Exciter Brush And Slip Ring Service Procedure - Lincoln Electric Classic 300 MP Service Manual

LINCOLN ELECTRIC

EXCITER BRUSH AND SLIP RING SERVICE PROCEDURE

(Exciter / Auxiliary Power Alternator)
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 provides guidance in testing and maintaining the Brush and Slip Ring System of the Exciter /
Auxiliary Power Alternator.
MATERIALS NEEDED
5/16" Nutdriver
Very Fine Grit Emory Cloth
180 Grit Sandpaper
TEST PROCEDURE
1. Turn off the engine on the Classic 300 MP machine.
2. Using a 5/16" nutdriver, remove the four screws securing the exciter cover to the machine. See
Figure F.19.
3. Examine brushes, slip rings and brush holder. See Figure F.20.
• Brushes should be clean and free from oil or grease.
• Brushes should be of sufficient length and have adequate spring tension.
• Brushes should be making good, continuous contact with the slip rings and should be riding near the
center of the slip rings. (The brush holder bracket may need to be slightly bent to achieve acceptable
alignment.)
(Generally, the brushes should be replaced if either brush has less than 1/4" remaining before it reaches
the end of its travel.)
4. If the slip rings are very dark in color, display evidence of excessive arcing or have worn
prematurely, these may be signs of a grounded or shorted rotor. Perform the Test Procedure.
5. Check for evidence of sticking brushes. Sticking brushes will normally result in the slip rings being
pitted and discolored from excessive arcing. Another sign of sticking brushes is instability or loss of
both weld and auxiliary output, but the machine may begin to work properly, for a short time, after
being jarred or moved.
6. If there is any evidence that the brushes may have been sticking in the brush holders, a new brush
and brush holder assembly should be installed.
Classic® 300 MP Service Manual
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