Lincoln Electric COMMANDER SVM153-A Service Manual page 122

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POWER MODULE (CHOPPER) PC BOARD/DIODE
MODULE REMOVAL AND REPLACEMENT (CONTINUED)
FIGURE F.31 – DIODE MODULE MOUNTING DETAILS AND TIGHTENING SEQUENCE
SPRING WASHER
PLAIN WASHER
FINGER TIGHT
5.0-10 IN-LBS.
DIODE MODULE REMOVAL
Refer to Figure F.31.
1. Remove the Power Module PC board as
described above.
2. Using the 7/16" wrench, remove the two
outer screws, spring washers, and large flat
washers from the diode module.
3. Using the 9/64" allen wrench, remove the
set screw from the center of the diode
module.
4. Remove the diode module from the heat
sink.
DIODE MODULE REPLACEMENT
Refer to Figure F.31.
The proper tightening sequence is required to
mount the diode module to the heat sink in
order to avoid warping the base plate. Apply
the proper torque to all fasteners.
TROUBLESHOOTING & REPAIR
2 TO 3
TURNS EACH
5.0-10 IN-LBS.
CAUTION
COMMANDER 500
12-18 IN.LBS.
30-40 IN.LBS.
1. Be sure the heat sink mounting surface is
clean, dry, and free of grease.
2. Apply a thin, even coat (.1 to .25mm or .004
to .010 in) of Penetrox A13 thermal joint
compound (T12837-1) to the diode module
base plate only, under the plastic body of the
module. Do not apply compound to the area
under the mounting holes.
3. Press the module firmly against the heat
sink, aligning the mounting holes.
4. Place a spring washer then a flat washer
over each outer mounting screw and insert
them into the holes. Insert the allen head
screw into the center hole. Tighten all three
screws 2 – 3 turns each, finger-tight only (1).
5. Using the torque wrench and 7/16" socket,
tighten each outer screw between 5.0 and
10 in-lbs (2).
6. Using the torque wrench and 9/64" allen
head socket, tighten the center screw
between 12 and 18 in-lbs (3).
7. Now tighten the two outer screws between
30 and 40 in-lbs (4).
8. Replace the Power Module PC board as
described above.
F-69