ALTERNATOR TROUBLESHOOTING - TM-10-3930-638-24-P0595

TM 10-3930-638-24&P

3-9.

ALTERNATOR

TROUBLESHOOTING

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

1. IMPROPER OUTPUT VOLTAGE

Step 1.

Connect test set-up to alternator as illustrated.

Slowly increase alternator speed and observe voltmeter

reading.

a. If voltmeter reading is uncontrolled with speed, and

increases above 31 Vdc, check alternator field wind-

ing and regulator (para 3-12).

b. If voltmeter indicates battery voltage (no increase

in voltage), proceed to step 2.

c. If voltmeter reading increases (greater than battery

voltage and less than 31 Vdc), proceed to MAL-

FUNCTION 2 (IMPROPER OUTPUT CURRENT).

Step 2.

CAUTION

Tab is within 3/4 inch of casting surface. Do not force screwdriv-

er deeper than one inch into alternator end frame.

Insert screwdriver into test hole in end frame and ground

tab as shown; then repeat step 1.

a. If voltmeter indicates battery voltage (no increase

in voltage), check rotor, stator, diode trio, rectifier

bridge, and regulator mounting screws (para 3-12).

b. If voltmeter reading increases, replace the regulator