Model 72-7740/72-7745 - Farnell ?· 3 Overview This Operating Manual covers information on safety and…

Download Model 72-7740/72-7745 - Farnell ?· 3 Overview This Operating Manual covers information on safety and…

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  • Model 72-7740/72-7745

    Copyright 2004 Tenma Test EquipmentAll rights reserved

    Tenma Test Equipment405 S. Pioneer Blvd.Springboro,Ohio

  • 34456789



    1415 16171819 2021 222224242525252526


    Unpacking Inspection

    Rules For Safe Operation

    Title Page

    Table of Contents


    D. Continuity Test

    International Electrical Symbols

    AC Voltage Measurement

    Capacitance Measurement

    The Use of Relative Value Mode

    The Meter Structure

    Turning on the Display Backlight

    General Specifications



    Safety Information

    Rotary SwitchFunctional ButtonsDisplay SymbolsMeasurement Ranges


    Measurement OperationA.B.C.D. Testing for ContinuityE.F.G.H.I. Temperature MeasurementJ.

    Operation of Hold Mode

    The POWER ButtonThe BLUE Button

    Sleep Mode (Model 72-7740 only)

    Accuracy SpecificationsA. DC VoltageB. AC VoltageC.

    Selecting a Measurement Range Manual Ranging and Autoranging

    DC Voltage Measurement

    Measuring Resistance

    Frequency Measurement

    DC or AC Current Measurement

    Testing Diodes

    Measuring Duty Cycle

    Model 72-7740/72-7745: OPERATING MANUAL

  • Capacitance Frequency & Duty Cycle

    DC Current

    2828282929 30






    J. AC CurrentMaintenance

    A. General ServiceB. Testing the FusesC. Replacing the BatteryD. Replacing the Fuses

    RS232C Serial Port (Model 72-7745)A. RS232C Port CableB. Setting of RS232C Serial PortsC. System Requirements for

    Installing the serial Interface Program

    Diode Test


    E.F.G.H. Temperature

    Model 72-7740/72-7745: OPERATING MANUAL

  • 3


    This Operating Manual covers information on safety andcautions. Please read the relevant information carefullyand observe all the Warnings and Notes strictly.

    WarningTo avoid electric shock or personal injury, read theSafety Information and Rules for Safe Operationcarefully before using the Meter.

    Digital Multimeter Model 72-7740and Model 72-7745(hereafter referred to as the Meter) have autorange andmanual range options with maximum reading 3999. Theenclosure structure design adopted advanced co-injectiontechnique in order to provide sufficient insulation.

    In addition to the conventional measuring functions, thereis a RS232C standard serial port equipped with Model72-7745 for easy connection with computer to realizemacro recording and monitoring and capture of transientdynamic data, displaying change of waveform during themeasurement, providing data and evidence to engineeringtechnicians for scientific research.This is also a highlyapplied digital multimeter of good performance with fulloverload protection and backlight function. Model 72-7745also has true rms reading for AC voltage and AC currentmeasurements.

    Model 72-7740/72-7745: OPERATING MANUAL

  • Qty1 piece1 pair1 pair

    1 piece

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    DescriptionOperating ManualTest LeadTest Clip

    CAT IV: Primary supply level, overhead lines, cablesystems etc.


    Unpacking InspectionOpen the package case and take out the Meter. Check thefollowing items carefully to see any missing or damaged part:

    In the event you find any missing or damage, pleasecontact your dealer immediately.Safety InformationThis Meter complies with the standards IEC61010: inpollution degree 2, overvoltage category (CAT. III 1000V,CAT. IV 600V;)and double insulation.CAT. III: Distribution level, fixed installation, with smallertransient overvoltages than CAT. IV

    Use the Meter only as specified in this operating manual,otherwise the protection provided by the Meter may beimpaired.

    In this manual, a Warning identifies conditions andactions that pose hazards to the user, or may damagethe Meter or the equipment under test.

    A Note identifies the information that user should payattention to.

    International electrical symbols used on the Meter andin this Operating Manual are explained on page 6.

    Model 72-7745:CD-ROM (Installation Guide & Computer Interface Software)

    Point Contact Temperature Probe

    Model 72-7745:RS232C Interface Cable

    9V Battery (NEDA1604, 6F22 or 006P) (installed)

    Model 72-7740/72-7745: OPERATING MANUAL

  • Rules For Safe Operation

    To avoid possible electric shock or personal injury, and toavoid possible damage to the Meter or to the equipmentunder test, adhere to the following rules:

    l Before using the Meter inspect the case. Do not use theMeter if it is damaged or the case (or part of the case) isremoved. Look for cracks or missing plastic. Payattention to the insulation around the connectors.

    l Inspect the test leads for damaged insulation or exposedmetal. Check the test leads for continuity. Replacedamaged test leads with identical model number orelectrical specifications before using the Meter.

    l Do not apply more than the rated voltage, as marked onthe Meter, between the terminals or between anyterminal and ground.

    l The rotary switch should be placed in the correctposition and no change of range made duringmeasurement , to prevent damage of the Meter.

    l When working at an effective voltage over 60VDC or 30V rms AC, special care should be takenthere is danger of electric shock.

    l Use the proper terminals, function, and range for yourmeasurements.

    l Do not use or store the Meter in an environment of hightemperature, humidity, explosive, flammable andstrong magnetic field. The performance of the Metermay deteriorate after dampened.

    l When using the test leads, keep your fingers behind thefinger guards.

    l Disconnect circuit power and discharge all high-voltagecapacitors before testing resistance, continuity, diodes,current, or capacitance.

    l Before measuring current, check the Meters fuses andturn off power to the circuit before connecting the Meterto the circuit.

    l Replace the battery as soon as the battery indicator " "appears. With a low battery, the Meter might producefalse readings that can lead to electric shock andpersonal injury.

    l Remove test lead, temperature probe, RS232C interface



    Model 72-7740/72-7745: OPERATING MANUAL

  • cable and test clip from the Meter and turn the Meterpower off before opening the case.

    l When servicing the Meter, use only the same modelnumber or identical electrical specifications replacementparts.

    l The internal circuit of the Meter shall not be altered atwill to avoid damage of the Meter and any accident.

    l Soft cloth and mild detergent should be used to clean thesurface of the Meter when servicing. No abrasive andsolvent should be used to prevent the surface of the Meterfrom corrosion, damage and accident.




    The Meter is suitable for indoor use.Under the environment with high (+/-4kV) electrostaticdischarge, the Meter may not be operated as normalcondition. The user may require resetting the Meter.Remove the battery when not used for a prolongedperiod to avoid damage to the Meter.Please constantly check the battery as it may leakwhen it has been using for some time, replace thebattery as soon as leaking appears. A leaking batterywill damage the Meter.


    International Electrical Symbols

    AC (AlternatingCurrent)

    Deficiency of Built-InBattery

    DC (Direct Current) Continuity TestAC or DC Diode

    Grounding Capacitance Test

    Double Insulated Fuse

    Warning. Refer to theOperating Manual

    Conforms to Standardsof European Union

    Model 72-7740/72-7745: OPERATING MANUAL

    l Periodically check the battery as it may leak aftersome time. If leakage is apparent,the battery shouldbe immediately replaced to prevent damage.

  • The Meter Structure (see figure 1)

    (figure 1)

    1 LCD Display2 Functional Buttons3 Rotary Switch4 HzV Input Terminal:

    Input for voltage, frequency/duty cycle, resistance, diode,continuity and capacitance measurements.

    5 COM Input Terminal:Return terminal for all measurements.

    Input Terminal:Input for 0.1 A to 400.0mA current measurements andtemperature testing.

    7 10A Input Terminal:Input for 0.01A to 10.00A current measurements.


    Model 72-7740/72-7745: OPERATING MANUAL

  • 8

    Rotary SwitchThe table below provides information about rotary switchpositions.



    V DC voltage measurement range from 400.0mV to1000V orAC voltage measurement range from 4.000V to750.0V.

    Continuity test.Diode test.Resistance measurement range from 400.0

    Temperature in celsiusHz Frequency measurement range from 10.00Hz to

    10.00MHz.AC or DC current measurement range from

    A.mA AC or DC current measurement range from

    40.00mA to 400.0mA.A AC or DC current measurement range from

    4.000A to 10.00A.

    to 40.00M .

    Model 72-7740/72-7745: OPERATING MANUAL

  • Functional Buttons (1)


    The table below provides information about functionalbutton operation.Button Measuring

    FunctionOperation Performed

    POWER Any rotaryswitch


    Turn the power on and off.

    V Switches between AC and DCvoltage; the Meter beeps. DC isdefault.Switches between continuity anddiode and resistance andcapacitance measurements; theMeter beeps.Resistance is default.

    Switches between AC and DCcurrent range from 400.0 A to4000 A; the Meter beeps. DC isdefault.

    mA Switches between AC and DCcurrent range from 40.00mA to400.0mA; the Meter beeps. DC isdefault.

    A Switches between AC and DCcurrent range from 4.000A to10.00A; the Meter beeps. DC isdefault.Disable Sleep Mode feature.


    Model 72-7740/72-7745: OPERATING MANUAL


    Any rotaryswitch



    l Press RANGE to enter themanual ranging mode; the Meterbeeps.Manually selecting a range causesthe Meter to exit the Hold and RELmodes.l Press RANGE to step throughthe ranges available for theselected function; the Meter beeps.l Press and hold RANGE for 2seconds to return to autoranging;the Meter beeps.

    Hz 1. Press to start the frequencycounter; the Meter beeps.2. Press again to enter duty cyclemode; the Meter beeps.3. Press again to return to thefrequency counter mode; the Meterbeeps.Hz %

    V , ,mA or


    1. Press to start the frequencycounter; the Meter beeps.2. Press again to enter duty cyclemode; the Meter beeps.3. Press again to return to theprevious measurement mode; theMeter beeps.


    Any rotaryswitch

    positionexcept Hz

    Press to enterand exit the REL mode in anymeasuring mode except infrequency/duty cycle; the Meterbeeps.

    Any rotaryswitch


    Press HOLD H to enter and exitthe Hold mode in any mode, theMeter beeps.


    Functional Buttons (2)

    HOLD H


    Model 72-7740/72-7745: OPERATING MANUAL

  • Display Symbols (1)(see figure 2)

    Number Symbol Meaning1 AC Indicator for AC voltage or current.

    Model 72-7740: The displayed value is themean value.Model 72-7745:The displayed value isthe true rms value.

    2 TRMS Model 72-7745: Indicator for true rmsvalue.

    3 The Meter is in the auto range mode inwhich the Meter automatically selects therange with the best resolution.

    4 RS232C Data output. It is always on the LCD, butdata output is only in progress when theMeter is connected to the computer via theincluded RS232C Interface Cable.

    5 % Percent: Used for duty cycle measurements.6 Data hold is active.7 The REL is on to display the present value

    minus the stored value.8 The battery is low.

    Warning To avoid false readings,which could lead to possible electric shockor personal injury, replace the battery assoon as the battery indicator appears.

    9 Centigrade. The unit of temperature.10 Diode test.11 The continuity buzzer is on.


    2 3 4 5 6 7 8 910


    12 ~ 1617

    (figure 2)


    Model 72-7740/72-7745: OPERATING MANUAL

  • , k ,M

    :k :M :

    Ohm. The unit of resistance.kilohm. 1 x 10 or 1000 ohms.Megaohm. 1 x 10 or 1,000,000 ohms.



    Farad. The unit of capacitance.Microfarad. 1 x 10 or 0.000001farads.Nanofarad. 1 x 10 or 0.000000001farads.




    Hertz. The unit of frequency incycles/second.Kilohertz. 1 x 10 or 1,000 hertz.Megahertz. 1 x 10 or1,000,000hertz.

    V, mV V:mV

    Volts. The unit of voltage.Millivolt. 1 x 10 or 0.001 volts.


    A, mA, A:mA:

    Amperes (amps). The unit of current.Milliamp. 1 x 10 or 0.001 amperes.Microamp. 1x 10 or 0.000001amperes.

    17 Indicates negative reading.18 The input value is too large for the selected


    Measurement Ranges (1)

    The Meter has both manual range and autorange options:


    Display Symbols (1) (see figure 2)

    A measurement range determines the highest value the Metercan measure. Most Meter functions have more than one range.See Accuracy Specifications.

    A.Selecting a Measurement Range

    Choosing the correct measurement range is important:

    l If the range is too low for the input, the Meter displays toindicate an overload.

    l If the range is too high, the Meter will not display the mostaccurate measurement.

    B. Manual Ranging and Autoranging

    Model 72-7740/72-7745: OPERATING MANUAL

  • l In the autorange mode, the Meter selects the best range forinput signals.This allows you to switch test points without having to resetthe range.

    l In the manual range mode, you may select the range.This allows you to override autorange and lock the Meter in aspecific range.

    The Meter defaults to the autorange mode in measurementfunctions that have more than one range. When the Meter is inthe autorange mode,

    To enter and exit the manual range mode:

    1. Press RANGE.The Meter enters the manual range mode and turns off.Pressing RANGE increments the range. When the highestrange is reached, the Meter wraps to the lowest range.

    Measurement Ranges (2)

    Notel If you manually change the measurement range after entering

    the REL or Hold recording modes, the Meter exits thesemodes.

    l Under frequency/duty cycle and capacitance measurement,only autorange mode is available.

    2. To exit the manual range mode, press and hold RANGE fortwo seconds.The Meter returns to the autorange mode and is displayed.

    is displayed.


    Model 72-7740/72-7745: OPERATING MANUAL

  • Measurement Operation (1)

    A.DC Voltage Measurement (see figure 3)

    (figure 3)

    To avoid harm to you or damage to the Meter fromelectric shock, please do not attempt to measure voltageshigher than 1000VDC / 750VAC rms although readingsmay be obtained.

    The DC Voltage ranges are: 400.0mV, 4.000V, 40.00V, 400.0Vand 1000V. To measure DC voltage, connect the Meter asfollows:

    1. Insert the red test lead into the terminal and the blacktest lead into the COM terminal.

    2. Set the rotary switch to ; DC measurement is default orpress BLUE button to select DC measurement mode.

    3. Connect the test leads across with the object being measured.The measured value shows on the display.

    Notel In each range, the Meter has an input impedance of 10M.

    This loading effect can cause measurement errors in highimpedance circuits. If the circuit impedance is less than orequal to 10k , the error is negligible (0.1% or less).

    l When DC voltage measurement has been completed,disconnect the connection between the test leads and thecircuit under test, and move the test leads away from theinput terminals of the Meter.





    Model 72-7740/72-7745: OPERATING MANUAL

  • Measurement Operation (2)


    B. AC Voltage Measurement(see figure 4)

    (figure 4)

    the true root mean square value converter needs a longertime to stabilize.

    To avoid harm to you or damage to the Meter fromelectric shock, pleas...


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