- Use a circuit tester to measure the armature for grounding.
If the circuit tester indicates continuity, the armature is grounded, replace the armature assembly.
- Hold one probe of the circuit tester against the commutator segment.
- Hold the other circuit tester probe against the armature shaft.
- Measure the armature and commutator run-out. If the measurement is out of limit, correct the commutator and/or replace the armature assembly.
Armature run-out:
Standard:
0.05 mm (0.0020 in.) max.
Limit:
0.1 mm (0.0039 in.)
Commutator run-out:
Standard:
0.05 mm (0.0020 in.) max.
Limit:
0.1 mm (0.0039 in.)
- If there is rough surface on the commutator, use sand paper number 500 to 600 for correction.
- Inspect the commutator mica segment for excessive wear. If the mica segment depth is less than the limit, replace the commutator. Measure the mica segment depth.
Mica segment depth:
Standard:
0.5 – 0.8 mm (0.0197 – 0.0315 in.)
Limit:
0.2 mm (0.0079 in.)
