Alternator: Testing and Inspection
INSPECTION1. INSPECT GENERATOR BRUSH HOLDER ASSEMBLY
a. Using vernier calipers, measure the exposed brush length.
Standard exposed brush length: 10.5 mm (0.413 in.)
Minimum exposed brush length: 4.5 mm (0.177 in.)
If the exposed brush length is less than the minimum, replace the brush holder.
2. INSPECT GENERATOR ROTOR ASSEMBLY
a. Check the rotor for an open circuit.
1. Using an ohmmeter, measure the resistance between the slip rings.
Standard: 2.3 to 2.7 Ohms at 20°C (68°F)
If the result is not as specified, replace the rotor.
b. Check the rotor for ground.
1. Using an ohmmeter, measure the resistance between the slip ring and rotor.
Standard: 10 k Ohms or higher
If the result is not as specified, replace the rotor.
c. Inspect the slip rings.
1. Check that the slip rings are not rough or scored. If rough or scored, replace the rotor.
2. Using vernier calipers, measure the slip ring diameter.
Standard diameter: 14.2 to 14.4 mm (0.559 to 0.567 in.)
Minimum diameter: 14.0 mm (0.551 in.)
If the diameter is less than the minimum, replace the rotor.
3. INSPECT GENERATOR ROTOR BEARING
a. Check the bearing whether it is rough or worn. If necessary, replace the generator rotor.