TM 1-1520-238-T-6
9–501
9–231. LT NAV CIRCUIT BREAKER (CB73) – DOES NOT STAY CLOSED OR
9–231
28 VDC IS NOT PRESENT AT P1-25
Tools:
Nomenclature
Part Number
Tool Kit, Electrical
SC518099CLA06
Repairer’s
Multimeter, Digital
AN/PSM-45
Personnel Required:
68X
Armament/Electrical Systems Repairer
One person to assist
References:
TM 1-1520-238-23
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 LT NAV circuit breaker (CB73) stay
closed?
YES
Go to step 4.
NO
Go to step 2.
2. Open CB73 and set BATT/EXT PWR switch to
OFF. Check for short between P1-25 and
ground.
Does short exist?
YES
Go to step 3.
NO
Go to paragraph 9–55 to
troubleshoot navigation lights.
3. Detach wire at CB73-2. Check for short between
P1-25 and ground.
Does short exist?
YES
Repair shorted wire between
CB73-2 and P1-25.
Go to paragraph 9–220.
NO
Replace LT NAV circuit breaker
(CB73) (TM 1-1520-238-23).
4. Set BATT/EXT PWR switch to OFF. Check for
open between:
CB73-1 and CB59-1,
CB73-2 and P1-25.
Does open exist?
YES
Repair open wire.
Go to paragraph 9–220.
NO
Replace LT NAV circuit breaker
(CB73) (TM 1-1520-238-23).
END OF TASK
