HDB Series and M1 Series Heavy Duty Brushless Alternators Caterpillar

Field Winding Continuity Test

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Illustration 1	g00825532
Field Winding Continuity Test (6) Field winding leads

1. Remove the rear cover.

2. If the alternator has a capacitor, remove the capacitor.

3. Remove the regulator.

4. Connect the multimeter leads across field winding leads (6). This is shown in Illustration 1.

5. Measure the resistance between the field winding leads.

   Expected Results:

   M1 Series Alternators ... 9 ± 0.1 ohms

   HDB Series Alternators ... 8.2 ± 0.4 ohms

   Results:

   OK - The resistance is within tolerance. The field winding is normal. STOP.

   NOT OK - The resistance is above tolerance. The field winding has an open circuit. Replace the field winding. STOP.

   NOT OK - The resistance is below tolerance. The field winding has a short circuit. Replace the field winding. STOP.

Field Winding Ground Test

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Illustration 2	g00825533
Field Winding Ground Test (6) Field winding leads (7) Rear frame

1. The rear cover, the capacitor, and the regulator remain removed from the alternator.

2. Connect the multimeter leads across rear frame (7) and one field winding lead (6). This is shown in Illustration 2.

3. Measure the resistance.

   Expected Result: The resistance is greater than 100000 ohms.

   Results:

   OK - The resistance is greater than 100000 ohms. Repeat steps 1 to 3 for the other field winding lead (6). If all of the results are OK, the stator is normal. STOP.

   NOT OK - The resistance is NOT greater than 100000 ohms. The field winding lead is shorted to the frame. Replace the field winding. STOP.