Alternator: Testing and Inspection
INSPECTION1. INSPECT GENERATOR ROTOR ASSEMBLY
a. Check the rotor for an open circuit.
1. Measure the resistance between the slip rings.
Standard resistance: 2.3 to 2.7 kOhms at 20 degrees C (68 degrees F)
If the result is not as specified, replace the rotor assembly.
b. Check if the rotor is grounded.
1. Measure the resistance between the slip ring and rotor.
Standard resistance: 10 kOhms or higher
If the result is not as specified, replace the rotor assembly.
c. Check that the slip rings are not rough or scored.
If rough or scored, replace the rotor assembly.
d. Using a vernier caliper, 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 assembly.
2. INSPECT GENERATOR BRUSH HOLDER ASSEMBLY
a. Using a vernier caliper, measure the exposed brush length.
Standard exposed length: 10.5 mm (0.413 in.)
Minimum exposed length: 4.5 mm (0.177 in.)
If the exposed length is less than the minimum, replace the brush holder assembly.
3. INSPECT GENERATOR DRIVE END FRAME BEARING
a. Check that the bearing is not rough or worn.
If necessary, replace the bearing.
4. INSPECT GENERATOR ROTOR BEARING
a. Check that the bearing is not rough or worn.
If necessary, replace the generator rotor.