Troubleshooting & repair, Diode removal and replacement (continued) – Lincoln Electric COMMANDER SVM145-B User Manual
Page 150
TROUBLESHOOTING & REPAIR
F-94
F-94
COMMANDER 300
DIODE REMOVAL AND REPLACEMENT
(continued)
TEST PROCEDURE
1.
Turn the engine off.
2.
Perform the Output Panel Removal
Procedure.
3.
Perform the Capacitor Discharge
Procedure.
4.
Using the 7/16" wrench, remove the appro-
priate stator leads and diode pigtail lead from
the stud on the output rectifier bridge plastic
insulator bracket. Label leads for reassembly
if more than one is removed. See Figure
F.43.
5.
Using the 1" wrench, loosen the appropriate
diode and remove the diode that is to be
replaced.
6.
Clean the area on the heat sink around the
diode mounting surface using a putty knife or
similar tool. DO NOT SCRATCH THE
DIODE MOUNTING SURFACE.
7.
Polish the heat sink's mounting surface using
an abrasive disc, E2827-2 to provide a bright,
clean surface where the diode seats on the
heat sink. Wipe the surface clean with a lint-
free cloth or paper towel.
8.
Inspect the mounting surfaces of each new
diode. Remove all burrs and wipe clean. Do
not use steel wool or any abrasive cleanser
on the diode mounting surface.
9.
Apply a thin (0.003" to 0.007") uniform layer
of Penetrox A13 joint compound to the heat
sink mounting surface.
10.
Do not apply compound to the diode stud or
mounting threads.
11.
Apply two drops of Loctite 271to the diode
stud threads before tightening.
NOTE: The diode threads must be clean and free
of defects so that it can be finger tightened before
applying torque. A “slip” type torque wrench must
be used to tighten the diode.
12.
Tighten the diode to the specifications in the
following table.
DIODE
FOOT-POUNDS
INCH-POUNDS
SIZE
3/4 - 16
25-27
300-324
3/8 - 24
10±.5
125+0/-5
13.
Connect the stator leads and diode pigtail
leads as labeled at disassembly.
14.
Replace the output panel.
FIGURE F.43 – POWER MODULE/OUTPUT RECTIFIER BRIDGE ASSEMBLY DETAILS
HEATSINKS
DIODE
PIGTAIL
LEADS
DIODE