HDB Series and M1 Series Heavy Duty Brushless Alternators Caterpillar

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Illustration 1	g00825472
(1) Capacitor (2) Wire assembly

1. Remove the rear cover.

2. Disconnect wire assembly (2) from the back of the rectifier.

3. Touch wire assembly (2) to one of the capacitor mounting screws in order to discharge the capacitor.

4. Remove capacitor (1) .

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Illustration 2	g00825475
Capacitor Test (3) Terminal (4) Terminal

5. Connect the multimeter leads across terminal (3) and terminal (4) of the capacitor.

6. Measure the resistance between the terminals.

   Expected Result: The resistance is low for a short period of time. The resistance stabilizes above 100000 ohms.

   Results:

   OK - The resistance stabilizes above 100000 ohms. The capacitor is normal. Repeat step 3. STOP.

   NOT OK - The resistance does NOT stabilize above 100000 ohms. The capacitor has failed. Replace the capacitor. STOP.

Series Resistor Test

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Illustration 3	g00825479
Series Resistor Test (3) Terminal (5) Terminal

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

2. Connect the multimeter leads across terminal (3) and terminal (5) of the capacitor.

3. Measure the resistance between the terminals.

   Expected Result: The resistance is 990 to 1210 ohms.

   Results:

   OK - The resistance is 990 to 1210 ohms. The series resistor is normal. STOP.

   NOT OK - The resistance is NOT 990 to 1210 ohms. The series resistor has failed. Replace the capacitor. STOP.