TM 11-5820-803-12
Section III. ORGANIZATIONAL MAINTENANCE TROUBLESHOOTING AND REPAIR
5-5.
Troubleshooting
NOTE
Organizational maintenance troubleshooting of the PSK
Most maintenance actions involving
modem is required when an apparent malfunction or
front panel components require that
equipment damage is reported by the operator/crew.
power supply A2PS1 be removed to
Organizational maintenance troubleshooting actions are
facilitate access to the components.
detailed in table 5-2 Any trouble that is beyond the scope
Refer to paragraph 5-13 for power
of organizational maintenance shall be referred to higher
supply removal and reinstallation
category of maintenance.
procedures.
CAUTION
5-7.
Self-Test Failure
NEVER leave the bottom cover off
If the PSK modem fails to provide a specified indication
while the PSK modem is turned on
during self-test, carefully repeat the test in its entirety to
longer than necessary to make tests
ensure that the apparent failure was not caused by
and measurements. Power supply
operator error. If an indicator fails to illuminate when
A2PS1 may be damaged when the
specified and lamp replacement does not effect a
bottom cover (which arranges for
remedy, remove cover and check for loose or broken
proper airflow for cooling) is not in
leads or damaged socket. Repair or replace as required.
If the fault alarm fails to sound when specified, remove
place while the unit is turned on.
cover and connect VOM to verify that +5V de is present
at positive lead to alarm buzzer.
WARNING
If voltage is present, short negative lead of buzzer to
115V ac is present within the PSK
ground. If buzzer does not then sound, replace the
modem.
Perform all possible
alarm buzzer. If meter operation is erratic or consistently
maintenance with power removed. If
reads high or low, replace meter.
If the above
necessary to perform operations with
maintenance actions fail to correct the malfunction or if
covers removed and power on, use
the self-test failure symptom is other than those listed,
extreme care to avoid contact with
perform procedures of paragraphs 5-10, 5-11, and 5-12.
high voltage.
If failure symptoms remain, refer the malfunction to direct
support.
5-6.
Equipment Damage Repair
Organizational repair is limited to inspection and
5-8.
Noise Test Failure
replacement of blowers, fuse holders, indicator sockets,
If an unacceptable BER is calculated during noise
meter, and switches except for A1S5. If any of these
testing,' carefully examine the test setup, equipment
items are damaged, remove cover, tag leads, and
control settings, and repeat the test to ensure that the
replace the damaged component. Reconnect leads,
apparent malfunction was not caused by operator error.
reinstall cover, and perform self-test (para 3-5) to verify
If the BER remains unacceptable, refer the malfunction
operability. Refer any damaged items the repair of which
to direct support.
is beyond the scope of organizational maintenance to
higher category of maintenance.
Table 5-2. roubleshooting.
Malfunction
Probable cause
Corrective action
1. Equipment damage.
Mishandling.
2. Required indicator does not illuminate during
a. Operator error.
self-teat (indicator replacement does not rem-
b. Faulty wiring.
edy).
c. Damaged indicator socket.
3. Fault alarm does not sound during self-test.
Alarm buzzer defective.
4. Meter indicates incorrectly during self-test.
Meter defective.
5. Unacceptable BER during noise teat
Operator error.
6. Blower(s) not operating.
Blower defective.
7. Other malfunctions
a. Cards or connectors not properly
seated.
b. Power supply out of adjustment.
c. Thumbwheel switch assembly de-
fective.
5-2
