Generator Inspection

Using a vernier caliper, measure the brush length.

Standard length:

9.5 to 11.5 mm (0.374 to 0.453 in.)

Minimum length:

4.5 mm (0.177 in.)

Check the resistance.

1. Measure the resistance between the slip rings.
   

   Standard resistance:

   2.3 to 2.7 Ω at 20°C (68°F)
   

   If the result is not as specified, replace the generator rotor assembly.
   




2. Measure the resistance between the slip ring and rotor core.
   

   Standard resistance:

   1 MΩ or higher
   

   If the result is not as specified, replace the generator rotor assembly.
   

Check the slip ring diameter.

1. 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 mm (0.551 in.)
   

   If the diameter is less than the minimum, replace the generator rotor assembly.
   

Check the appearance.

1. Check that the bearing is not rough or worn.
   

   OK:

   The bearing rotates smoothly.
   

   If the result is not as specified, replace the generator rotor assembly.
   

Check that the bearing is not rough or worn.

OK:

The bearing rotates smoothly.