Exciter Field Diode Removal And Replacement Procedure - Lincoln Electric Classic 300 MP Service Manual

LINCOLN ELECTRIC

EXCITER FIELD DIODE REMOVAL AND REPLACEMENT PROCEDURE

Service and repair should be performed by only Lincoln Electric factory trained personnel. Unauthorized
repairs performed on this equipment may result in danger to the technician or machine operator and will
invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety
notes and precautions detailed throughout this manual. If for any reason you do not understand the test
procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department
for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
TEST DESCRIPTION
This procedure will aid the technician in the removal and replacement of the Exciter Field Diode.
MATERIALS NEEDED
3/8" Nutdriver
11/32" Nutdriver
Dow Corning 340 Heat Sink Compound (Lincoln Part #T12837)
Wiring Diagram
REMOVAL PROCEDURE
1. Turn off the engine on the Classic 300 MP machine.
2. Using a 3/8" nutdriver, remove the two screws securing the finger guard panel to the machine. See
Figure F.51.
3. Label and disconnect leads 610, 610A, 602C, 600, 600C, and 21 from the exciter field diode
terminals. See
4. Using an 11/32" nutdriver, remove the nut, lock washer and flat washer securing the exciter field
diode to the machine. See
5. The exciter field diode can now be removed.
REPLACEMENT PROCEDURE
1. Clean the mounting surface and apply a coating of Dow Corning 340 heat sink compound to the rear
of the mating surface of the exciter field diode.
2. Carefully position the new exciter field diode onto its mounting stud.
3. Using a 11/32" nutdriver, attach the nut, lock washer and flat washer securing the exciter field
diode to the machine.
4. Connect leads 610, 610A, 602C, 600, 600C, and 21 to the exciter field diode
Diagram.
5. Using a 3/8" nutdriver, attach the two screws securing the finger guard panel to the machine.
6. Perform the Retest After Repair Procedure.
Figure F.52. See Wiring Diagram.
Figure F.53.
Classic® 300 MP Service Manual
terminals. See Wiring
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