TESTING - TM-9-2320-285-24-20048

TM 9-2320-285-24-2

3-9. ALTERNATOR MAINTENANCE (CONT)

STEP

LOCATION

ITEM

ACTION

REMARKS

TESTING

Field coil (21) Test

Using ohmmeter check:

a. For grounds. Connect ohmmeter between one field

coil lead and housing (sequence A as shown).

Field coil is grounded if reading is low

b. For opens. Connect ohmmeter between two field

coil leads (sequence B as shown). Field coil is

open if ohmmeter reading is high or infinite

c. For short circuits. Connect ohmmeter between two

field coil leads (sequence B as shown).

Winding is shorted if ohmmeter reading is less

than 0.2 ohms. Replace field coil if defective

Using ohmmeter connect prod

to grounded heat sink and base of

one of the three terminals as

shown.

Observe

reading.

Reverse prods. Observe reading.

If readings are identical, replace

rectifier bridge. Repeat procedure

with remaining two terminals.

Connect prods to insulated heat

sink and one of three terminals.

Observe reading. Reverse prods.

Observe reading. If readings are

identical, replace rectifier bridge.

Repeat procedure with each of

two remaining terminals

3-42