TM 9-4120-385-14
WARNING
High voltage can kill.
1.
D iSCOnneCt power
supply.
2.
Remove
motor from casing. Refer to Paragraph 4-24.
DISASSEMBLY.
b.
1.
Remove four screws (2) horn front bracket (3).
2.
Using a rubber mallet gently tap motor shaft through frame and stator assembly
(22) and remove shaft assembly (8) and front bracket (3).
3.
Carefully pull rotor and shaft assembly (8) out of frame and stator assembly (22).
Inspect frame and stator assembly for damage.
4.
Using a bearing puller, remove bearings (7) from motor shaft. Bearings should
be inspected for wear, flat spots, and heat discoloration. Inspect motor shaft for gouges or worn
bearing surfaces.
Disconnect power supply from unit.
5.
Spin impeller fan. Motor should turn freely without roughness.
6.
7.
Using a multimeter, check connector pins A to B, C, D, E, B to C, D, E, C to D, E,
D to E for continuity. If continuity is not indicated, motor is defective. If impeller fans do not
turn freely, bearings may be defective. Refer to Paragraph 4-25 and Paragraph 5-10.
c.
REPAIR.
1.
Repair damaged bearings by replacement.
2.
Repair damaged rotor and shaft by replacement.
3.
Repair damaged rotor core windings by replacing the entire motor or having the
motor rewound. Refer to Table 5-8 for motor burnout test.
Table 5-8 MOTOR BURN-OUT T E S T
PROCEDURE
STEP NO.
Motor must be fully assembled to perform test.
1
Use a megger set on the 500 V range.
2
Place one probe on the motor case and the other probe on
3
pins A, B, C, D, or E.
4
If less than 12 megohms is indicated, the motor should be replaced
or windings replaced.
