Failure of the VHF 2 Transceiver

TASK 23-12-00-810-802-A
Failure of the VHF 2 Transceiver

1. Possible Causes

XCVR-VHF, 2 [1RC2]
wiring
C/B-COM NAV/VHF/2 or C/B-COM/VHF/2 [2RC2]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 23-12-00-740-001	BITE Test of the VHF System
ASM 231202
AMM 23-12-33-000-001	Removal of the VHF Transceiver
AMM 23-12-33-400-001	Installation of the VHF Transceiver

3. Fault Confirmation
Subtask 23-12-00-740-052-A

A. Test
Do the BITE test of the VHF system AMM 23-12-00-740-001.

NOTE: Do this test for the VHF 2 only.

4. Fault Isolation
Subtask 23-12-00-865-056-A

A. Table of the circuit breakers used in this procedure:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	COM NAV/VHF/2	2RC2	L04
** ON A/C NOT FOR ALL
121VU	COM/VHF/2	2RC2	L04

Subtask 23-12-00-810-051-A ** ON A/C NOT FOR ALL

B. If the test gives the maintenance message VHF2 TRANSCEIVER:

do a check of the circuit breaker (2RC2) status.

(1) If the circuit breaker is closed:

do a check for 28DC at pin AC/2 of the VHF 2 transceiver (1RC2) ASM 231202.

(a) If there is 28DC:

replace the XCVR-VHF, 2 [1RC2] , AMM 23-12-33-000-001 and AMM 23-12-33-400-001.

(b) If there is no 28DC:

do a check for a ground signal at pin AB/3D of the VHF 2 transceiver (1RC2) ASM 231202.

1 If there is no ground signal:

repair the wiring between the VHF 2 transceiver pin AB/3D and the ground terminal ASM 231202.

2 If there is a ground signal:

do a check of the wiring between the VHF 2 transceiver pin AC/2 and the circuit breaker 2RC2 ASM 231202.

a If there is no continuity:

repair the above wiring.

b If there is continuity:

replace the circuit breaker 2RC2.

(2) If the circuit breaker is open:

close it.

(a) If it opens again:

replace the VHF 2 transceiver AMM 23-12-33-000-001 and AMM 23-12-33-400-001.

1 If the fault continues:

do a check for a short-to-ground at the wiring between the VHF 2 transceiver pin AC/2 and the circuit breaker 2RC2 ASM 231202.

a If there is a short-to-ground:

repair the related wiring

b If there is no short-to-ground:

replace the C/B-COM NAV/VHF/2 or C/B-COM/VHF/2 [2RC2] .

(b) If the circuit breaker stays closed and the fault continues:

replace the VHF 2 transceiver AMM 23-12-33-000-001 and AMM 23-12-33-400-001.

Subtask 23-12-00-810-051-B ** ON A/C NOT FOR ALL

B. If the test gives the maintenance message VHF2 (1RC2):

do a check of the circuit breaker (2RC2) status.

(1) If the circuit breaker is closed:

do a check for 28DC at pin AC/2 of the VHF 2 transceiver (1RC2) ASM 231202.

(a) If there is 28DAC:

replace the XCVR-VHF, 2 [1RC2] , AMM 23-12-33-000-001 and AMM 23-12-33-400-001.

(b) If there is no 28DAC:

do a check for a ground signal at pin AB/3D of the VHF 2 transceiver (1RC2) ASM 231202.