Brush And Slip Ring Service Procedure - Lincoln Electric Fleet 400 Service Manual

LINCOLN ELECTRIC

BRUSH AND SLIP RING SERVICE 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 provides guidance in testing and maintaining the Brush and Slip Ring system.
MATERIALS NEEDED
Volt/Ohmmeter
500 or 600 Grit Sand Paper
180 Grit Sand Paper
Low Pressure Compressed Air
Wiring Diagram
TEST PROCEDURE
1. Turn off the engine on the Fleet 400 machine.
2. Perform the Case Cover Removal Procedure.
3. Perform the Chopper Module Capacitor Discharge Procedure.
4. Remove the brush holder bracket.
5. Examine brushes and slip rings. The slip rings, brush holder and brushes should be clean and free
from oil or grease. The brushes should be making good, continuous contact with the slip rings.
6. The brushes should be of sufficient length and have adequate spring tension. Generally, the
brushes should be replaced if either brush has less than 1/4" remaining before it reaches the end of
its travel. Spring tension should be sufficient to hold the brushes firmly against the slip rings.
7. The brushes should be removed from the brush holder and examined. The terminals should be
clean.
8. If the slip rings are discolored, display evidence of excessive sparking or the brushes have worn
prematurely. These may be signs of a grounded or a shorted rotor. Perform the Rotor Resistance
and Ground Test Procedures (Static) and (Dynamic).
9. 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 intermittent
instability or loss of both weld and auxiliary output. If there is any evidence that the brushes may
have been sticking in the brush holders, a new brush holder and brush assembly should be installed.
CLEANING SLIP RINGS:
10. In the event that the slip rings have become dirty, discolored or mildly pitted, it will be necessary to
clean them, using very fine, 500 or 600 grit sand paper.
Fleet™ 400 Service Manual
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