Slip Ring Service.

TM 10-3930-630-34

Rectifier Bridge Test.

(1) Connect an ohmmeter to the

grounded heat sink and to one of the three terminals as

shown on figure 4-5. Check ohmmeter reading. Reverse

ohmmeter connections and again check reading. If both

readings are the same, replace the rectifier bridge. A

good rectifier bridge will give one high and one low

reading. Check each terminal against the heat sink in

the same manner.

TA067403

Figure 4-6. Stator winding test..

Remove screws (12) and remove brushholder (18) and

brush (19).

(3) Remove screws (16) and regulator

(17) from frame (11).

(4) Install regulator (17) in frame (11) and

secure with screws (16).

(5) Install new brush (19) in brushholder

(18) and install brushholder in frame (11) and secure

with screws (12).

h. Slip Ring Service.

(1) If slip rings are darkened or dirty,

clean rings with fine sandpaper or polishing cloth.

Figure 4-5. Rectifier bridge test.

(2) Spin the rotor (15) and hold

sandpaper against slip rings until they are clean. Do not

(2)

Refer to d. above and remove the

attempt to polish by hand. Cleaning without

diode.

spinning slip rings may result in flat spots on rings.

(3) Disconnect capacitor (28, fig. 4-1)

(3) If slip rings are rough or out of round,

from heat sink.

place rotor in a lathe and check rings with a dial

(4) Remove screws (21) and washers

indicator. Maximum allowable out of round is 0.002 inch

(22) and remove rectifier bridge (24) from frame (11).

(0.05 mm).

(5) Install new rectifier bridge (24) and

(4) Refinish rings removing only enough

secure with screws (21) and washers (22).

material to correct out of round conditions. Polish rings

(6) Connect capacitor (28) to heat sink.

as described above and blow out rings to remove dust.

Install diode (d. above).

Bearing Replacement.

Stator Winding Test.

(1) Remove stator (29, fig. 4-1) from

(1) Connect an ohmmeter between the

drive end frame (14).

stator leads as shown in figure 4-6. If the meter reading

(2) Remove screws (30) and bearing

exceeds normal winding resistance when connected

retainer (31). Remove spacer (32).

between each pair of leads the windings are open.

(3) Use a suitable tool and press bearing

Replace windings.

(33) and oil deflector (34) from frame (14).

(2) Connect ohm meter between stator

(4) Pack bearing one-quarter full of

lead and mounting ring as shown in figure 4-6. If a

grease (GAA). Install oil deflector (34) in frame (14).

reading is obtained, winding is grounded. Replace

Use a

winding.

g. Brush Holder and Regulator Replacement..

(1) Remove diode ((1. above).

(2) Disconnect stator (29, fig. 4-1) from

brush.

4-4