W DOC AIRBUS | TSM A320F

Failure of the Audio Management Unit

TASK 23-51-00-810-806-A
Failure of the Audio Management Unit

1. Possible Causes
  • C/B-COM NAV/SELCAL [8RN]
  • C/B-COM/AUDIO/FLT/INTPH or C/B-INT 1 + 2 [9RN]
  • AMU [1RN]
  • wiring
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
AMM 23-51-00-740-002
BITE Test of the Audio System
ASM 235102
ASM 235103
ASM 235104
ASM 235106
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)
3. Fault Confirmation
Subtask 23-51-00-740-060-A
A. Test
Do the BITE test of the Audio System AMM 23-51-00-740-002.
4. Fault Isolation
Subtask 23-51-00-865-052-A
A. Table of the circuit breakers used in this procedure:
PANELDESIGNATIONFINLOCATION
** ON A/C NOT FOR ALL
49VUCOM/AUDIO/FLT/INTPH9RNG08
** ON A/C NOT FOR ALL
49VUINT 1 + 29RNG08
** ON A/C ALL
121VUCOM NAV/SELCAL8RNM04
Subtask 23-51-00-810-055-A
B. If the test gives the maintenance message AUDIO MANAGEMENT UNIT:
  • Do a check of the circuit breakers ( C/B-COM NAV/SELCAL [8RN] and C/B-COM/AUDIO/FLT/INTPH or C/B-INT 1 + 2 [9RN] ) status.
   (1) If the two circuit breakers are closed:
  • Do a check for 28VDC at pins AC/9, 10 of the AMU [1RN] ASM 235106.
     (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] ASM 235102
    . For the AMU Card 2, 28VDC at pin AC/4 of the AMU [1RN] ASM 235103
    . For the AMU Card 3, 28VDC at pin AC/5 of the AMU [1RN] ASM 235104.
       1 If there is 28VDC at each pin:
       2 If there is no 28VDC at each pin:
  • Do a check of the ground and repair the wiring from the AMU [1RN] pins AC/7, 8 to the ground terminal ASM 235103 and ASM 235104.
       3 If there is no 28VDC at one of the pins:
         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 from the AMU [1RN] pins AC/7, 8 to the ground terminal ASM 235103 and ASM 235104.
     (c) If there is no 28VDC at pin AC/9 of the AMU [1RN] :
       1 If the fault continues:
  • Do a check of the wiring from the AMU [1RN] pin AC/9 to the circuit breaker C/B-COM/AUDIO/FLT/INTPH or C/B-INT 1 + 2 [9RN] ASM 235106.
         a If there is no continuity:
  • Repair the above wiring.
         b If there is continuity:
  • Replace the circuit breaker C/B-COM/AUDIO/FLT/INTPH or C/B-INT 1 + 2 [9RN] .
     (d) If there is no 28VDC at pin AC/10 of the AMU [1RN] :
       1 If the fault continues:
  • Do a check of the wiring from the AMU [1RN] pin AC/10 to the circuit breaker C/B-COM NAV/SELCAL [8RN] ASM 235106.
         a If the fault continues:
  • Repair the above wiring.
         b If the fault continues:
  • Replace the circuit breaker C/B-COM NAV/SELCAL [8RN] .
   (2) If the circuit breaker C/B-COM/AUDIO/FLT/INTPH or C/B-INT 1 + 2 [9RN] is open:
  • Close it.
     (a) If it opens again:
       1 If the fault continues:
  • Do a check for a short to ground at the wiring from the AMU [1RN] pin AC/9 to the circuit breaker C/B-COM/AUDIO/FLT/INTPH or C/B-INT 1 + 2 [9RN] ASM 235106.
         a If there is a short to ground:
  • Repair the related wiring .
         b If there is no short to ground:
  • Replace the circuit breaker C/B-COM/AUDIO/FLT/INTPH or C/B-INT 1 + 2 [9RN] .
   (3) If the circuit breaker C/B-COM NAV/SELCAL [8RN] is open:
  • Close it.
     (a) If it opens again:
       1 If the fault continues:
  • Do a check for a short to ground at the wiring from the AMU [1RN] pin AC/10 to the circuit breaker C/B-COM NAV/SELCAL [8RN] ASM 235106.
         a If there is a short to ground:
  • Repair the related wiring .
         b If there is no short to ground:
  • Replace the circuit breaker C/B-COM NAV/SELCAL [8RN] .
Subtask 23-51-00-740-061-A
C. Do the test given in Para. 3.
[Rev.8 from Aug 2018] 2026.04.04 04:25:43 UTC
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