TM-9-2320-280-34

TRUCK, UTILITY: M998 SERIES

TECHNICAL MANUAL; DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE

JANUARY 1996

TM-9-2320-280-34 - Page 322 of 1258

6 - 3 . 2 . 100 AMPERE ALT E R N ATOR (12342944) TESTING AND REPAIR (Cont’d)

Table 6-A. No-Load Test.

AMPS

VOLTS

DIAGNOSIS

High

Low

Test bench battery is discharged (or defective).

Allow to charge (or replace).

High

Normal

Give time to stabilize while monitoring VOLTS.

If VOLTS rise above normal range (26-30 volts),

regulator and/or tube assembly must be replaced.

If AMPS fall, charging system is OK.

High

High

STOP TEST. Regulator and/or tube assembly must

be replaced. Refer to Static Te s t i n g

.

Low

Low

Alternator and/or regulator must be repaired or

replaced. Refer to table 6-A.2.

Low

Normal

Regulator OK. Refer to table 6-A.1.

Low

High

STOP TEST.

Bench malfunction or wiring error.

TM 9-2320-280-34

Change 1

6 - 1 8 . 1 7

6.

Perform no-load test. Set test stand battery circuit selector to 24 VDC, IGN switch to ON, and start

varidrive. Observing the DC voltmeter output voltage and tachometer rpm, increase speed until

tachometer reads 5000 rpm. Record voltmeter reading and refer to table 6-A for diagnosis.