(6) Inspect brush holders for defects. Replace
Key to figure 3-7.
defective brush holders.
1 Nut (2)
31 Holder
2 Washer (2)
32 Holder
(7) Measure brush spring tension. Replace springs if
3 Bolt (2)
33 Nut (2)
tension is less than 28 ounces.
4 Washer(2)
34 Washer (2)
5 Bolt
35 Washer
(8) Check for short circuits in armature by rotating
6 Washer
36 Washer
armature on a growler with a hacksaw blade held firmly
7 Clamp
37 Screw
on armature. The hacksaw blade will vibrate on the area
8 Screw
38 Washer
of the short circuit. If short circuits are found, clean
9 Washer
39 Capacitor
spaces between commutator bars using an undercutting
10 Brace
40 Nut (2)
tool and cleaning with compressed air. If a short circuit
11 Nut (2)
41 Washer (2)
cannot be removed, replace generator.
12 Washer(2)
42 Washer
13 Bracket
43 Washer
(9) Check for open circuits by inspecting for loose
14 Stud (2)
44 Bushing
connections at points where conductors are connected to
15 Nut
45 Screw(2)
the commutator risers. Check continuity between
16 Washer
46 Coil
adjacent commutator bars. If open circuit cannot be
17 Pulley
47 Screw
cleared, replace generator.
18 Fan
48 Armature
- 19 Key
49 Spacer
(10) Check for ground by checking armature with a
20 Bolt (2)
30 Screw (3)
test lamp. Place one probe of test lamp on armature core
21 Washer {(2)
51 Washer (3)
and the other on each commutator bar in turn. If test
22 Head assy
52 Retainer
lamp lights, armature is grounded. Clean armature
23 Oil cup
53 Gasket
thoroughly and recheck for grounds. If ground cannot be
24 Wick
54 Bearing
repaired, replace generator.
25 Cover
55 Washer
26 Bearing
56 Packing
(11) Check field coils for grounds using a test lamp.
27 Screw
57 Wick
Place one probe of test lamp on field body assembly and
28 Washer
58 Retainer
the other on the field coil leads. If test lamp lights, field
29 Brush set
59 Head assy
coils are grounded. Replace generator if field coils are
30 Spring (2)
grounded.
b.
Cleaning, Inspection, and Repair.
(12) Check field coils for open circuits using a test
(1) Wipe all parts, except brushes, with a cloth A,N
lamp. Connect probes of test lamp to the two leads from
lightly dampened in an approved cleaning solvent.
the coils. If lamp does not light, coil is open. Replace
(2) Wipe brushes with a clean dry cloth.
generator if field coils are open.
(3) Inspect armature bearing for worn surfaces,
looseness, cracked ring or race. Replace defected
d. Reassembly.
bearing.
(4) Check size of brushes. Replace them if they are
(1) Refer to figure 3-7 and reassemble generator.
less than one-half length of a new brush, or if worn within
1/8" of brush holder.
(2) Perform generator output test (TM 10- 3950-203-
20).
CAUTION
e. Installation. Install generator (TM 10-3950- 203-
20).
Always blow dust particles off commutator in the
direction away from armature windings.
3-8. Starter
(5) Inspect armature commutator for roughness,
a. Removal. Remove starter (TM 10-3950-203-20).
out-of-round or high mica. If any of these conditions exist
b. Disassembly.
turn commutator down on a lathe and undercut mica
(1) Match-mark end frame, pinion housing, and field
1/32 inch. Finish commutator with No. 00 sandpaper.
frame.
Use compressed air to clean all dust particles from
(2) Refer to figure 3-8 and disassemble starter.
commutator and armature.
3-13
