TM 1-1520-238-T-6
9–428
9–178. MSL R INBD LCHR AC CIRCUIT BREAKER (CB21) – DOES NOT STAY CLOSED
9–178
OR CONTINUITY DOES NOT EXIST BETWEEN (A77): J2-31 AND J2-4
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 9-1427-475-20
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 MSL R INBD LCHR AC curcuit breaker
(CB21) stay closed?
YES
Go to step 2.
NO
Go to step 3.
2. Set BATT/EXT PWR switch to OFF. Check for
open between:
CB18-1 and CB21-1,
(A77)J2-4 and CB21-2.
Does open exist?
YES
Repair open wire.
Go to paragraph 9–172.
NO
Replace MSL R INBD LCHR
AC circuit breaker (CB21)
(TM 1-1520-238-23).
3. Open CB21 and set BATT/EXT PWR switch to
OFF. Check for short between (A77)J2-4 and
ground.
Does open exist?
YES
Go to step 4.
NO
Refer to TM 9-1427-475-20 to
troubleshoot HME.
4. Detach wire at CB21-2. Check for short between
(A77)J2-4 and ground.
Does open exist?
YES
Repair shorted wire.
Go to paragraph 9–172.
NO
Replace MSL R INBD LCHR
AC circuit breaker (CB21)
(TM 1-1520-238-23).
END OF TASK
