1. Inspection and log in of motor before disassembly
a. Identification of leads
b. Mechanical Configuration
d. Generated voltage / waveform / balance
f. Tachometer output and waveform
g. Auxiliary devices
2. Inspection of motor after disassembly
a. Bearings, Shafts, and Housings
(Tolerances and sizes)
b. Windings (Thermal aging, Brittle leads, etc.)
c. Permanent Magnets
(Looseness, Cracks, Flux density etc.)
d. Brakes (Must be within brake wear limits)
e. Encoder / Resolver (Inspected for proper
operation before dismantled)
f. Auxiliary devices (Inspected for proper operation)
3. Repairs to Servo Motors
a. Repairing or rewinding of stator: Spray wash
then oven dry to remove oil and contaminants, or
replace winding with spike resistant wire and
b. Mechanical tolerances: All bearing housings,
shaft, rabbet fits are to be examined and made
sure they meet manufacturers specifications.
c. Reassembly of motor: Motor reassembled with
manufacturers specified or better bearings and
new or repaired electrical components.
4. Testing of Servo motors
a. Check windings: Test windings with Hipot,
Megger, and Ohmmeter for resistance to frame
and resistance in windings.
b. Re-install and time feedback device using static
lock-up and oscilloscope.
c. Back drive motor: Place motor on test stand to
drive motor so that feedback devices may be
d. Using Mitchell equipment, check motor timing,
test, and count test, continuous count test and
symmetry test of feedback device.
e. Load test motor and record all performance