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DC VOLTS TEST
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 2000mV and measure the voltage across the 100 ohm resistor of Figure Ia. 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 ohm resistor of Figure Ib. 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, R12-R17, R21-R24,
and capacitor C3.
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 750VAC
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 750VAC 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 R1 - R6, R22.
b) Check that diode D1 is mounted as shown in the assembly instructions.
DC AMPS TEST
1) Set the range switch to 200 A and connect the meter as in Figure J. With R
should be about 90 A. Compare the reading to a known accurate meter.
2) Set the range switch and R
accurate meter.
Range Switch
2000 A
20mA
200mA
If any of the above tests fail:
a) Check the fuse.
b) Check the value and soldering of resistors R7, R8, and R9.
1k
9V
100
Figure Ia
as in the following table. Read the currents shown and compare to a known
A
R
Current (approx.)
A
10k
900 A
1k
9mA
470
19mA
123
10A DC
V mA
COM
9V
Figure Ib
123
10A DC
V mA
COM
Figure J
-9-
123
10A DC
V mA
10k
COM
100
equal to 100k
the current
A
R
A
Accurate
Meter
9V
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