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Servo Motor Resistance Test
Figure 1 - Resistance Measurement of Servo Motors
Servo Mtr Resistance Specication
X 3.65±10%Ω
Y 2.28±10%Ω
Z 1.04±10%Ω
When measuring the resistance with a ohmmeter or multimeter, it is strongly recommended that it be
done with a calibrated meter rated with resistance reading accuracy equal to or better than ±1%. Fluke
™ multimeters generally meet this accuracy requirement. Make sure you get this specication when you
purchase multimeters used to troubleshoot machine errors.
If you use a meter that does not meet this accuracy specication, go on the assumption that if the read-
ings between the phase leads of the motor are consistent (nonzero resistance) that the motor is probably
good. The machine should be considered defective if the measurements are substantially lower than the
ranges specied in Step 1 shown in the above table. If you have a phase that has close to a zero reading
or measurements between phase leads that are not consistent, then the motor is defective.
“Ohming out a motor” or measuring the resistance between each of the phase wires is easily measures
by connecting the leads from the meter to the non-ground wires (disregard the green wires). The resis-
tance between each of the phase combinations (3 combinations on all three servo motors) should be
consistent and within the ranges shown in Step 1 in the table above.
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