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WELDING GENERATOR BRUSH AND COMMUTATOR
INSPECTION AND SERVICE PROCEDURE (continued)
PROCEDURE
1. Shut off the engine.
2. Open either, or both of the side doors of the
Classic® 300 machine.
NOTE: Secure the doors in the open position using
the door restraint system. If the machine
does not have a door restraint system,
remove the doors or securely restrain them
to prevent them from falling closed.
3. Disconnect the negative battery cable.
4. Remove the cover protecting the welder gener-
ator brushes.
Examine the Commutator:
Normal appearance:
The commutator should appear smooth, and have
an even brown color where the brushes ride.
Blackened Commutator:
A commutator that appears an even black color all
around may indicate a grounded armature, shorted
weld circuit, a serious overload condition, or out-of-
adjustment rocker. It could also indicate the use of
poor quality brushes, or brushes that have been
contaminated with oil or some other foreign sub-
stance.
• Check the rocker position. Be certain that it is
aligned with or very close to the factory drill
mark. See Figure F.3. IMPORTANT: If the rocker
position requires adjustment, do not over tighten
the rocker clamping screw. This screw should be
tightened to a torque of 70 to 75 Inch-Lbs. Over
tightening can destroy the rocker.
• Perform the Weld Circuit Ground and Short
Circuit Test.
• If the weld circuit is not grounded or shorted, and
poor brush quality or contamination is suspect-
ed, replace the brushes and seat them with a
commutator stone or sand paper.
• If brush quality or contamination is not suspect-
ed, clean the commutator by lightly stoning the
surface. See caution note on commutator stone
use.
TROUBLESHOOTING AND REPAIR
F-54 F-54
CLASSIC® 300D & 300G
FIGURE F.3 - DRILL MARK LOCATIONS
ROCKER
DRILL MARKS
EXCITER BRACKET
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