TM 1-1520-238-T-6
9–497
9–227. NAV VDU CIRCUIT BREAKER (CB91) – DOES NOT STAY CLOSED OR 28 VDC
9–227
IS NOT PRESENT AT P1-41 AND P1-42
Tools:
Nomenclature
Part Number
Tool Kit, Electrical
SC518099CLA06
Repairer’s
Multimeter, Digital
AN/PSM-45
Personnel Required:
68X
Armament/Electrical Systems Repairer
References:
TM 1-1520-238-23
TM 11-1520-238-23-2
WARNING
Turn off power before detaching or
attaching wires and connectors. High
current 28 VDC or 115 VAC is present.
Failure to do so could result in death or
serious injury.
1. On pilot ELEC PWR panel, set BATT/EXT PWR
switch to EXT PWR.
Does NAV VDU circuit breaker (CB91) stay
closed?
YES
Go to step 4.
NO
Go to step 2.
2. Open CB91 and set BATT/EXT PWR switch to
OFF. Check for short between:
P1-41 and ground,
P1-42 and ground.
Does short exist?
YES
Go to step 3.
NO
Refer to TM 11-1520-238-23-2
to troubleshoot video recorder
system.
3. Detach wire at CB91-2. Check for short
between:
P1-41 and ground,
P1-42 and ground.
Does short exist?
YES
Repair shorted wire.
Go to paragraph 9–220.
NO
Replace NAV VDU circuit
breaker (CB91)
(TM 1-1520-238-23).
4. Set BATT/EXT PWR switch to OFF. Check for
open between:
CB91-1 and CB89-1,
CB91-2 and P1-41,
CB91-2 and P1-42.
Does open exist?
YES
Repair open wire.
Go to paragraph 9–220.
NO
Replace NAV VDU circuit
breaker (CB91)
(TM 1-1520-238-23).
END OF TASK
