CAUTION
Never use a mega tester (measuring use for high voltage) or any other similar devise for this test; otherwise, the diodes may be damaged.
| Diode test
|
- Check the positive diode continuity in the direction from the diode lead to the positive side heat sink
- Resistance specification: 1 Ohm or less
- Check the negative diode continuity in the direction from the negative side heat sink to the diode lead
- Resistance specification: 1 Ohm or less
| Rotor slip ring test
|
- Inspect the slip rings for roughness or any contamination of the surface. Repair the slip ring surface using a lathe or sand paper
- Measure the slip ring outer diameter and replace rotor assembly if under spec.
- O.D. Specification: Standard 22.7 mm (0.894 in) Limit 22.1 mm (0.870 in)
- Using a digital multi-meter, check resistance between the slip rings and replace rotor assembly if not within spec.
- Resistance specification: Approx. 1.8 - 2.2 Ohm
| Rotor insulation test
|
- Check the continuity between slip ring and rotor core or shaft and replace if not in spec.
- Resistance specification: 1 Ohm or less
- Check the rear ball bearing and replace if it is noisy or if the rotor does not turn smoothly
| Stator test
|
- Using a digital multi-meter, check resistance of the stator between each end of the lead wires and replace ass. if excessive resistance is present
- Resistance specification 1 MOhm or less
- Using a digital multi-meter, resistance check the stator coil for continuity between the stator core and each end of lead wire and replace if out of spec.
- Resistance specification: 1 Ohm . or more
| Brush length check
|
- Measure each brush for length and replace if not within spec.
- Specification at service limit mark (A). Brush length: Standard 18.5 mm (0.728 in) Service limit 5.0 mm (0.197 in)
| Brush spring pressure test
|
- Using a spring pressure indicator, push the brush into brush holder until its tip protrudes 2 mm (0.08 in) then measure the pressure of brush spring and replace if out of spec.
- Pressure specification: no less than 2.2 N (224 g, 7.91 oz). ; new spring pressure spec. is 4.8 to 6.0 N (489 to 612 g, 17.26 to 21.60 oz)
- Check the front ball bearing for resistance while rotating. If resistance is felt or abnormal noise is heard, replace same
