Armature Test
- Use DVOM to check continuity between 2 side-by-side commutator bars. Check each segment same way. If continuity is not present, replace armature. Check for continuity between each commutator bar and armature shaft. If continuity exists, replace armature.
- If commutator surface is rough, sand lightly using No. 500 or 600 grit sandpaper. Using a micrometer or vernier caliper, measure commutator diameter. If commutator diameter is not within specification, replace armature. See MINIMUM COMMUTATOR DIAMETER table.
- Check depth of insulating mold between commutator bars. If depth is less than .008" (.2 mm), undercut to .020-.031" (.5-.8 mm) using a hacksaw blade.
MINIMUM COMMUTATOR DIAMETER
| Application | In. (mm) | |
|---|---|---|
| G20 | ||
| Hitachi | 1.3 (32) | |
| Mitsubishi | 1.1 (29) | |
| M30 | ||
| Hitachi | 1.3 (32) | |
| Mitsubishi | 1.5 (38) | |
| Q45 | 1.1 (29) | |