Lincoln Electric SAE-300 HE, Service Manual, Page: 31 / 84

LINCOLN ELECTRIC SAE-300® HE Service Manual
26
Test Procedures
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
500 Or 600 Grit Emery Cloth
180 Grit Sandpaper
220 Or 320 Grit Commutator Stone (Optional)
TEST PROCEDURE
1. Turn off the engine on the SAE-300 HE machine.
2. Remove the covers from the exciter / auxiliary power alternator by removing the screws securing it.
3. Examine brushes, slip rings and brush holder. See Figure F.7 .
• Brushes should be clean and free from oil or grease.
• The 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 Exciter Rotor
Resistance and Ground Test Procedure (Exciter / Auxiliary Power Alternator) .
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.