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DIGITAL MULTIMETER M-92A
INTRODUCTION
This instrument is compact, battery operated, handheld 3 1/2 digit digital multi-
meter for measuring DC and AC voltage. DC and AC current, resistance, diode and
continuity test. The Dual-Slope A-D converter uses C-MOS technology for auto-
zeroing. Polarity selection and over-range indication full overload protection is
provided. It is specially designed with high stability for use on modern computerized
circuits and laboratory, workshop, hobby and home applications.
FEATURES
• Single 24 position easy to use rotary switch
• High sensitivity of 100μV
• Automatic over range indication with the “1” or “-1” displayed
• Automatic polarity indication on DC range
• All ranges fully protected
• Diode testing with 1mA fixed current
• Transistor hFE test (optional)
GENERAL CHARACTERISTICS
Maximum LCD display: 1999 counts (31/2 digits) with automatic polarity indication
Measuring Method: Dual-slope integration A-D converter system
Overrange Indication: “1” or “-1” figure only in the display
Maximum common mode voltage: 500V DC/AC rms
Reading rate: 2~3 reading per sec. (approximate)
Temperature for guaranteed accuracy: 23±5 °C.
Temperature Ranges: Operating 0 °C to 40 °C (32 °F to 104 °F); Storage -10 °C to
50 °C (14 °F to 122 °F)
Power Supply: One 9V battery (NEDA 1604 or 6F22 type or equivalent).
Low Battery Indication: to left of display.
Size: 85(W) × 165(D) × 32(H)mm.
Weight: 250g (including 9 Volt battery)
Accessories: Operating manual, set of test leads.
SPECIFICATIONS
Accuracies are: ± (% r No. of digits).
Guaranteed for 1 year: 23 °C ±5 °C, less than 75% R.H.
OPERATION
1. Switch the meter on and check the 9V battery, if the battery is weak, a
sign
will appear on the display. If this does not appear on the display, proceed as
below, see MAINTENANCE if the battery has to be replaced.
2. The mark or sign
next to the test lead jacks, is for warning that the input
voltage or current should not exceed the indicated values.
This is to prevent damage to the internal circuit.
3. The function switch should be set to the range which you want to test before
operation.
DC Voltage Measurement
1. Connect the BLACK test lead to the COM jack and the RED test lead to the V/Ω
jack.
2. Set the FUNCTION switch to the “V” range to be used and connect the test
leads across the source or load under measurement. The polarity of the RED
lead connection will be indicated at the same time as the voltage.
NOTE:
a) If the voltage range is not known beforehand set the FUNCTION switch to a
high range and work down.
b) When only the figure “1” is displayed, over range is being indicated and the
FUNCTION switch must be set to a higher range.
c) Do not apply more than 1000V to the input, indication is possible at higher
voltages but there is danger of damaging the internal circuitry
d) Use extreme caution to avoid contact with high tension circuits when measuring
high voltage.
Range
Accuracy
Resolution
200mV
±0.5% of rdg ±1 digit
100μV
2V
1mV
20V
10mV
200V
100mV
1000V
±0.8% of rdg ±2 digits
1V
Input impedance: 10MΩ on all ranges
Overload protection: 250V rms on 200mV range and 1000V DC or peak AC on
all other ranges.
AC Voltage Measurement
1. Connect the BLACK test lead to the COM jack and the RED test lead to the V/Ω
jack.
2. Set the FUNCTION switch to the “V” range to be used and connect the test leads
across the source or load under measurement.
NOTE:
• See DC Voltage measurement Note a), b).
• Do not apply more than 750V rms to the input. Indication is possible at higher
voltages but there is danger of damaging the internal circuitry.
• Use extreme caution to avoid contact with high tension circuits when measuring
high voltage.
Range
Accuracy
Resolution
2V
±0.8% of rdg ±3 digits
1mV
20V
10mV
200V
100mV
750V
±1.2% of rdg ±3 digits
1V
Input impedance: 10MΩ on all ranges
Frequency range: 40Hz to 400Hz
Overload protection: 750V rms or 1000V peak continuous on all ranges.
Indication: Average (rms of sine wave)
DC Current Measurement
1. Connect the BLACK test lead to the COM jack and the RED test lead to the mA
jack for a Maximum of 200mA. For a maximum of 20A move the red test lead
to the 20A jack.
2. Set the FUNCTION switch to the “A” range to be used and connect the test leads
in series with the load under measurement. The polarity at the RED test lead
connection will be indicated at the same time as the current.
NOTE:
a) If the current range is not known beforehand. Set the FUNCTION switch to a
high range and work down.
b) When only the figure “1” is displayed overrange is being indicated and the
FUNCTION switch must be set to a higher range.
c) The maximum input current is 200mA or 20A depending upon the jack used
excessive current with blow the fuse which must be replaced. The 20A range is
not protected by a fuse. The fuse rating should be 0.2A and no more to prevent
damage to the internal circuitry.
Range
Accuracy
Resolution
2mA
±1.2% of rdg ±3 digits
1μA
20mA
10μA
200mA
±2% of rdg a ±3 digits
100μA
20A
±3% of rdg ±7 digits
10mA
Overload protection: F 0.2A/250V fuse. (20A range not fused)
Maximum input current: 20A, 15sec.
AC Current Measurement
1. Connect the BLACK test lead to the COM jack and the RED test lead to the mA
jack for a maximum of 200mA. For a maximum of 20A, move the red test lead
to the 20A jack.
2. Set the FUNCTION switch to the “A” range to be used and connect the test lead
in series with the load under measurement.
NOTE:
The maximum input current is 200mA or 20A depending upon the jack used.
Excessive current will below the fuse which must be replaced. The 20A range is
not protected by a fuse. The fuse rating should be 200mA and no more to prevent
damage to the internal circuit.
The maximum terminal voltage drop is 200mV.
Range
Accuracy
Resolution
2mA
±0.8% of rdg ±1 digit
1μA
20mA
10μA
200mA
±1,2% of rdg ±1 digit
100μA
20A
±2% of rdg ±5 digits
10mA
Overload protection: F 0.2A/250V fuse. (20A range not fused.)
Frequency range: 40Hz to 400Hz.
Maximum input current: 20A, 15sec.
Indication: Average (rms of sine wave)
Resistance Measurement
1. Connect the BLACK test lead to the COM jack and the RED test lead to the V/Ω
jack. (Note: The polarity of the RED test lead is “+”).
2. Set the FUNCTION switch to the Ω range to be used and connect the test leads
across the resistance under measurement.
NOTE:
a) If the resistance value being measured exceed the maximum value of the range
selected, an overrange indication will be displayed “1”, select a higher range.
For Resistance of approximately 1MΩ and above. The meter may take a few
seconds to become stable. This is normal for high resistance readings.
b) When the input is not connected, i.e. at open circuit, the figure “1” will be
displayed for the overrange condition.
c) When checking in–circuit resistance, be sure the circuit under test has all power
removed and that all capacitors are fully discharged.
GB
