ELECTRICAL CHECKS

ELECTRICAL

5. The bearing in the slip ring end frame should be

replaced if its grease supply is exhausted. No attempt

should be made to relubricate and reuse the bearing.

6. If the slip rings are dirty, they may be cleaned

and finished with 400 grain or finer polishing cloth. Spin

the rotor in a lathe, or otherwise spin the rotor, and hold

the polishing cloth against the slip rings until they are

clean.

CAUTION: The rotor must be rotated in order that

the slip rings will be cleaned evenly. Cleaning the

slip rings by hand without spinning the rotor may

result in flat spots on the slip rings, causing brush

noise.

Slip rings which are rough or out of round should be

trued in a lathe to .002 inch maximum indicator reading.

Remove only enough material to make the rings smooth

and round. Finish with 400 grain or finer polishing cloth

and blow away all dust.

E. ELECTRICAL CHECKS

1. Rotor:

Figure 11.

NOTE: The rotor may be checked

c. The winding is checked for short-circuits by

electrically for grounded, open, or

connecting a 12-volt battery and ammeter in

short circuited field coils.

series with the two slip rings. Note the ammeter

reading. An ammeter reading above 2.3 amperes

a. To cheek for grounds, connect a 110-volt test

indicates shorted windings.

lamp or an ohmmeter from either slip ring to the

rotor shaft or to the rotor poles. If the lamp lights,

NOTE: If the rotor is not defective,

or if the ohmmeter reading is low, the field winding

and the alternator fails to supply

is grounded. (Fig. 11)

rated output when checked, the

trouble is in the stator or rectifying

b. To check for opens, connect the test lamp or

diodes.

ohmmeter to each slip ring. If the lamp fails to

light, or if the ohmmeter reading is high (infinite),

2. Stator:

the winding is open. (Fig. 11)

NOTE: To check the stator windings,

remove all three stator lead attaching

nuts (Fig. 12) and then separate the

stator assembly from the end frame.

a. The stator windings may be checked with a

110-volt test lamp or an ohmmeter. If the lamp

lights, or if the meter reading is low when

connected

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