TASK 23-51-00-810-806
 Failure of the Audio Management Unit
 1. Possible Causes
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 - AMU (1RN)

 - wiring

 - C/B - COM/AUDIO/FLT/INTPH (9RN)

 - C/B - COM NAV/SELCAL (8RN)

 2. Job Set-up Information
______________________
 A. Referenced Information
 -------------------------------------------------------------------------------REFERENCE DESIGNATION -------------------------------------------------------------------------------
AMM 23-51-00-740-002 BITE Test of the Audio System AMM 23-51-34-000-001 Removal of the Audio Management Unit (AMU) (1RN) AMM 23-51-34-400-001 Installation of the Audio Management Unit (AMU) (1RN) ASM 23-51/02 ASM 23-51/03 ASM 23-51/04 ASM 23-51/06
 3. Fault Confirmation
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 A. Test Do the BITE test of the AMU-ACP (Ref. AMM TASK 23-51-00-740-002).
 4. Fault Isolation
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 A. Table of the circuit breakers used in this procedure:
 -------------------------------------------------------------------------------PANEL DESIGNATION IDENT. LOCATION -------------------------------------------------------------------------------49VU COM/AUDIO/FLT/INTPH 9RN G08 121VU COM NAV/SELCAL 8RN M04
 「一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一1 EFF : ALL ∞∞23-51-00∞∞∞∞∞∞∞∞∞∞Page 210
 Aug 01/01 CESR **ON A/C 001-001, 051-052,

 B. If the test gives the maintenance message AUDIO MANAGEMENT UNIT:
 - do a check of the circuit breakers (8RN and 9RN) status.
 (1) If the two circuit breakers (8RN and 9RN) are closed:
 - do a check for 28VDC at pins AC/9, 10 of the AMU (1RN) (Ref. ASM 23-51/06).
 (a) If there is 28VDC at the two pins:
 - do a check at the 28VDC POWER SUPPLY signal of each card of the AMU (1RN): . For the AMU Card 1, 28VDC at pin AC/1 of the AMU (1RN) (Ref. ASM 23-51/02) . For the AMU Card 2, 28VDC at pin AC/4 of the AMU (1RN) (Ref. ASM 23-51/03) . For the AMU Card 3, 28VDC at pin AC/5 of the AMU (1RN) (Ref. ASM 23-51/04).
 1 If there is 28VDC at each pin:
_
 - replace the AMU (1RN) (Ref. AMM TASK 23-51-34-000-001) and (Ref. AMM TASK 23-51-34-400-001).
 2 If there is no 28VDC at each pin:
_
 - do a check of the ground and repair the wiring between AMU (1RN) pins AC/7, 8 and the ground terminal (Ref. ASM 23-51/03) and (Ref. ASM 23-51/04).
 3 If there is no 28VDC at one of the pins:
_
 - replace the AMU (1RN) (Ref. AMM TASK 23-51-34-000-001) and (Ref. AMM TASK 23-51-34-400-001).
 a If the fault continues:
_
 - repair the wiring between that faulty pin and the first terminal block.
 (b) If there is no 28VDC at the two pins:

 - do a check of the ground and repair the wiring between AMU (1RN) pins AC/7, 8 and the ground terminal (Ref. ASM 23-51/03) and (Ref. ASM 23-51/04).

 (c) If there is no 28VDC at pin AC/9 of the AMU (1RN):

 - replace the AMU (1RN) (Ref. AMM TASK 23-51-34-000-001) and (Ref. AMM TASK 23-51-34-400-001).
 1 If the fault continues:
_
 - do a check of the wiring between AMU (1RN) pin AC/9 and the circuit breaker (9RN) (Ref. ASM 23-51/06).
 a If there is no continuity:
_ - repair the above wiring.
 「一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一1R EFF : 001-001, 051-052, ∞∞23-51-00∞∞∞∞∞∞∞∞∞∞Page 211
 May 01/05 CES b If there is continuity:

_ - replace the C/B - COM/AUDIO/FLT/INTPH (9RN).
 (d) If there is no 28VDC at pin AC/10 of the AMU (1RN):
 - replace the AMU (1RN) (Ref. AMM TASK 23-51-34-000-001) and (Ref. AMM TASK 23-51-34-400-001).
 1 If the fault continues:
_
 - do a check of the wiring between AMU (1RN) pin AC/10 and the circuit breaker (8RN) (Ref. ASM 23-51/06).
 a If there is no continuity:
_
 - repair the above wiring. b If there is continuity:
_
 - replace the C/B - COM NAV/SELCAL (8RN).
 (2) If the circuit breaker (9RN) is open:
 - close it.
 (a) If it opens again:
 - replace the AMU (1RN) (Ref. AMM TASK 23-51-34-000-001) and (Ref. AMM TASK 23-51-34-400-001).
 1 If the fault continues:
_
 - do a check for a short to ground at the wiring between AMU (1RN) pin AC/9 and the circuit breaker (9RN) (Ref. ASM 23-51/06).
 a If there is a short to ground:
_
 - repair the related wiring. b If there is no short to ground:
　
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