Alternator: Testing and Inspection

ROTOR
1. Measure the resistance between the slip rings by using an ohmmeter.

Specification: 2.4-2.9 ohms @ 2O°C (68°F)

- If it is not within the specification, replace the rotor.

2. Check continuity between the slip ring and the core by using an ohmmeter. Replace the rotor if there is continuity.




3. If the slip ring surface is rough, use a lathe or fine sandpaper to repair it.




STATOR
1. Wiring damage
a. Check for continuity between the stator coil leads by using an ohmmeter.
b. Replace the stator if there is no continuity.




2. Ground of stator coil
a. Check continuity between the stator coil leads and the core by using a circuit tester.
b. Replace the stator if there is continuity.




BRUSHES
If any brush is worn almost to or beyond the limit, replace all of the brushes.

Standard: 21.5 mm (0.846 in)
Minimum: 8.0 mm (0.315 in)





BRUSH SPRINGS
1. Measure the force of the brush spring by using a spring pressure gauge. Read the spring pressure gauge at the brush tip projection of 2 mm (0.079 in).
2. Replace the spring if necessary.

Standard force: 3.2-4.3 N (0.71-0.96 lbs.)
Minimum: 1.8 N (0.4 lbs.)





RECTIFIER
1. Check continuity of the diodes by using an ohmmeter.




2. Replace the rectifier if not as specified.




BEARINGS
1. Check for abnormal noise, looseness, and sticking.
2. Replace if necessary.