV7 E eoM...,...

Wanted

Wanted: Picture tube rebuildingequipment and supplies. Call or write:George Antimisiaris, 20 Coleville Road,Wayne, NJ 07470. (201) 839-4925.

COLLECTOR WANTS: Collections ordealer's stock of 78 rpm records -jazz,blues, country; 1925 to 1940. Also oldcomic books. Will travel. Dunner, 11Golden Hills, Saugus, Mass. 01906.

Wanted: An extra instruction manualfor Winston Electronics CorporationDYNAMIC SWEEP CIRCUIT ANA-LYZER Model 820, or the present ad-dress of the Winston Electronics Cor-poration of Philadelphia. Philip But-ler, Box 581, West Brookfield, MA01585.

WANTED -ELECTRONIC TECHNI-CIAN, UNUSUAL OPPORTUNITYFOR ONE WELL QUALIFIED INCOLOR TV. TOP SALES AND SER-VICE SHOP HAS 40 YEAR REPU-TATION. WE MUST REPLACE RE-TIRING PARTNERS. MUST BEHONEST, EAGER TO LEARN, ANDENJOY SERVING PEOPLE. CON-TACT: WELLS & LaHATTE, VICKS-BURG, MS. 39180.

Educational Courses

REPAIR TV TUNERS -High Earn-ings; Complete Course Details, 12 Re-pair Tricks, Many Plans, Two Lessons,all for $2. Refundable. Frank Bocek,Box 3236, Ent., Redding, CA 96001.

FEBRUARY 1975. ELECTRONIC TECHNICIAN/DEALER 49

Ft. ow cm I,

AUTOMATIC

STAPLE GUNSCUT WIRE & CABLE

INSTALLATION COSTS. . . without cutting into insulation!SAFE! Grooved Guide positions wire forproper staple envelopment! Grooved DrivingBlade stops staple at right depth of penetrationto prevent cutting into wire or cable insulation!

No. T-18-Fits wires up to3/16" in diameter.

BELL,TELEPHONE,

THERMOSTAT,INTERCOM,BURGLAR

ALARMand other lowvoltage wiring.

Uses T-18staples with 3/16" round crown

in 3/8" leg length only.

No. T-25-Fits wires up to1/4" in diameter.

Same basic constructionand fastens samewires as No. T-18.

Also used forRADIANT

HEAT WIRE

Uses 1-25 stapleswith 1/4" round crown in 9/32",3/8", 7/16" and 9/16" leg lengths.;'

T-18 and 1-25 staples also available in Monel andwith beige, brown and ivory finish at extra cost.

No. T-75-Fits wires and cablesup to 1/2" in diameter.

RADIANT HEATCABLE,

OF CABLE,WIRE CONDUIT

COPPER TUBINGor any non-metallic

sheathed cable.Also used as

DRIVE RINGSin stringing wires.

Uses T-75 staples with 1/2"flat crown in 9/16", 5/8" and

7/8" leg lengths.

Arrow Automatic Staple Guns save 70% in timeand effort on every type of wire or cable fasten-ing job. Arrow staples are specially designed withdivergent -pointed legs for easier driving androsin -coated for greater holding power! All -steelconstruction and high -carbon hardened steelworking parts are your assurance of maximumlong -life service and trouble -free performance.

Ask your Electrical Supply Dealeror write for further details.

Saddle Brook, New Jersey 07883

"Pioneers and PacesettersFor Almost A Half Century"

READERS

SERVICE INDEX

ADVERTISER'S INDEX

101 Antenna Corp. of America 43

102 Arrow Fastener Co., Inc. 50

103 B & F Enterprises 44

104 B & K Division Dynascan Corp. 21

105, 125 Book Club Tab Books 16.19, 47

106 Cornell Electronics Co. 46

107 Edsyn, Inc. 41

108 Fordham Radio Supply Co., Inc. 50

GTE Sylvania, Electronic

Components 5

General Electric Co., Tube

Division 35

109 Heath Co., The 37

110 Hickok Electrical Instruments,

Co. 6

111 International Rectifier Corp. 42

112 Leader Instruments

Corporation Cover 3

113 Mallory Distributor Products Co. 3

114 Motorola Training Institute 41

115 Mountain West Alarm Supply Co. 50

117 Oelrich Publications 45

116 Oneida Electronics Mfg. Co. 45

118 PTS Electronics, Inc. Cover 2

119,

121

122

123

124

126

127

128 Triplett Corporation Cover 4

129 Ungar, Division of Eldon

Industries 36

130 Wahl Clipper Corporation 43

131 Weller-Xcelite Electronics

Division

Winegard Company

132 Zenith Radio Corp.

120 Philips Test & Measuring

Instruments, Inc. 10

Qualitone Industries, Inc. 46

RCA Electronic Instruments 14

RCA Picture Tube Distributor 1

RMS Electronics, Inc. 50

Rohn Manufacturing 11

South River Metal Products 44

Telematic, Div. UXL Corp. 46

15

7

39

MOVING? BE SURETO LET US KNOW

YOUR NEW ADDRESS.

DISCOUNTTEST

EQUIPMENTSPECIALISTS

HICKOK

r.1CC)1 RCAEICO

COMPLETE LINE OF ELECTRONIC SUPPLIES

ICC/Mullard & Raytheon TubesTelematic Test Rigs

FREE CATALOGQUOTATIONS ON REQUEST

FORDHAMRadio Supply Co., Inc.

558 Morris Ave., Bronx, N.Y. 10451Tel. (212) 585-0330


FREE ALARM CATAFull line of professional burglar andfire alarm systems and supplies. 96pages, 450 items. Off the shelf delivery,quantity prices.

OG

ZXX\ mountain west alarm ..w4' I

W 4215 n. 16th st., phoenix, az. 85016


minibut BIG in performance

Two -Way VHF/UHF Hybrid Splitter,ItHS-20U/MM from RMS, makerof the "Non-Corrodables." Theoutstanding performer mini -housedin a zinc die-cast, completelysealed unit. Weather-proof forindoor/outdoor use. Goes into themost difficult installations.

Systeas teeipmeet

RMS ELECTRONICS, INC.50 Antin Place, Bronx, N.Y. 10462Tel. (212) 892-6700




ELECTRONICTECHNICIAN/DEALER

COMPLETE MANUFACTURER S' CIRCUIT DIAGRAMSAND TECHNICAL INFORMATION FOR 5 NEW SETS

SCHEMATIC NO. SCHEMATIC NO.

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COPYRIGHT 1975 BY ELECTRONIC TECHNICIAN/DEALER 1 EAST FIRST STREET. DULUTH. MINNESOTA 55802

20 VPPVest.25

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1569AIRLINEColor TV ModelGAI-12103B

FEBRUARY 1975

ELECTRONIC 5-7=4(7iica yicTECHFaCIANMEALER

COMPLETE MANUFACTURERS' CIRCUIT DIAGRAMSAND TECHNICAL INFORMATION FOR 5 NEW SETS

VHF TUNER 94A383-311111 IF STRIP r'....._ LI/41A 1411

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COPYRIGHT 1975 BY ELECTRONIC TECHNICIAN/DEALER I EAST FIRST STREET. DULUTH. MINNESOTA 55802

1.2 PICRIC VIDEO LOW 1/2 50011. VIDEO LOW4VPP'7, LEVEL MOD 15VPP U LEVEL MOD.BRITE MIN PIN 14 BRITE MAX. PIN 14

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SYMBOL DESCRIPTION GENERAL ELECTRIC PART NO. C17028 -20040f, + 100-10%200v EP31X40L202 -39.75MHz trap EP36X108

R205 - IF AGC 250n EP49X142 L203 -47.25MHz trap EP36X13R206 - RF AGC 250n EP49X142 L207 -41.25MHz trap EP36X92R4I3- red drive L215 -4.5MHz trap EP36X111R433 - green drive EP49X141 L222 - choke ES36X751R453- blue drive DL301 -delay line EP36X105R606 - kill adj 50K EU49X35 L501 audio take off EP36X1068619 - chrome gain equal 51( ES49X627 L502 -quad EP36X107R623 -ACC adj 100K EP49X143 L617 - chrome 4.3MHz EP36X112R706- vent size 3.5M EP49X144 L701 - choke EP36X1198709 - ven center EP49X144 L1001- horiz osc hold EP35X2R1113- horiz center 150n EP49X147 T1201 - power oformer EP62X45R1315- HV adj 2K EP49X90 T1202 -CRT filament EP64X34R1662- focus pot asm EP62X42 T1610- pincushion EP51X2C1206A -19009f, +100-10%40v EP31X42 T1700 -high voltage EP77X13C1206B- 19000f. + 100-10% 40v EP31X42 CB1201 - circuit breaker 1.5a ES10X18C1206C- 19000, +100-10%40v EP31X42 F1201- fuse 2.5a 125v slo blo EP10X13C1702A -4009f, + 100-10% 200v EP31X40 F1202 - fuse .5a 250v fast blo ES 10X43

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SECONDER, WAY. CTIORS TO ormrsonst HANWLESS 4000 HMISEEM MOM TO (WM INJURY 5014E 1...1 MGM NOLTROL IS WOOL.°RAW 114E B vOstme CERT.. 117,0115 Of TIM 1441 00.71044411*344 011C0.41 04101414001 YID (Erin.[ CARTOON M.110

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USE OF SUBSTITUTE REPLACEMENT PARTS WHICH DO NOT HAVE THE SAME SAFETY CHARACTERISTICS AS RE-COMMENDED IN FACTORY SERVICE INFORMATION MAY CREATE SHOCK, FIRE OR OTHER HAZARDS.

COPYRIGHT 1975 BY ELECTRONIC TECHNICiANADEALER 1 EAST FIRST STREET, DULUTH. MINNESOTA 55802

1571

T

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Ecrao 7fi,FEBRUARY 1975COMPLETE MANUFACTURERS' CIRCUIT DIAGRAMSAND TECHNICAL INFORMATION FOR 5 NEW SETS

177,7T,P1.171. 111111111111111111,,P111 rrawri---4pi,,RTIT ompirlit $111.wil

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COPYRIGHT 1975 BY ELECTRONIC TECHNICIAN' DEALER 1 EAST FIRST STREET. DULUTH. MINNESOTA 55802

1572AIRLINETV ModelsGAI-1 1 1 15A,BGAI-1 1 155A,B

FEBRUARY 1975

FLEEDZINTE rri-VaTG.4^1

COMPLETE MANUFACTURERS' CIRCUIT DIAGRAMSAND TECHNICAL INFORMATION FOR 5 NEW SETS

SYMBOL DESCRIPTION AIRLINE PART NO.

C603-250/200/1501+1, 165v. elect .67A30-11L301 - coi147.25MHz trap. . 72A415-2L306- coil detect 72A316-15L310- coil 4.5MHz trap 72A317-9L501 - coil horiz lock 94A480- 1T201 - xformer audio output 79A172-1T401A, B - yoke deflect ... 94A372-3T501 - xformer, horiz driver .72A417-1T503- xformer horiz output 79A166-2

0101

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tuner VHF GA1 11115A. GA1 11155A 94A433-2tuner VHF GA1 11115R GA1 111558 94A434-2

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INCLUDED SPECIFICALLY FOR SAFETY PURPOSES. FOR CONTINUED PROTECTION.

NO CHANGES SHOULD BE MADE TO THE ORIGINAL DESIGN. REPLACEMENT PARTS

MUST BE IDENTICAL TO THOSE USED IN THE ORIGINAL CMCUIT. SERVICE SHOULD

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COPYRIGHT 1575 BY ELECTRONIC TECHNICIAN/DEALER I EAST FIRST STREET. DULUTH. MINNESOTA 55802

LEADER5" Quality Scopes

Cost Less!

LBO -5065" Dual Trace/Dual ChannelAutomatic Triggered ScopeAn orstanding value -hat doesyour work automatically ... withauto hztl sweep, auto .ert'l inputgain and auto trigger (TV -V andTV -I-) to reduce errors. Hassep.is mul sweep mode display;X5 mag; X -Y cisplay; cirect RF in-put, vectorscopic display for colorphase adj.. with 10 Mhz b'width:10rtiV to 20Vo-p/cm ver'l sensi-tivity in 11 calib. steps. PCboard construction assures highreliability. Is beautifu ! Completewith 2 probes, 2 adapters, lead.plug & clips.

A Trend Setter! $569.95

While the Others Keep Raising Prices,Leader Fights Inflation to Save You Money

LBO -501

5" Triggered Scopew/Calibrated Input& Time BaseA professional grade solid stateinstrument recommended by theexperts. Vertical input is calibra-ted (v/cm) fo, high accuracy. -Iztldeflection is time calibrated, withtriggered sweep range from0.2µsec/cm :o 0.2sec/cm sweepoperable in free running or auto-matic. Offers 20mV to 10Vp-p/cmyen] sensitivity; 10MHz b'width:lighted graticule and tilt stand.A quality performer you candepend on. Complete with probe,leads and adapter

SAVE $60.00 NOW $399.95

e)IT ft

ON e lib

LBO -502

5' Triggered Scopew, Graded Scale

Solid state dependability lets youput 'his versatile scope to use formost every electronic purpose. Hasautcmatic and triggered sweep. 17steps calibrated, from 1µsec/cmtoo 2sec/cm plus X5 mag at0.24.sec/cm: 15M -Iz &width; 10mVto 20n-Vp-p/cm vert'l sensitivitywit -2-5 graded scale readings.Lab grade accuracy and pushoLtton ease of use make it a realwinner. Complete wit- probe. leadsand adapter.

SAVE $80.00 NOW $449.95

LEADER "Put Us To The Test"

db-

LBO -5115" Solid StateGeneral Service ScopeState-of-the-art design for lastingquality and performance. Featuresrecurrent sweep with automaticsync and calibrated ve,t I input: 0-140 phase control: TV -V and TV -Hinclusive with 4 sweep ranges to100KHz: 10MHz b.width. FET inpu:stages. DC coupling and push-pullamplifiers account for distortion -free displays and rock -like stabilityfor every use. Complete with probe.leads and adapter

SAVE $50.00 NOW $299.95

Instruments Corp. 151 Dupon: S:., Plainview. L.I., N.Y. 11803 (516) 822-9300


The reader that canstayon, and on, andon.The 603.The price of the Model 603V -O -M is only $173.

The one V -O -M you can forget aboutforgetting to turn off. The incredibleModel 603 FET V -O -M withexclusive Triplett Micro-PowerTMdraws only 10 uA, can stay onindefinitely without impairing per-formance. Ideal wherever frequenttest changes, interruptions, distrac-tions-or gremlins-keep your V -O -Mworking when you're not.

Truly outstanding features:1. Exclusive Triplett Micro -

Power (TMPTM) providesbattery life in excess of a yearfor carbon batteries with unitleft on continuously 24 -hoursa day.

2. Low -Power Ohms (1...P.11-^^)-6ranges with 70 mV powersource for in -circuit measure-ments without damage tocomponents.

3. FET V -O -M with PatentedAuto-Polarity-convenientand time -saving, always readsup scale.

Accurately measures electric andelectronic circuits on productionlines, in quality testing, during main-tenance, in service shops and oncalls, in the laboratory or classroom,in the field.

One range selector switch operatesthe unit. One probe handles allfunctions-AC, DC, MA, Ohms-anda simplified scale utilizes only 4 arcsfor all 44 ranges. The Low PowerOhm circuit permits fast circuitmeasurements without biasing semi-conductor device junctions. The

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Model 603 also has a unique,Patented Auto -Polarity circuit: pusha button, measure either plus or minusvoltages without switching leads.Make very fast voltage checks wherepolarity is known or doesn't matter.

For more information or a freedemonstration, call your Triplettdistributor or sales representative.

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For the name of the representativenearest you, dial toll free (800) 645-9200. New York State, call collect(516) 294-0990. Triplett Corporation,Bluffton, Ohio 45817.

TRIPLETTALL YOU'LL EVER NEED IN V -O -M's.

Triplett. The easy readers.. . . for more details circle 128 on Reader Service Card

pt% 111,1111111111% - worldradiohistory.com...pt% 111,1111111111% precision tuner service now...

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