Component Tests and General Diagnostics

ROTOR




Open Circuit
Using ohmmeter, check for continuity between slip rings of rotor. If there is no continuity, replace rotor.

Standard resistance: About 2.9 Ohms.




Ground
Using ohmmeter, check that there is no continuity between slip ring and rotor. If there is continuity, replace rotor.




Slip Rings
- Check slip rings for roughness or scoring. If rough or scored, replace rotor.
- Using a vernier caliper, measure the slip ring diameter.

Standard diameter: 14.4 mm (0.567 in.)
Minimum diameter: 14.0 mm (0.551 in.)

If the diameter is less than minimum, replace the rotor.

STATOR




Open Circuit
Using ohmmeter, check all leads for continuity. If there is no continuity, replace stator.




Ground
Using ohmmeter, check that there is no continuity between coil leads and stator core. If there is continuity, replace stator.




Brush and brush holder
Check each brush for wear by measuring its length.

[Type A]
If brush is found worn down to service limit, replace brush.

[Type B]
If brush is found worn down to service limit, replace brush and brush
holder.

Exposed brush length "a"
Standard: 10.5 mm (0.413 in.)
Limit : 4.5 mm (0.351 in.)

RECTIFIER




Positive Rectifier
1. Using an ohmmeter, connect one tester probe to the B terminal and the other to each rectifier terminal.
2. Reverse the polarity of the tester probes and repeat step 1.
3. Check that one shows continuity and the other shows no continuity.
If there is continuity, replace the rectifier holder.




Negative Rectifier
1. Using an ohmmeter, connect one tester probe to each negative terminal and the other to each rectifier terminal.
2. Reverse the polarity of the tester probes and repeat step 1.
3. Check that one shows continuity and the other shows no continuity.
If there is continuity, replace the rectifier holder.

BEARING




Drive End Bearing
Check that the bearing is not rough or worn.




End Housing Bearing
Check that the bearing is not rough or worn.