Tenma 72-7935 User manual

Table of Contents (1)
Table of Contents
Title Page
Overview
Inspection
Safety Information
Rules For Safe Operation
International Electrical Symbols
The Meter Structure
Functional Buttons
Measurement Operation
A. DC Voltage Measurement
B. AC Voltage Measurement
C. Measuring Resistance
D. Frequency and Duty Cycle Measurement
E. Measuring Diodes & Continuity
F. Capacitance Measurement
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Model 72-7935: OPERATING MANUAL

Table of Contents (2)
Title Page
Sleep Mode
General Specifications
Accuracy Specifications
A. DC Voltage
B. AC Voltage
C. Resistance Test
D. Frequency
E. Duty Cycle
F. Diodes and Continuity Test
G. Capacitance
Maintenance
A. General Service
B. Replacing the Battery
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Model 72-7935: OPERATING MANUAL

Overview
Overview
Warning
The Digital Multimeter Model 72-7935 (hereafter referred to as the meter) is a highly
reliable handheld measuring instrument featuring a variety of functions in a compact
design. Features include a 3-3/4 digit LCD display and dual A/D converters and will
measure AC/DC voltage, resistance, capacitance, frequency, duty cycle, diode and
continuity. Additional capabilities include relative mode, data hold, full icon display
and sleep mode.
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Model 72-7935: OPERATING MANUAL
To avoid the risk of injury from electric shock, read the “Safety Information”
and “Rules For Safe Operation” carefully before using the meter.

Unpacking Inspection
Inspection
This meter includes the following items:
Item
1
2
3
4
Description
English Operating Manual
Built-In Test Lead
Vinyl Holder
3V Button Battery (CR2032)
Qty
1 piece
1 pair
1 piece
1 piece
In the event items missing or damaded, please contact your dealer immediately.
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Model 72-7935: OPERATING MANUAL

Safety Information
Safety Information
This Meter complies with the standards IEC61010: in pollution degree 2, overvoltage
category (CAT. II 300V) and double insulation.
CAT. II: Local level, appliance, PORTABLE EQUIPMENTetc., with smaller transient voltage
overvoltages than CAT. III
Use the Meter only as specified in this operating manual, otherwise the protection
provided by the Meter may be impaired.
In this manual, a Warning identifies conditions and actions that pose hazards to the
user, or may damage the Meter or the equipment under test.
A Note identifies the information that user should pay attention on.
International electrical symbols used on the Meter and in this Operating Manual are
explained on page 9.
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Model 72-7935: OPERATING MANUAL

Rules For Safe Operation (1)
Rules For Safe Operation
Warning
To avoid possible electric shock or personal injury, and to avoid possible
damage to the Meter or to the equipment under test, adhere to the following
rules:
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Before using the Meter inspect the case. Do not use the Meter if it is damaged
or the case (or part of the case) is removed. Look for cracks or missing
plastic. Pay attention to the insulation around the connectors.
Inspect the test leads for damaged insulation or exposed metal. Check the
test leads for continuity.
Do not apply more than the rated voltage, as marked on the Meter, between
the terminals or between any terminal and grounding.
The rotary switch should be placed in the desired position prior to connecting
leads. This position should not be changed while leads are connected.
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Rules For Safe Operation (2)
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When using the Meter at an effective voltage over 60V DC 30V rms AC,
special care should be taken for there is danger of electric shock.
Use the proper terminals, function, and range for your measurements.
Do not use or store the Meter in an environment of high temperature, humidity,
explosive, inflammable and strong magnetic field. The performance of the
Meter may deteriorate after dampened.
When using the test leads, keep your fingers behind the finger guards.
Disconnect circuit power and discharge all high-voltage capacitors before
testing resistance, continuity, diodes or capacitance.
Replace the battery as soon as the battery indicator appears. With a low
battery, the Meter might produce false readings that can lead to electric
shock and personal injury.
Remove the connection between the testing leads and the circuit being
tested, and turn the Meter power off before opening the Meter case.
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Rules For Safe Operation (3)
When servicing the Meter, use only the same model number or identical
electrical specifications replacement parts.
The internal circuit of the Meter shall not be altered at will to avoid damage
of the Meter and any accident.
Soft cloth and mild detergent should be used to clean the surface of the
Meter when servicing. No abrasive and solvent should be used to prevent
the surface of the Meter from corrosion, damage and accident.
The Meter is suitable for indoor use only.
Turn the Meter power off when it is not in use and take out the battery when
not using for a long time.
Periodically check the battery for leaks, a leaking battery will damage the
meter.
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Model 72-7935: OPERATING MANUAL

International Electrical Symbols
International Electrical Symbols
Low Battery
AC (Alternating Current)
Capacitance
Double Insulated
Warning. Refer to the Operating Manual
Conforms to Standards of European Union
Ground
DC (Direct Current)
Diode
Continuity Test
Fuse
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Model 72-7935: OPERATING MANUAL

The Meter Structure
The Meter Structure (see figure 1)
1. LCD Display
2. SELECT Button
3. RELATIVE Mode Button
4. DATA HOLD Button
5. Hz/DUTY Button
6. Rotary Switch
7. Black Test Lead
8. Red Test Lead ( figure 1)
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Model 72-7935: OPERATING MANUAL

Functional Buttons
Functional Buttons
Button Operation Performed
SELECT Press SELECT to switch between resistance, capacitance, continuity buzzer and
diode measurement modes; the Meter beeps. Resistance measurement is
default.
Press RELATIVE to enter and exit the REL mode in any measuring mode except
in frequency/duty cycle; the Meter beeps.
Press HOLD once to enter hold mode.
Press HOLD again to exit hold mode.
In Hold mode, is displayed and the present value is shown.
Press Hz/DUTY at DCV to step through DCV, frequency and duty cycle
measurement mode. on the LCD will disappear.
Press Hz/DUTY at ACV to step through ACV, frequency and duty cycle
measurement mode. on the LCD will disappear.
The Meter will be at DCV: 400mV orACV: 4V after stepping through frequency
and duty cycle measurement mode. Therefore it is necessary to turn the
rotary switch or turn off and on the Meter to resume to autoranging mode
when measuring higher voltage.
RELATIVE
DATA HOLD
Hz/DUTY
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Measurement Operation(1)
Measurement Operation
Make sure the Sleep Mode is not on if there is no display on the LCD after turning
on the Meter.
Make sure the Low Battery Display is not on, otherwise false readings may
occour.
Pay extra attention to the symbol which is located besides the input terminals
of the Meter before carrying out measeurement.
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Measurement Operation(2)
A. DC Voltage Measurement (see figure 2)
( figure 2)
Red Black
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Model 72-7935: OPERATING MANUAL

Measurement Operation (3)
To measure DC voltage, connect the Meter as follows:
1. Set the rotary switch to DCV range.
2. Connect the test leads across with the object being measured with red test lead
to the positive and black test lead to the negative.
The measured value shows on the display.
Note
The LCD displays the negative reading when the test lead connection is reversed.
When DC voltage measurement has been completed, disconnect the connection
between the testing leads and the circuit under test.
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Model 72-7935: OPERATING MANUAL

Measurement Operation (4)
B. AC Voltage Measurement (see figure 2 with dotted line)
Warning
To avoid harm to you or damage to the Meter from electric shock, please do
not attempt to measure voltages higher than 300V although readings may be
obtained and take extra care when measuring high voltage.
To measure AC Voltage, connect the Meter as follows:
1. Set the rotary switch to ACV range.
2. Connect the test leads across with the object being measured.
The measured value shows on the display
Note
The LCD displays the negative reading when the test lead connection is reversed.
When AC voltage measurement has been completed, disconnect the connection
between the testing leads and the circuit under test.
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Measurement Operation (5)
C. Measuring Resistance (see figure 3)
( figure 3)
Red Black
Hz/Duty
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Model 72-7935: OPERATING MANUAL

Measurement Operation(6)
Warning
To avoid damage to the Meter or to the devices under test, disconnect circuit
power and discharge all the high-voltage capacitors before measuring resistance.
Ω
Note
The test leads can add 0.1Ωto 0.3Ω of error to the resistance measurement.
To obtain precision readings in low-resistance, that is the range of 400Ω, short-
circuit the red and black test leads beforehand and record the reading obtained
(called this reading as X).
Then use the equation:
measured resistance value (Y) – (X) = precision readings of resistance.
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To measure resistance, connect the Meter as follows:
1. Set the rotary switch to range.
2. Connect the test leads across with the object being measured.
The measured value shows on the display.
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For high resistance (>1MΩ), it normally requires several seconds to obtain a
stable reading.
When there is no input, for example in open circuit condition, the Meter displays
“OL”.
When resistance measurement has been completed, disconnect the connection
between the leads and the circuit under test.
Measurement Operation(7)
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Model 72-7935: OPERATING MANUAL
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D. Frequency and Duty Cycle Measurement (see figure 3 with dotted line)
Warning
To avoid harm to you or damage to the Meter, do not attempt to measure
voltages higher than 60V DC or 30V rms AC although readings may be obtained.
The testing resolution may vary from the inputted frequency and waveform,
the Meter resolution is based on the sine wave.
Note
When Hz or Duty Cycle measurement has been completed, disconnect the
connection between the leads and the circuit under test.
Measurement Operation(8)
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To measure frequency and duty cycle, connect the Meter as follows:
1. Set the rotary switch to ACV or DCV range.
2. Press Hz/DUTY button select Frequency or Duty Cycle measurment mode.
3. Connect the test leads across with the object being measured.
The measured value shows on the display.
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