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.
Figure 4-6. Stator winding test..
Remove screws (12) and remove brushholder (18) and
(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
Refer to d. above and remove the
attempt to polish by hand. Cleaning without
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).
(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).
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
(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
g. Brush Holder and Regulator Replacement..
(1) Remove diode ((1. above).
(2) Disconnect stator (29, fig. 4-1) from