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TM 10-3930-671-24
3.
To remove brush assembly from the rear
housing, grasp field terminal and gently apply
outward pressure to brush assembly to clear two
positioning tabs on rear housing. As brush
assembly clears tabs, continue to pull the brush
assembly down and away from housing (Figure
No. 20).
FIGURE NO. 20.
If in the process of brush removal, the brush cover
gasket (Figure No. 21) should become damaged or torn,
it must be replaced and positioned properly.
NOTE
The
brush
shunt
lead
insulator
insures that the brush assembly
braided leads (Figure No. 21) do not
touch the rear housing and ground
the field. Should this insulator
become damaged, or torn, in the
removal of brush assembly, it must
be replaced and positioned properly.
FIGURE NO. 21.
BRUSH ASSEMBLY INSULATION TEST -
A.
Insulation Test: Connect ohmmeter or a test
lamp (12 volts) to field terminal and bracket (test points A
and D, as shown in Figure No. 22.
Resistance should be high (infinite) or test lamp should
not light. If resistance is low, or test lamp lights, brush
assembly is shorted and must be replaced.
Alternator brush is constructed of
semi-soft
material
that
is
easily
broken. Use care not to chip brush
during testing.
B.
Continuity Test: Connect an ohmmeter to field
terminal and brush (test points A and C). Use an
alligator
clip
to
assure
good
contact
to
brush.
Resistance reading should be zero. Move brush and
brush lead wire to make certain that the brush lead wire
connections are not intermittent. Resistance reading
should not vary when brush and lead wire is being
moved around.
C.
Connect ohmmeter to bracket and grounded
brush (test points D and E). Resistance reading should
be zero. Repeat same test on brush lead wire as
described in paragraph "B".
FIGURE NO. 22.
F-286
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