Generator Inspection

Check the rotor for an open circuit.

1. Measure the resistance between the slip rings.
   

   Standard resistance:

   2.7 to 3.1 Ω at 20°C (68°F)
   

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

Check the rotor for a short circuit.

1. Measure the resistance between each slip ring and the rotor.
   

   Standard resistance:

   10 kΩ or higher
   

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

Check that the slip rings are not rough or scored.
If they are rough or scored, replace the rotor.

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:

12.8 mm (0.504 in.)

Inspect the bearing.

1. Check that the bearing is not rough or worn.
   If necessary, replace the generator rotor.
   

Check the stator for an open circuit.

1. Measure the resistance between the coil leads.
   

   Standard resistance:

   Below 1 Ω
   

   If the result is not as specified, replace the drive end frame assembly.
   

Check the stator for a short circuit.

1. Measure the resistance between each coil lead and the drive end frame assembly.
   

   Standard resistance:

   10 kΩ or higher
   

   If the result is not as specified, replace the drive end frame assembly.
   

Inspect the bearing.

1. Check that the bearing is not rough or worn.
   If necessary, replace the drive end frame assembly.
   

Using a vernier caliper, measure the exposed brush length.

Standard exposed length:

9.5 to 11.5 mm (0.374 to 0.453 in.)

Minimum exposed length:

1.5 mm (0.059 in.)

Check the positive terminal of the rectifier.

1. Using an ohmmeter, connect one tester probe to the positive (+) terminal and the other to each rectifier terminal.
   

2. Reverse the polarity of the tester probes and repeat the step above.
   

3. Check that one shows a resistance of below 1 Ω and the other shows a resistance of 10 kΩor higher.
   If the result is not as specified, replace the generator holder with rectifier.
   

Check the negative terminal of the rectifier.

1. Using an ohmmeter, connect one tester probe to each negative (-) terminal and the other to each rectifier terminal.
   

2. Reverse the polarity of the tester probes and repeat the step above.
   

3. Check that one shows a resistance of below 1 Ω and the other shows a resistance of 10 kΩor higher.
   Check that there is a resistance of 10 kΩor higher.
   If the result is not as specified, replace the generator holder with rectifier.
   

Using an ohmmeter, measure the resistance between terminals F and B.

Standard resistance:

Below 1 Ω or 10 kΩ or higher

HINT:

When the ohmmeter's leads are initially touched to the regulator, one of the above values will be output. When the leads are reversed, the reading will change to the other value.

Using an ohmmeter, measure the resistance between terminals F and E.

Standard resistance:

Below 1 Ω or 10 kΩ or higher

HINT:

When the ohmmeter's leads are initially touched to the regulator, one of the above values will be output. When the leads are reversed, the reading will change to the other value.