MANUAL RANGING CAT III 600V DIGITAL MULTIMETER › productdoc › index › ...(General’s) DMM40...

MANUAL RANGING CAT III 600V

DIGITAL MULTIMETERUSER’S MANUAL

DMM40Please read this manual carefully and thoroughly before using this product.

TABLE OF CONTENTSIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Key Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3What’s in the Blister Pack . . . . . . . . . . . . . . . . . . . . . . . . . 4Product Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 – 5Safety Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 – 8Setup Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Install Battery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . 9 – 14General Instructions. . . . . . . . . . . . . . . . . . . . . . . . 9 – 10

Maximizing Measurement Resolution . . . . . . . . . 9Holding Readings . . . . . . . . . . . . . . . . . . . . . . . . 10Turning on the Backlight . . . . . . . . . . . . . . . . . . 10

Measuring AC or DC Voltage . . . . . . . . . . . . . . . . . . . . . 11Measuring DC Current. . . . . . . . . . . . . . . . . . . . . . 11 – 12Measuring Resistance . . . . . . . . . . . . . . . . . . . . . 12 – 13Checking for Continuity. . . . . . . . . . . . . . . . . . . . . . . . . 13Checking the Integrity of a Diode . . . . . . . . . . . . . 13 – 14Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 – 15Operating & Maintenance Tips. . . . . . . . . . . . . . . . . 16 – 17

Replacing the Fuse. . . . . . . . . . . . . . . . . . . 16 – 17Warranty Information . . . . . . . . . . . . . . . . . . . . . . . . 17 – 18Return for Repair Policy . . . . . . . . . . . . . . . . . . . . . . . . . . 18

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INTRODUCTIONThank you for purchasing General Tools & Instruments’(General’s) DMM40 Manual Ranging CAT III 600V DigitalMultimeter. Please read this user’s manual carefully andthoroughly before using the instrument.

The DMM40 is designed for use in an industrial setting byHVAC/R contractors, building maintenance technicians, MRO(maintenance, repair and operations) personnel at processand power plants, electricians, and electrical/electronictechnicians.

The meter is affordable, reliable, easy to use, ruggedly builtand designed to meet the CAT III 600V safety standard.

KEY FEATURES• 6 functions, 19 ranges

• Measures 1) AC voltage over five ranges, 2) DC voltageover five ranges, 3) DC current over four ranges, and 4) resistance over five ranges

• Uses beeper to 5) verify integrity of diodes and 6) checkcircuits for continuity

• Large backlit 3-1/2 digit (2,000 count) LCD

• LIGHT (backlight) and data HOLD buttons

• Designed to meet CAT III 600V safety standard

• CE approved

• 1 year limited warranty

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WHAT’S IN THE BLISTER PACKThe meter is supplied in a blister pack with a cavity in therear. Inside the cavity is a pair of double-insulated 20AWGtest leads and a “9V” battery inside a plastic wrapper. Thisuser’s manual is supplied inside the fold-over blister card.

PRODUCT OVERVIEWFig. 1 shows the labels and positions of the controls,indicators and physical structures of the DMM40. Fig. 2shows all possible indications on the meter’s LCD. Familiarizeyourself with the functions and meanings of these controls,indicators and connectors before moving on to the SetupInstructions and Operating Instructions.

Fig. 1. The controls,indicators and physicalstructures of the DMM40.1. LCD

2. LIGHT button. Pressedbriefly, turns on displaybacklight. Pressed withbacklight on, turnsbacklight off.

3. HOLD button. Pressed once,holds measured value(freezes display). Pressedagain, releases display toshow real-time readings.

4. Rotary function switch

5. Jacks for test leads

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2

1

3

4

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Fig. 2. All possible display indications

SAFETY INSTRUCTIONS•WARNINGTo avoid possible electric shock or personal injury, and toavoid damaging the meter or the equipment under test:• Do not use the meter in any way not detailed in this manualor the meter's safety features may be compromised.

• Before using the meter, inspect the case. Do not use the meter if it is damaged. Look for cracks ormissing plastic. Pay particular attention to the area near thetest lead jacks.

• •WARNING Inspect the test leads for damaged insulationor exposed metal. Check the test leads for continuity.Replace damaged leads before using the meter.

• Verify the meter’s operation by measuring a known voltage.Do not use the meter if it operates abnormally. Protectionmay be impaired. When in doubt, have the meter checkedand serviced by a qualified technician.

• •WARNING Do not apply more than the rated voltage, asmarked on the front of the meter, between the terminals orbetween either terminal and ground.

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HOLDHOLD

• •WARNING Do not measure current above 600V inCategory III installations.

• •WARNING Do not measure voltage with the rotaryfunction switch in any resistance (ohms) or current position.Doo not measure current with the rotary function switch inany resistance position.

• Use caution when working with voltages above 42VACRMS,or 60VDC. These voltages pose a shock hazard.

• Use the proper terminals, function, and range for allmeasurements.

• •WARNING Do not operate the meter around explosivegas, vapor, or dust.

• •WARNINGWhen using the test leads, keep your fingersbehind the finger guards. Do not touch the metal probes ofthe test leads when making a measurement.

• When making connections, connect the black (–) test leadbefore connecting the red (+) test lead; whendisconnecting, disconnect the red (+) test lead beforedisconnecting the black (–) test lead.

• Disconnect circuit power and discharge all high-voltagecapacitors before measuring/testing for resistance,continuity or diodes.

• Before making DC voltage measurements, verify that ACvoltages are not present by making measurements in ACvoltage mode. Then select a DC voltage range equal to orgreater than the AC range.

• Before measuring current, turn off power to the circuitbefore connecting the meter.

• Do not operate the meter with the case (or part of the case)removed.

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• Use only a “9V” Alkaline battery, properly installed in thebattery compartment, to power the meter. Do not userechargeable batteries.

• Replace the “9V” battery as soon as the low batteryindicator “ ” appears on the LCD. Operated with a weakbattery, the meter might produce false readings that couldlead to electric shock and personal injury.

• Remove the test leads from the meter before opening themeter meter’s or battery compartment.

Electrical Symbols Used On the Meterand In This Manual

Symbol Description Symbol Description

AC (Alternating FuseCurrent)

DC Double (Direct Current) Insulated

Caution, risk of Risk of danger. electric shock. ImportantHazardous information. voltage. Refer to the

manual.

Battery (Low battery) Earth groundwhen shown on display

Diode Continuity Beeper

AC or DC Complies with EU directives

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Symbol Description Symbol Description

Application and For measurementsremoval from made on building hazardous live equipment such conductors as distributionpermitted panels, feeders

and short branch circuits, and onlighting systems inlarge buildings.

SETUP INSTRUCTIONSINSTALL BATTERYThe DMM40’s battery compartment is located at the bottomrear of the meter.

To open the compartment, use a small Phillips-headscrewdriver to remove the three silver screws securing thebattery compartment cover. Put the screws and the cover tothe side and take care not to lose the small screws.

Remove the “9V” battery from the rear cavity of the blisterpack. Remove and discard its protective plastic wrapper. Plugthe battery into the wired socket inside the batterycompartment. The terminals of the battery and the socketmate in only one way, with the smaller male terminalplugging into the larger female terminal.

Replace the battery compartment cover and secure it with thethree Phillips-head screws.

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OPERATING INSTRUCTIONSGENERAL INSTRUCTIONSMaximizing Measurement Resolution. The DMM40 is amanual ranging multimeter with a total of 16 individualranges. In all but two cases (500VAC and 500VDC full-scale),each range is an order of magnitude wider or narrower thanthe range above or below it. For example, the four AC currentmeasurement ranges available are 200μA, 2000μA (2mA),20mA and 200mA. The Specifications section on pages 14and 15 lists the measurement ranges (and their resolutions)available for each of the four parameters—DC volts, AC volts,AC amps and resistance (in ohms)—measured by theDMM40.

To maximize the resolution of your readings, you shouldchoose the narrowest full-scale range that encompassesmost or all expected values of the target parameter withoutexceeding the upper limit of the range. For example, if youexpect that all of the DC voltages you will encounter during atroubleshooting session to be within 1V and 15V, choose the 0 to 20VDC measurement range. Why? Choosing the next-widest available range (0 to 200VDC) would yield readingswith unnecessarily low resolution. Choosing the next-narrowest range (0 to 2VDC) would cause too many readingsto exceed the upper limit of the range and produce overloadreadings.

If you do not know what values of your target parameter toexpect, initially choose the widest-available measurementrange for that parameter. If none of your measurementsproduce an overload reading (the number 1 on the LCD), thenswitch to the next-narrowest range. If none of yourmeasurements produces an overload reading in that range,

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then switch to an even narrower range.

The DMM40 provides two functions that can be applied tomeasurements and displays of all four measured parameters.

Holding Readings. Pressing the HOLD button (Fig. 1, Callout 3)“freezes” the measured value shown on the display andcauses the word to appear at its left. Pressing theHOLD button again releases the display to show real-timereadings and removes the indication.

Turning On the Backlight. Pressing the LIGHT button (Fig. 1,Callout 2) turns on the LCD’s bright white backlight, makingmeasurements much easier to read in dark spaces. Thebacklight will remain on indefinitely, until the LIGHT button ispressed again.

The LIGHT button is a true switch, and the DMM40 willrespond to its position whenever the meter is powered on. As a practical matter, what that means is that the meter will“remember” the last setting of the switch at each startup. Ifthe backlight was on when the meter was powered off, thebacklight will be activated automatically when the meter ispowered on the next time.

Since the backlight can be left on indefinitely, it is importantthat you remember to power off the meter by setting therotary function switch to the OFF position following eachmeasurement session. If you forget to set the switch to OFFbefore leaving the meter unattended, you risk accidentlydepleting the charge of the “9V” battery. The battery willdischarge even more quickly if it is left unattended with thebacklight on as well.

HOLD

HOLD

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MEASURING AC OR DC VOLTAGE WARNING

Do not measure any voltage higher than 500V. Doing so mayblow the meter’s internal fuse and/or damage the meter’sinternal circuitry.

(1) Set the rotary function switch to one of the five (DCvoltage) positions or two (AC voltage) positions. If youchoose the 500VDC or 500VAC position, the icon willappear at the upper left corner of the LCD (see Fig. 2) toalert you to the potential danger of measuring highvoltage.

(2) Plug the red test lead into the V/Ω/mA jack on the front ofthe meter and the black test lead into the COM jack.

(3) Touch the black test lead to the lower-potential point ofthe circuit under test, and the red test lead to the higher-potential point.

(4) Read the measured voltage amplitude on the LCD. If thetest leads are reversed, a minus sign will appear at the left of the displayed value. If the voltage is higher than the upper limit of the chosen measurement range, a 1 (indicating overload) will appear on the LCD. If thishappens, switch to a wider full-scale range.

MEASURING DC CURRENT WARNING

Before inserting test leads into a circuit, remove power fromthe circuit.

(1) Set the rotary function switch to one of the four(DC current) positions.

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(3) Connect the test leads in series with the device whosecurrent flow you wish to measure.

(4) Read the measured current amplitude on the LCD. If thetest leads are reversed, a minus sign will appear at the leftof the displayed value. If the current amplitude is greaterthan the upper limit of the chosen measurement range, a1 (indicating overload) will appear on the LCD. If thishappens, switch to a wider full-scale range.

MEASURING RESISTANCE WARNING

To avoid electrical shock or damage to the meter whenmeasuring resistance or continuity in a circuit, make sure thepower to the circuit is turned off and all capacitors aredischarged.

(1) Turn the rotary function switch to one of the five Ωpositions.


(3) Measure the resistance by touching the tips of the leadsacross the resistor or between the desired test points ofthe circuit, as shown below.

(4) Read the measured resistance on the LCD. If themeasured resistance is greater than the upper limit of theselected full-scale range, 1 will appear on the LCD to

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RED TEST LEAD BLACK TEST LEAD

indicate an overload. If this happens, switch to a widerfull-scale range. A 1 will also appear to indicate an opencircuit.

CHECKING FOR CONTINUITY(1) Turn the rotary function switch to the position. Until

the test leads are plugged into the meter’s front-paneljacks, 1 will appear on the LCD to indicate an open circuit.


(3) Touch the test leads to any two points of a circuit. If theresistance between those points is <(50 ± 25Ω), thebeeper will sound continuously. If there is no continuity (anopen circuit or a resistance greater than 75Ω between thetwo points), 1 will appear on the LCD and the beeper willnot sound.

CHECKING THE INTEGRITY OF A DIODE(1) Turn the function switch to the ( ) position. Until the

test leads are plugged into the meter’s front-panel jacks, 1 will appear on the LCD to indicate an open circuit.


(3) Connect the red test lead to the anode (positive terminal)of the diode to be tested, and the black test lead to itscathode (negative terminal).

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RED TEST LEAD BLACK TEST LEAD

(4) Read the forward bias voltage value on the LCD. A silicondiode typically has a forward bias voltage of 0.7V. Agermanium diode typically has a forward bias voltage of0.3V. A 0V reading in both directions indicates a shorteddiode. A reading of 1 indicates an open diode. In eithercase, the diode is defective and should be replaced.

SPECIFICATIONSParameter/ Specification ValueComponentAC voltage Measurement 0 to 200mV/2V/20V/200V/500V

rangesMeasurement 0.1mV/1mV/10mV/100mV/1Vresolutions

Measurement ±(2.5% of reading + 5 digits)accuracy

DC voltage Measurement 0 to 200mV/2V/20V/200V/500Vranges

Measurement 0.1mV/1mV/10mV/100mV/1Vresolutions


DC current Measurement 0 to 200μA/2mA/20mA/200mAranges

Measurement 0.1μA/1μA/10μA/100μAresolutions


Resistance Measurement 0 to 200Ω/2kΩ/20kΩ/200kΩ/2MΩranges

Measurement 0.1Ω/1Ω/10Ω/100Ω/1kΩresolutions


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SPECIFICATIONS (continued)Parameter/ ValueComponentContinuity threshold <(50 ± 25Ω)Overload protection level 600VAC/DCInput impedance 10MΩFrequency response 50/60HzIngress protection IP20(IP) ratingSafety rating CAT III 600VTest leads Double-insulated,

20 AWG, 1A max ratingDisplay No. of digits 3-1/2

Maximum 2000countSize 2.4 x 1 in. (62 x 26mm)

Digit height 0.68 in. (17mm)Operating temperature 32° to 122°F (0° to 50°C)@<75%RHOperating altitude (max) 6562 ft. (2000m)Dimensions 5.5 x 3.4 x 1.3 in.

(140 x 85 x 34mm)Weight (including battery) 6.9 oz. (196g)Power source (1) “9V” battery

(NEDA 1604/IEC 6F22)Battery life 100 hours (typical)

Note: Accuracy values stated for operation at 23° ±3°C @<70%RH

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OPERATING & MAINTENANCE TIPSWhen the icon appears at the lower left of the LCD (seeFig. 2), it’s time to replace the “9V” battery that powers themeter (although measurements will remain valid for severalhours after the icon first appears). To replace the battery,follow the instructions on p. 8.

Do not operate the DMM40 in the presence of a flammable orexplosive gas or near an arc welder or induction heater.

After subjecting the meter to a large change in ambienttemperature, wait at least 30 minutes before makingmeasurements to guarantee the accuracy of readings.

Remove the battery when storing the meter or when you donot expect to use it for an extended period of time (monthsrather than weeks).

Do not disassemble the DMM40 or immerse it in water.REPLACING THE FUSEThe DMM40 is equipped with a 200mA/250V cylindrical fusein series with the V/Ω/mA jack.

The fuse is located in the battery compartment, above the“9V” battery (see photo below).

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To replace the fuse, open the battery compartment byremoving the three screws securing its cover. Be careful notto shatter the glass of the blown fuse when removing it, andtake care not to lose the small screws after opening thecompartment.

WARRANTY INFORMATIONGeneral Tools & Instruments’ (General’s) DMM40 ManualRanging CAT III 600V Digital Multimeter is warranted to theoriginal purchaser to be free from defects in material andworkmanship for a period of one year. Subject to certainrestrictions, General will repair or replace this instrument if,after examination, the company determines it to be defectivein material or workmanship. The warranty period begins onthe date of purchase. You are encouraged to register yourproduct online. General will extend your warranty anadditional 60 days if you register atwww.generaltools.com/ProductRegistry.

This warranty does not apply to damages that Generaldetermines to be from an attempted repair by non-authorizedpersonnel or misuse, alterations, normal wear and tear, oraccidental damage. The defective unit must be returned toGeneral Tools & Instruments or to a General-authorizedservice center, freight prepaid and insured.

Acceptance of the exclusive repair and replacement remediesdescribed herein is a condition of the contract for purchase of this product. In no event shall General be liable for anyincidental, special, consequential or punitive damages, or forany cost, attorneys’ fees, expenses, or losses alleged to be aconsequence of damage due to failure of, or defect in anyproduct including, but not limited to, any claims for loss ofprofits.

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Register now at www.generaltools.com/ProductRegistry toreceive a 60-day extension to your warranty.

RETURN FOR REPAIR POLICYEvery effort has been made to provide you with a reliableproduct of superior quality. However, in the event yourinstrument requires repair, please contact our CustomerService to obtain an RGA (Return Goods Authorization)number before forwarding the unit via prepaid freight to theattention of our Service Center at this address:

General Tools & Instruments80 White StreetNew York, NY 10013212-431-6100

Remember to include a copy of your proof of purchase, yourreturn address, and your phone number and/or e-mailaddress.

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GENERAL TOOLS & INSTRUMENTS80 White Street

New York, NY 10013-3567PHONE (212) 431-6100 FAX (212) 431-6499

TOLL FREE (800) 697-8665e-mail: [email protected]

www.generaltools.comDMM40 User’s Manual

Specifications subject to change without notice©2013 GENERAL TOOLS & INSTRUMENTS

NOTICE - WE ARE NOT RESPONSIBLE FOR TYPOGRAPHICAL ERRORS.MAN#DMM4010/02/13

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