TM 55-4920-244-14
18. Box Assembly
14.
Screw
10.
Clamp
19. Instruction Plate
15.
Washer
11.
Screw
16.
Printed Circuit Board
12.
Washer
17.
Screw
13.
Clamp
Figure 4-6-Continued.
will accommodate additional wire. Use No. 20
(4) Inspect fuse and rectifier holders
AWG or larger insulated copper wiring for re-
for damage, mounting security, and proper ten-
placement purposes.
sion of clips.
(5) Inspect wiring harness for breaks
(5) Separate all component at cold
in insulation or conductors, shrinking of insula-
soldered or corroded joints. Clean terminals and
tion or other signs of overheating in wiring, and
conductors of all solder and corrosion. Tin all
damage to connector.
surfaces to be soldered and resolder joint.
(6) Use a suitable tester to test
zener diodes and rectifiers. Replace any defect-
CAUTION
ive components.
Provide a heat sink on con-
(7) Use a decade resistance bridge or
ductors between end of lead
other precision resistance checker and make sure
of zener diode and precision
all resistors are within tolerance.
resistor bodies to prevent
(8) Check capacitors with a capaci-
damage from overheating
tor checker.
when soldering.
(9) Use a suitable continuity checker
to test for continuity of windings and check in-
(6) Replace any component on
sulation resistance between windings and trans-
printed circuit board with broken or scored leads.
former case with a megger.
Any component showing definite signs of over-
e. Repair.
heating should be replaced regardless of test in-
(1) Straighten connector pins on
dication.
transformer with needle nose pliers or suitable
tube pin straightener. Replace transformer if pins
CAUTION
are broken or show signs of shearing after
straightening. External damage is permissible
Install rectifier holders fac-
providing case remains sealed, proper mounting
ing in proper direction. Neg-
is not affected, and/or windings are not dam-
ative (-) end of outside rec-
aged as described in
above.
tifier holders face cable side
(2) Replace transformer if paint is
of printed circuit board;
scorched (brown or yellowish areas) or if pot-
positive (+) end of inside
ting compound is leaking at seams or openings.
rectifier holders also face
(3) Replace printed circuit board if
the cable side.
any of the following conditions exist:
(a) Separation of plies in board
(7) Replace fuse and rectifier hold-
material.
ers if damaged. Resolder terminals if corroded
(b) Cracks, over 1/8 inch in
or hose. Clips may be carefully pinched together
length, or extending into component mounting
if required to restore tension. Replace rectifier
area or extending into a printed conductor path.
holders if worn or damaged to prevent rectifiers
(c) Carbonized paths between
being installed facing in wrong direction.
components, printed conductors, or mounting
(8) Replace power lead cable if con-
areas.
nector is damaged or if wiring shows deteriora-
(d) More than one printed con-
tion of insulation.
ductor cut, damaged, or separated from board.
(e) Separation of terminals from
(9) Single wires may be replaced in
board.
power lead cable. Use same size and type of
(4) Single printed conductors may
wire. Use white wire if proper color is not avail-
be replaced with point-to-point wiring if termi-
able and color code insulation terminal with
nals at each end of defective printed conductor
color(s) of original wire.
4-13
