W DOC AIRBUS | TSM A320F

Ground Service Buses cannot be supplied from the External Power

TASK 24-42-00-810-803-A
Ground Service Buses cannot be supplied from the External Power

1. Possible Causes
  • RCPT-EXT PWR [20XG]
  • SW-MAINT BUS/ON [5XX]
  • wiring
  • RELAY-GND/FLT SELECT CTL [7XX]
  • CNTOR-AC SVCE BUS NORM SPLY [12XN]
  • CNTOR-AC GND SVCE SPLY [12XX]
  • RELAY-TR 2 OVHT [6XX]
  • TR-2 [1PU2]
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
AMM 24-32-51-000-001
Removal of the Transformer Rectifier
AMM 24-32-51-400-001
Installation of the Transformer Rectifier
AMM 24-41-51-000-001
Removal of the External Power Receptacle
AMM 24-41-51-400-001
Installation of the External Power Receptacle
AMM 24-42-00-861-001
Energize the Ground Service Network from the External Power
ASM 244201
AMM 24-42-55-000-001
Removal of the Contactors
AMM 24-42-55-400-001
Installation of the Contactors
AMM 24-51-55-000-001
Removal of the AC Service Bus Normal Supply Contactor
AMM 24-51-55-400-001
Installation of the AC Service Bus Normal Supply Contactor
3. Fault Confirmation
Subtask 24-42-00-710-054-A
A. Energize the Ground Service Network from the External Power AMM 24-42-00-861-001.
NOTE: Examine the external power supply-cable and the external power receptacle before you do the connection.
If you find corrosion or damage, or if the pins are not aligned correctly, replace the RCPT-EXT PWR [20XG] AMM 24-41-51-000-001 and AMM 24-41-51-400-001.
4. Fault Isolation
Subtask 24-42-00-810-052-A
A. If the above procedure confirms that the EXT PWR/NOT IN USE indicator light stays on:
  • Do a check of the position of the MAINT BUS/ON switch (5XX).
   (1) If the switch stays in the ON position:
  • is a check for 28VDC at pin A/B2 of the GND/FLT selection control relay (7XX) ASM 244201.
     (a) If there is no 28VDC:
  • Replace the SW-MAINT BUS/ON [5XX] .
       1 If the fault continues:
  • Do a check and repair the wiring between pin 2A of the MAINT BUS/ON switch (5XX) and pin A/B2 of the GND/FLT selection control relay (7XX) ASM 244201.
     (b) If there is 28VDC:
  • Do a check for 28VDC at pin B/12 of the AC service bus normal supply contactor (12XN).
       1 If there is no 28VDC:
  • Replace the RELAY-GND/FLT SELECT CTL [7XX] .
         a If the fault continues:
  • Do a check and repair the wiring between pin B/12 of the AC service bus normal supply contactor (12XN) and pin A/B3 of the GND/FLT selection control relay (7XX).
       2 If there is no 28VDC:
  • Do a check for 28VDC at pin B/3 of the AC ground service supply contactor (12XX).
         a If there is no 28VDC:
         b If the fault continues:
  • Do a check and repair the wiring between pin B/3 of the AC ground service supply contactor (12XX) and pin B/10 of the AC service bus normal supply contactor (12XN).
         c If there is 28VDC:
   (2) If the switch does not stay in the ON position:
  • Do a check for 28VDC at pin 1A or 1B of the MAINT BUS/ON switch (5XX) ASM 244201.
     (a) If there is 28VDC:
  • Replace the SW-MAINT BUS/ON [5XX] .
     (b) If there is no 28VDC:
  • Do a check for 28VDC between pins A/X2 and A/A2 of the TR 2 overheat relay (6XX).
       1 If there is 28VDC:
  • Replace the RELAY-TR 2 OVHT [6XX] .
       2 If there is no 28VDC:
  • Do a check for 28VDC between pin A/A2 or A/X1 of the TR 2 overheat relay (6XX) and the ground.
         a If there is no 28VDC:
  • Do a check and repair the wiring between pin 2 of the circuit breaker (6XG) and pins A/A2 and A/X1 of the TR 2 overheat relay (6XX) ASM 244201.
         b If there is 28VDC:
  • Do a check for 28VDC between pin A/X1 of the TR 2 overheat relay (6XX) and pin B/F of the TR 2 (1PU2).
         c If there is no 28VDC:
         d If there is 28VDC:
  • Do a check and repair the wiring between pin A/X2 of the TR 2 overheat relay (6XX) and pin B/F of the TR 2 (1PU2) ASM 244201.
Subtask 24-42-00-710-055-A
B. Do the procedure given in Para. 3.A.
[Rev.8 from Aug 2018] 2026.04.04 04:26:55 UTC
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