TM109902 (5/03) 3-7
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C OMMAND S YSTEMS D IVISION
(4) Insert replacement. Ensure component orientation is the same as that noted in step (2).
(5) Using fine-solder (against component shoulder on rim) heat chassis with iron [step (3)]
until a minimal amount of solder flows between chassis and rim.
(6) Replace attaching components removed in step (1).
E. Replacement of Power Transistors
(1) Unsolder leads and remove heat sink nut and washer. Remove transistor and insulator.
(2) Apply silicone thermal compound Wakefield #120 heat-conductive grease to both sides of
the insulator and re-install the insulator.
(3) Install replacement transistor. Re-install and tighten nut. After assembly remove any excess
compound on heat sink around transistor.
(4) With an ohmmeter verify an open circuit (> 10 megohms) between the metal mounting tab
and the mounting stud to which the nut is attached.
(5) Solder leads in place.
F. PC Board, Two-Lead Component Removal (Resistors, Capacitors, Diodes, etc.)
(1) Heat from component side of board until solder flows and lift one lead from board; repeat
for other lead and remove component (note orientation).
(2) Remove all solder from board holes using desoldering suction tool. Avoid runs on
trackside.
(3) Dress and form leads of replacement component; insert leads into board holes.
(4) Solder in place and clip leads on trackside of board.
G. PC Board, Multi-Lead Component Removal (ICs, etc.)
(1) Remove component by clipping each lead along one side. Clip off leads as close to the
board surface as possible. Lift and bend back component repeating until leads on other side
snap. Discard component.
(2) On trackside of board, straighten or clip off component leads.
(3) On component side of board melt the solder in each hole; using the desoldering suction tool
remove solder and clipped leads from each hole.
(4) Insert replacement component observing correct orientation.
(5) Solder component in place from the trackside of the board. Avoid solder runs. No solder is
required on contacts where no track exists.
The document reference is online, please check the correspondence between the online documentation and the printed version.
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