TROUBLESHOOTING PROCEDURES-continued

TM 11-5820-670-12

TROUBLESHOOTING PROCEDURES. (CONT)

3-9.

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

7. Radio set continues to tune after frequency is set (channel tone in headset does not stop).

Reset frequency on control unit. If radio set continues to tune, receiver-

Step 1.

transmitter, control unit, or wiring is defective.

Check wiring for improper installation or damage. If no apparent dis-

crepancies are noted, remove and replace receiver-transmitter

Step 2.

Reset frequency. If radio set continues to tune, control unit is defective.

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

8. Radio set inoperative (no sidetone or signals heard).

Step 1.

Check primary power circuit breaker for tripped open condition.

Reset circuit breaker.

Check all electrical connectors for proper mating.

Step 2.

Reconnect all electrical connectors properly.

Check control unit for proper settings. If radio set is still inoperative, control unit

Step 3.

or receiver-transmitter is defective.

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

If radio set is still inoperative, control unit is defective.

Step 4.

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

9. Excess hum heard in headset.

Check audio-cable shield for improper grounding.

Step 1.

Refer to applicable aircraft electronic maintenance manual for checks

and corrective action.

Step 2.

Check aircraft intercommunications system for discrepancies.

Refer to applicable aircraft electronic maintenance manual for checks

and corrective action.

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