TM 1-1520-238-T-6
9–544
9–262. 28 VDC – IS NOT PRESENT AT P769-A AND P769-J (cont)
9–262
8. Detach wire at CB1-1. Check for short between
CB2-1 and ground.
Does short exist?
YES
Go to step 9.
NO
Go to step 10.
9. Remove bus bar between CB1 and CB2. Check
for short between CB1 and ground.
Does short exist?
YES
Replace shorted MUX L PYL
INBD circuit breaker (CB1).
NO
Replace shorted MUX L PYL
OUTBD circuit breaker (CB2).
10. Attach CB2 and CB1 wire. Detach wire at
CB5-1. Check for short between (A77)J4-A and
ground.
Does short exist?
YES
Repair shorted wire between
CB1-1 and CB5-1.
Go to paragraph 9–249.
NO
Go to step 11.
11. Detach wire at CB6-1. Check for short between
CB5-1 and ground.
Does short exist?
YES
Go to step 12.
NO
Go to step 13.
12. Remove bus bar between CB5 and CB6. Check
for short between CB5 and ground.
Does short exist?
YES
Replace MUX R PYL INBD
circuit breaker (CB5)
(TM 1-1520-238-23).
NO
Replace MUX R PYL OUTBD
circuit breaker (CB6)
(TM 1-1520-238-23).
13. Attach CB5 and CB6 wire. Detach wire at
CB10-1. Check for short between (A77)J4-A and
ground.
Does short exist?
YES
Go to step 14.
NO
Repair shorted wire between
CB10-1 and CB6-1.
Go to paragraph 9–249.
14. Remove bus bar between CB5 and CB6. Check
for short between CB5 and ground.
Does short exist?
YES
Replace MUX FAB R circuit
breaker (CB9)
(TM 1-1520-238-23).
NO
Replace MUX FAB L circuit
breaker (CB10)
(TM 1-1520-238-23).
15. Check for 28 VDC at (A402)J32-H.
Is voltage present?
YES
Repair open wire between
P461-H and P769-J.
Go to paragraph 9–249.
NO
Go to step 16.
16. Set BATT/EXT PWR switch to OFF. Check for
short between P461-H and ground.
Does short exist?
YES
Go to step 17.
NO
Go to paragraph 9–23 to
troubleshoot dc electrical power
generation.
17. Check for short between (A77)J4-J and ground.
Does short exist?
YES
Go to step 18.
NO
Repair shorted wire between
P461-H and P769-J.
Go to paragraph 9–249.
