Lincoln Electric Classic 300 MP Service Manual page 22

LINCOLN ELECTRIC
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
The welding output varies
abnormally. The auxiliary
output remains constant. The
engine is operating properly.
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.
POSSIBLE AREAS OF
MISADJUSTMENT(S)
OUTPUT PROBLEMS
1. Check for loose, worn, dirty
or poorly seated DC generator
brushes.
2. The armature commutator
may need cleaned.
3. Check for loose or faulty
welding cables.
Classic® 300 MP Service Manual
TROUBLESHOOTING GUIDE
RECOMMENDED
COURSE OF ACTION
1. Perform the Shunt Field Coil
Resistance And Ground Test
Procedure.
2. Perform the Output Choke
Test Procedure.
3. Perform the Selector Switch
Test Procedure.
4. Perform the Shunt Field
Circuit Voltage Test Procedure.
5. Perform the Rocker
Adjustment Procedure.
6. Perform the Welding
Generator Brush And
Commutator Inspection And
Service.
7. Perform the Weld Circuit
Ground And Short Circuit Test
Procedure.
8. While the machine is loaded,
check the interpole and series
coils for signs of "arcing". This
condition would point to
shorted turns in the "arcing"
coil.
9. The main armature may be
faulty. Check for grounds.
10. Perform the Control Board
Test Procedure.
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