-10-
RESISTANCE/DIODE TEST
1) Measure a resistor of about half of the full scale value of each resistance range. Compare the kit meter
readings to those from a meter of known accuracy.
2) Measure the voltage drop of a good silicon diode. You should read about 700mV. Power diodes and the
base to emitter junction of power transistors may read less.
If any of these tests fail:
a) Check the values and the soldering of resistors R1 - R6, and R18.
b) Check that transistor Q1 is mounted as shown in the assembly instructions.
h
FE
1) Set the range switch to h
FE
and insert a small transistor into the appropriate NPN or PNP holes in the
transistor socket.
2) Read the h
FE
of the transistor. The h
FE
of transistors varies over a wide range, but you will probably get a
reading between 100 and 300.
If this check fails:
a) Check that the transistor socket is aligned according to Figure 4-4.
b) Check the value and soldering of resistors R9, R21, and R22
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, R16.
b) Check that diode D1 is mounted as shown in the assembly instructions.
DC AMPS TEST
1) Set the range switch to 200
µ
A and connect the meter as in Figure 5-3. With R
A
equal to 100k
Ω
the current
should be about 90
µ
A. 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.
RANGE SWITCH
R
A
CURRENT (approx.)
2000
µ
A
10k
Ω
900
µ
A
20mA
1k
Ω
9mA
200mA
470
Ω
19mA
If any of the above tests fail:
a) Check the fuse.
b) Check the value and soldering of resistors R7, R8, and R*.
Figure 5-3
V
Ω
MA
COM
10ADC
