TM 55-4920-401-13&P
Section III.
REPAIR PROCEDURES
4-9. Soldering. Use a minimum amount of heat
when unsoldering and resoldering components. Re-
solder components using 60/40 tin-lead rosin-core
solder (item 2, table 1-16). Also use a flux (item 8)
when soldering thermocouple wire. Isopropyl alco-
hol (item 4) may be used to remove excess flux.
4-10. Removal and Disassembly.
a. Removal of Trimmer Deck Assembly.
(1) Disconnect BH15184A power interconnect
cable from INTERCONNECT connectors.
(2) Remove screws around edge of trimmer
deck and lift trimmer deck assembly from case.
(3) See paragraph 4-11 for installation of
trimmer deck assembly.
b. Removal of Probe Controller Assembly.
(1) Disconnect BH15184A power interconnect
cable from INTERCONNECT connectors.
(2) Support tester lid and remove lid stop arm
screw (12, fig. 4-29).
(3) Remove screws (3) around edge of probe
controller deck.
(4) Lift controller assembly high enough to
gain access to components in probe controller com-
partment.
(5) Mark wires to SCRs and remove screws
holding terminal lugs to cathodes and unsolder
wires to gates.
(6) Unscrew SCRs from heatsinks.
(7) Remove four screws holding transformer
(2, fig. FO-8) to bottom of probe controller compart-
ment and remove probe controller assmebly, wire
harness, and transformer.
(8) See paragraph 4-12 for installation of
probe controller assembly.
c. Removal of Switch-Power Board.
(1) Open trimmer assembly per paragraph 4-
1 0 a
(2) Disconnect thermocouple connectors P13
(20, fig. 4-31) and P14 (21) cm side of card cage.
(3) Remove four screws (4, fig. FO-7) attach-
ing harness connectors J8 and
and remove the connectors.
(4) Remove three screws
J9 (5) to the board
(18) at each end of
the board that hold connectors P6 and P7 between
this board and the mother board.
(5) Remove the TEMPERATURE, RPM, and
STD DAY switch knobs and retaining nuts.
(6) Remove six screws (19) that are in line
with the above switches and remove the board.
(7) See paragraph 4-13 for installation of
board.
d. Removal of Probe Control and Function
Switch Board.
(1) Open probe controller assembly per para-
graph 4-10 b.
(2) Remove
connector J6 to
switch board.
(3) Remove
two screws (11, fig. FO-8) holding
the probe control and function
four screws (1) holding harness
connectors P12 and P13 to board.
(4) Note location of and unsolder compensator
chromel and alumel wires (white and green wires)
from T/C INPUT switch (22).
(5) Mark and unsolder following wires from
probe control and function switch board: (1) blue
wire from eyelet POLE 7; (2) red wire from eyelet
POLE 8; (3) blue wire from eyelet D7, P4; (4) red
wire from eyelet P3; and (5) red wire from eyelet
P8.
(6) Remove knobs (7) and seal nuts (9) from
SPREAD and FUNCTION SELECT switches and
remove board.
(7) See paragraph 4-14 for installation of
board.
e. Removal of Resistance and Insulation
Check Board.
(1) Open probe controller assembly per para-
graph 4-10 b.
(2) Remove two screws (23, fig. 4-38) holding
board to connector J6.
(3) Remove two screws (1, fig. FO-8) holding
harness connector P7 to board.
(4) Remove knobs (12) and seal nuts (14) from
INSULATION CHECK switch and RESISTANCE
& A/C INDICATOR CHECK switch and remove
board.
(5) Install board per paragraph 4-15.
4-35