Charging System - Generators & Regulators: Generator: Inspection

1. Using an ohmmeter, check the continuity between terminals F and B.
   Fig 1: Using Ohmmeter To Check Continuity Between Terminals F & B

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   1. Standard: 
   2. When the positive and negative poles between terminals F and B are exchanged, there is continuity in one direction, but not in the other. 

   If the continuity is not as specified, replace the voltage regulator.

2. Using an ohmmeter, check the continuity between terminals F and E.
   Fig 2: Checking Continuity Between Terminals F & E

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   1. Standard: 
   2. When the positive and negative poles between terminals F and B are exchanged, there is continuity in one direction, but not in the other. 

   If the continuity is not as specified, replace the voltage regulator.

Using an ohmmeter, check that there is continuity between the slip rings.

Fig 3: Checking Continuity Between Slip Rings

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Standard resistance: 2.1 - 2.5 Ohms at 20° C (68°F) 

If there is no continuity, replace the rotor.

Fig 4: Inspecting For Grounded Rotor

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Using an ohmmeter, check that there is no continuity between the slip ring and rotor.

If there is continuity, replace the rotor.

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.
   Fig 5: Measuring Slip Ring Diameter

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   Standard diameter: 14.2 - 14.4 mm (0.559 - 0.567 in.) 

   Minimum diameter: 12.8 mm (0.504 in.) 

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

Using an ohmmeter, check that there is continuity between the coil leads.

If there is no continuity, replace the drive end frame assembly.

Fig 6: Checking Stator For Continuity

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Fig 7: Checking Stator For Ground

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Using an ohmmeter, check that there is no continuity between the coil lead and drive end frame.

If there is continuity, replace the drive end frame assembly.

Using vernier calipers, measure the exposed brush length.

Fig 8: Using Vernier Calipers To Measure Exposed Brush Length

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Standard exposed length: 10.5 mm (0.413 in.) 

Minimum exposed length: 1.5 mm (0.059 in.) 

If the exposed length is less than minimum, replace the brush holder.

Fig 9: Using Ohmmeter To Inspect Rectifier
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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 step  a.
3. Check that one shows continuity and the other shows no continuity.

   If continuity is not as specified, replace the rectifier holder.

1. Using an ohmmeter, connect one tester probe to each negative (-) terminal and the other to each rectifier terminal.
   Fig 10: Using Ohmmeter To Inspect Negative Rectifier

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2. Reverse the polarity of the tester probes and repeat step  a.
3. Check that one shows continuity and the other shows no continuity.

   If continuity is not as specified, replace the rectifier holder.

Check that the bearing is not rough or worn.

If necessary, replace the bearing.