TM 1-1520-238-T-6
Change 5
9–581
9–288. TRIM CIRCUIT BREAKER (CB87) – DOES NOT STAY CLOSED OR 28 VDC IS NOT
9–288
PRESENT AT (A76): J1-Y AND J1-Z
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
TM 1-1520-238-T-7
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 TRIM circuit breaker (CB87) stay
closed?
YES
Go to step 5.
NO
Go to step 2.
2. On pilot center circuit breaker panel, open TRIM
circuit breaker (CB87). Set BATT/EXT PWR
switch to OFF. Check for short between (A76):
J1-Y and ground,
J1-Z and ground.
Does short exist?
YES
Go to step 4.
NO
Go to step 3.
3. Check for short between P463-y and ground.
Does short exist?
YES
Refer to TM 1-1520-238-T-7 to
troubleshoot flight control
system.
NO
Refer to TM 11-1520-238-23-2
to troubleshoot HARS (ADC).
4. Detach wire at CB87-2. Check for short between
(A76):
J1-Y and ground,
J1-Z and ground.
Does short exist?
YES
Repair shorted wire.
Go to paragraph 9–263.
NO
Replace TRIM circuit breaker
(CB87) (TM 1-1520-238-23).
5. Set BATT/EXT PWR switch to OFF. Check for
open between:
CB87-2 and (A76)J1-Y,
CB87-2 and (A76)J1-Z.
Does open exist?
YES
Repair open wire.
Go to paragraph 9–263.
NO
Replace TRIM circuit breaker
(CB887) (TM 1-1520-238-23)..
END OF TASK
