Elenco Compact Digital Multimeter - Manual (Page 10)

DC AMPS TEST
1) Set the range switch to 200
μA and connect the
meter as in Figure Q. With R A equal to 100k
Ω the
current should be about 90 μA. Compare the
reading to a known accurate meter.
2) Set the range switch and R A as in the following
table. Read the currents shown and compare to a
known accurate meter.
If any of the above tests fail:
a) Check the fuse.
b) Check the value and soldering of resistors R7,
R8,R13,D2 and D3.
-9-
Figure Q
V ΩmA
COM
10A DC
123
Accurate
Meter
R
A
9V
AC VOLTS TEST
To test the ACV ranges, we will need a source of AC
voltage. The AC power line is the most convenient.
CAUTION: Be very careful when working with
120VAC. Be sure that the range switch is in the 200
or 600VAC position before connecting the test leads
to 120VAC.
1) Set the range to 200VAC and measure the AC
power line. The voltage should be about 120VAC.
Compare the reading to a meter of known
accuracy.
2) Set the range to 600VAC and measure the AC
power line. The voltage should be about 120VAC.
Compare the reading to a meter of known
accuracy.
If either if the above tests fail:
a) Check the values and the soldering of resistors
D1,R1-6 and R19.
b) Check that diode D1 is mounted as shown in the
assembly instructions.
Range Switch R
A
Current (approx.)
2mA 10k
Ω
900
μA
20mA 1k
Ω
9mA
200mA 470
Ω
19mA
DC VOLTS TEST
Figure O
1k Ω
10A DC
V ΩmA
COM
100 Ω
9V
123
Figure P
10k Ω
10A DC
V ΩmA
COM
100 Ω
9V
123
1) If you have a variable power supply, set the supply to about the
midpoint of each of the DCV ranges and compare the kit meter
reading to a meter known accuracy.
2) If you do not have a variable power supply, make the following two
tests:
a) Set the range switch to 2V and measure the voltage across
the 100
Ω resistor of Figure O. You should get about 820mV.
Compare the reading to a meter of known accuracy.
b) Set the range switch to 200mV and measure the voltage
across the 100
Ω resistor of Figure P. You should get about
90mV. Compare the reading to a meter of known accuracy.
If any of these tests fail:
a) Recheck the meter calibration.
b) Check the value and the soldering of resistors R1 - R6, R10 - R12,
R14 - R17, VR1, and capacitor C4.