REPAIR INSTRUCTIONS
ELECTRICAL SYSTEM
Section I.
the exposed surf ace of the armature
116. Generator
core. A short circuited coil in one of
a. Removal and Disassembly.
the slots bridged by the jaws of the
(1) Refer to paragraph 64 and remove the
growler will cause the steel strip to
vibrate when brought close to the
(2) Refer to figure 32 and disassemble the
other slot occupied by the defective
coil; however, inspect the commutator
b. Cleaning, Inspection, Testing, and Repair.
slots carefully for copper or electrical
(1) Clean all metal parts, with the excep-
contact brush dust which may collect
tion of bearings, coils and armature,
in the slots and cause shorts. Turn the
with an approved cleaning solvent and
armature in the growler one slot at a
dry thoroughly.
time until all coils have been tested.
(2) Inspect all parts for cracks, breaks,
Replace a defective armature.
wear, and other damage or defects.
Caution: During the following out-
Replace all defective parts.
lined open and ground tests, do not
(3) Inspect the bearings for roughness or
touch the test probes to the armature
excessive play when rotated. Replace
shaft bearing surfaces or the commu-
defective bearings.
tator, for arcing may mar the sur-
(4) Inspect the brushes for wear, cracks,
faces.
chips, or breaks. Replace if necessary.
(9) Test the armature for open circuits
(5) Inspect the brush springs for proper
with a growler. Position the armature
tension and distortion. Replace a
on the growler and energize the
brush spring that is distorted or has
growler circuit. With the test probes
a spring tension of less than 28 ounces.
connected to an AC voltmeter, select a
(6) Clean the armature with a clean, lint-
pair of commutator bars which give
free cloth dampened with an approved
a readable indication on the voltmeter.
cleaning solvent and dry thoroughly.
Maintaining this relation between the
Inspect the armature for roughness,
test probe position and the growler,
high mica, or burning of the commu-
turn the armature one slot a time
tator. Turn the commutator down in
until all coils are tested. The volt-
a lathe to remove roughness or high
meter readings should be clearly uni-
mica. Use a hacksaw blade or under-
form. If the armature has proven free
cutting tool to undercut the mica to a
of shorts a low or zero reading indi-
depth of one thirty-second inch be-
cates an open circuit. Replace a defec-
tween the commutator bars.
t i v e armature.
(7) Inspect the armature shaft for burrs,
(10) Test the armature for grounds with a
pita, or excessive wear. Inspect the
test lamp circuit. Test between the
armature core for loose windings. Re-
armature shaft or core and one of the
place the armature if windings are
commutator bars. Repeat the test at
loose or the armature is unserviceable.
two or more locations around the com-
mutator to preclude the possibility of
(8) Use a suitable growler to test the
testing from an isolated bar. If the
armature for shorts. Position the
test lamp lights, the armature is
armature on the growler and energize
grounded. Replace a defective arma-
the growler. Hold a thin steel strip
ture.
parallel to the core slots and explore
AGO 8166A
