TM 11-6625-2632-14
normal indications in this procedure, proceed to testing
complete checkout procedure to be sure the test set is
and calibration (sec IV). If an abnormal indication
functioning properly.
After completion of checkout
appears, record the step at which a malfunction occurred
procedure, refer to the calibration requirements shown in
and proceed to the corresponding step in the
troubleshooting procedure. After repair, perform the
Table 5-2. Operational Check
Step
Action
Normal indication
If indication is abnormal
1
Using connector adapters, connect
the test set cables to antenna
jacks of two Radio Sets An/PRC-
90 known to be operating properly
2
Set function switch of transmitting
radio to BCN 243.0 and VOL
switch to minimum.
3
Set function switch of receiving radio
a. Audible tone in speaker of
a. Malfunction is in cables or
to VOICE/MCW 243.0 and VOL
receiving radio.
Proceed to
antenna coupler circuit.
switch to MAX.
step 3b.
Refer to table 5-3, step 3.
b. Observe test set meter. Needle
b. Malfunction is in detector
should indicate slightly in green
circuit or meter circuit.
area of dial marking. Proceed
Refer to table 5-3, step 4.
to calibration (see IV).
Table 5-3. Troubleshooting Procedure
Step
Action
Normal indication
If indication is abnormal
1
Partially disassemble test set to
remove panel from case (refer to
2
Remove
cover
from
detector
assembly housing (see III).
3
With test set connected, and switches
Meter indicating in green area of
Proceed to step 4 below.
set as in step 3 of table 5-2,
dial marking.
observe test set meter.
4
Using bench testing equipment,
See figure 4-1, schematic diagram,
Replace faulty part.
check:
for values.
NOTE
a. Continuity of transmitter and
If receiver wire is
receiver cables, connectors
replaced, calibration
J1 and J2, and receiver wire.
of test set is required
b. Resistance
values
of
individual components.
5-2
