Lincoln Electric SAE-300 HE Service Manual page 32

LINCOLN ELECTRIC SAE-300® HE Service Manual
6. 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:
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) emery cloth or a 220 or 320 grit commutator stone.
Commutator stones should only be used by experienced technicians who have the knowledge and
equipment necessary to use them safely.
Seating brushes:
If brushes have been replaced, repositioned, or are not making full contact with the slip rings, it will
be necessary to re-seat them. This can be done by placing a strip of 180 grit sandpaper between the
slip rings and the brushes, with the abrasive side against the brushes. Pull the sandpaper strip
around the circumference of the slip rings in the direction of rotor rotation only. Repeat this
procedure until the surface of each brush is in full contact with its matching slip ring.
Use low pressure compressed air to thoroughly blow the carbon, commutator stone and sandpaper
dust from the machine before operating.
Securely connect the leads to the brush terminals (See Wiring Diagram) and replace the alternator
cover if testing and service is complete.
Figure F.7 – Brush locations
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