MAINTENANCE OF AC-DC CONTROL BOX ASSEMBLY
Section I. ENCLOSURE COMPONENTS
4-1. FUEL TRANSFER PUMP RELAY K20.
a. Replacement. (See figure 4-1.) The fuel transfer
pump relay K20, (33, figure 4-1) is mounted on the right
side wall of the AC-DC control box assembly. It is
removed as follows:
MAINTENANCE PROCEDURE, SET
MAINTENANCE LOCKOUT SWITCH
BATTERIES. REMOVE EXTERNAL
BREAKER) AND DISCONNECTING
POWER CABLE FROM RECEPTACLE
J101 (120V RECEPTABLE).
Open door of AC-DC control box assembly
to gain access.
Remove and tag wires connected to the
Remove two screws (31) and nuts (32).
Remove relay (33).
Install relay (33) by mounting it to the side
wall of the enclosure with two screws (31)
and nuts (32).
Connect wires and remove tags.
Connect 24V DC to the small terminals on
the contactor in series with a SPST switch
as shown in figure 4-2.
Connect ohmmeter (Rx1) scale to the larger
terminals of the contactor.
Close the SPST switch. Ohmmeter should
Open the SPST switch. Connect ohmmeter
to the smaller terminals. Meter should read
approximately 60 ohms.
4-2. TERMINAL BOARD.
4-3. REPLACEMENET. The six terminal boards (26
and 30, figure 4-1) are mounted on the right side wall of
the enclosure (75). Replace as follows:
a. Removal. Tag and remove leads. Remove each
terminal board (26 and 30) by removing two screws (24
or 28) and nuts (25 or 29).
Diode (28) may also be tagged and
disconnected from terminal board
(30) at this time.
b. Replacement. Replace terminal board (26 or 30)
on the enclosure side wall by attaching two screws (24)
and nuts (25). Install diode (28) on terminal board (30)
and remove tags.
4-4. RESISTOR R116. Resistor R116 (38, figure 4-1)
is located on the right side wall of the enclosure (75).
a. Test. Disconnect either lead from resistor (38).
With an ohmmeter (set Rx1 scale) measure resistance.
It should be 5 ohms 1 ohm. If not, replace.
Remove two nuts (35, figure 4-1) which
secure resistor lugs (36) to the standoff (37).
Then remove resistor (38) from clip (41) and
separate lugs (36) from lead