TROUBLESHOOTING PROCEDURES-continued

TM 11-5820-670-12

TROUBLESHOOTING PROCEDURES. (CONT)

3-9.

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

Step 2.

Check cables and connectors for proper mating and connections.

Reconnect all connectors as required.

If radio still does not retransmit after squelch adjustment and proper connecting,

Step 3.

receiver-transmitter or control unit on one or both radio sets is defective.

Remove and replace receiver-transmitters one at a time (para 3-11).

If retransmission'is still not possible after replacement of both receiver-

Step 4.

transmitters, control unit on one or both radio sets is defective.

Remove and replace control units one at a time (para 3-11).

Step 5.

Check aircraft intercommunications system and antenna system.

Refer to applicable aircraft electronic maintenance manual for checks

and corrective action.

17. Radio sets oscillate (rapid fluctuations of noise and sidetone) in RETRAN mode.

Check squelch adjustment (SQ ADJ) on both receiver-transmitters.

Adjust SQ ADJ on both receiver-transmitters (para 3-4).

18. Radio set does not operate with mode control switch set to HOME.

Step 1.

Check warning flags on homing indicator. If showing, there is insufficient signal

strength.

Change frequency to a local FM station with a closer range.

Reset all controls on control unit. If homing still does not work, receiver-

Step 2.

transmitter is defective.

Remove and replace receiver-transmitter (para 3-11).

If replacement does not correct malfunction, control unit is defective.

Step 3.

Remove and replace control unit (para 3-11).

Step 4.

Check proper operation of homing indicator.

Refer to applicable aircraft electronic maintenance manual for checks

and corrective action.

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