GENERAL TEST PROCEDURES

TM 9-2920-257-30&P

2-6. GENERAL TEST PROCEDURES

CAUTION

If voltmeter reading exceeds 30.5 volts for 24 volt systems, STOP engine

immediately and refer to Table 2-3.

a. Start engine and accelerate to high idle.

Refer to TM 9-2350- 261-10, or TM 9-2350-277-10, or

TM 9-2350-247-10 Operator TM's.

b. Observe ammeter and voltmeter readings on multimeter. If battery is sufficiently discharged, amps should be

"high" within +1- 10% of output specified by performance curve (generator RPM = engine idle RPM X pulley ratio). Volts

should be within or below the "normal range" of Table 2-2. As battery approaches full charge, amps should fall as volts

rise. When amps and volts stabilize, note readings and refer to Table 2-3.

Table 2-3. TROUBLESHOOTING DIAGNOSIS

AMPS

VOLTS

DIAGNOSIS

CHARGING SYSTEM GOOD. BATTERY NOT FULLY

CHARGED. WAIT FOR CHARGING SYSTEM TO BRING

HIGH

LOW

BATTERY TO FULL CHARGE. AMPS SHOULD FALL

AND VOLTS SHOULD STABILIZE WITHIN NORMAL

RANGE PER TABLE 2-2.

NOTE IF AMPS FALL OR VOLTS EXCEED NORMAL

RANGE PER TABLE 2-2. IF AMPS FALL AND VOLTS

HIGH

NORMAL

REMAIN NORMAL, CHARGING SYSTEM IS GOOD. IF

VOLTS EXCEED NORMAL, REGULATOR AND/OR FIELD

COIL SHOULD BE REPLACED. GO TO STATIC TESTS.

STOP TEST. REGULATOR AND /OR FIELD COIL

HIGH

SHOULD BE REPLACED. GO TO STATIC TESTS.

IF BOTH AMPS AND VOLTS ARE LOW, CHECK TO BE

SURE MULTIMETER LEADS ARE PROPERLY

LOW

ATTACHED. IF OKAY, REPLACE EITHER GENERATOR

OR REGULATOR. REFER TO GENERATOR AND

REGULATOR TEST PROCEDURE.

LOW

NORMAL

CHARGING SYSTEM GOOD.

STOP TEST. IF BATTERY AND VOLTMETER ARE BOTH

LOW

HIGH

GOOD, REPLACE REGULATOR AND/OR FIELD COIL.

c. Discover the cause for failure then disassemble and repair the generator before proceeding with prescribed tests.

Performing additional operational tests on a damaged generator will only increase the damage.

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