TM 9-4940-549-14&P
Visually inspect rotor assembly for rub marks and burns or
(8)
other evidence of shorting. Inspect shaft for worn key slot
and bearing surfaces.
Test rotor assembly as follows:
(9)
(a) Install rotor assembly in test set-up as shown in figure
7-7.
(b) Adjust rheostat until voltmeter indicates 20-Vdc.
(c) Ammeter should indicate 1.28 to 1.88 amperes at 70 to
80F (21.1 to 26.7C).
(d) High current indication on ammeter indicates excessive
internal resistance in rotor assembly.
(e) Using an ohmmeter, check resistance across slip rings.
Resistance should be 11.0 to 14.0 ohms at ambient temper-
ature of 70 to 80F (21.1 to 26.7C).
(10) Replace rotor assembly if inspection and test requirements are
not met.
(11) Inspect voltage regulator connector and cover assembly for cracks,
corrosion, and evidence of shorting or other damage.
(12) Inspect fuse holder for cracks, corrosion, and other damage.
Check fuse for burned out condition. Check fuse for continuity
if in doubt.
(13) Inspect brush assembly for corrosion and excessive wear.
NOTE
The brushes are excessively worn if
3/16-inch or less extends beyond the
bottom of the holder.
A force of 4 to 6 ounces should
(14) Check brush spring tension.
move brush against spring.
(15) Using an ohmmeter, test brushholder assembly as follows.
(a) Attach one test lead to brushholder and touch other lead
to each terminal and each brush. There should be no
indication of continuity between brushholder and any termi-
nal or brush.
(b) Check for non-continuity between each terminal and its
respective brush.
(16) Replace brushholder assembly if inspection and test require-
ments are not met.
7-19
