GMC T Series 1994 Repair Manual page 608

Figure 7— Slip Ring End Frame with Stator
Removed
CLEANING AND INSPECTIO N
All metal parts except the voltage regulator, rectifier
bridge, stator, rotor, and bearing assemblies in a
suitable solvent.
— Wipe or blow the parts dry.
I?
Inspect
1. Brush holder for damage.
P y | Clean
• Brush holder. Make sure the brush pockets are
clean.
• Brushes with a soft dry cloth.
2. Brushes for wear. If the brushes are worn to 11 mm
(0.4 inch) or less in length, replace the brush hold­
er assembly. Use a retainer pin to hold the brushes
in the holders.
3. Brush springs for broken wire or corrosion.
4. Slip ring end of the rotor shaft for overheating or
scoring. If signs of overheating or scoring are pre­
sent, replace the rotor. The slip ring end bearing
must be replaced any time the two halves of the
generator are separated.
INSPECTION AND REPAIR
5. Drive end bearing for roughness, looseness, or
wear. If the condition of the bearing is doubtful,
replace it.
6. Windings for burned insulation. Replace the rotor
or stator if either looks burned.
• Burned insulation appears as very dark or
blackened wiring. A strong acidic odor will be
apparent.
7. Terminal connectors for corrosion or breaks.
8. Windings on the stator for chipped insulation. If the
chipped area is small and the rest of the stator is
OK, repair the stator with insulating varnish.
9. Slip rings for scoring, wear, or pitting.
A. If the rings are dirty, clean with a 400 grain or
finer polishing cloth.
B. Spin the rotor and hold the polishing cloth
against the slip rings until they are clean.
C. If scored, worn, or pitted, true the rings in a
lathe to 0.05 mm (0.002 inch).
D. Finish with 400 grain or finer polishing cloth.
Blow away all dust.
10. Rotor and stator windings electrically as described
under " Electrical Tests" .
11. Generator housing for cracks, warping, or other
damage.
12. If the regulator, brush assembly, or connector
needs replacing, it will have to be unsoldered from
the other two components. Use as little heat as
possible to protect the regulator (figure 9).