Troubleshooting The Drive Motor System - Precor Energy Series Service Manual

Troubleshooting the Drive Motor System

The drive motor controller is a PWM (pulse width modulated) system that limits the drive motor
current to 28 amps. The lower PCA has several LED indicators to depict lower PCA status.
Procedure
1. If the MOT DRV LED is illuminated, replace the lower PCA board. The MOT DRV LED
typically indicates a component failure on the lower PCA.
2. If the drive motor starts briefly then stops and an error 26 is displayed, troubleshoot the speed
sensor. If the drive motor does not start and an error 26 is displayed, continue with next step.
3. Remove the treadmill hood.
Warning : The treadmill will be operated with the hood removed in this procedure. The service tech
will be exposed to both electrical shock hazards and mechanical hazards. Extreme
caution must be exercised to avoid contact with exposed electrical connections and
moving parts.
1. Connect the AC power cord and set the on/off switch to the "on" position.
2. Start the treadmill to operate in the manual program mode at 1 mph.
3. Measure the DC voltage between the T3 (M+) terminal and the T4 (M-) terminal on the lower
PCA. The voltage should be approximately 12 Vdc. If the voltage is absent or significantly low
and/or the PWM LED does not illuminate, skip to step 7.
4. If the PWM LED does illuminate and the DC voltage is approximately 95 VDC the drive motor
is an open circuit. The most probable reason for the motor to be open is a badly worn motor
brush.
5. Set the on/off switch in the "off" position and remove the AC power cord from the AC outlet.
Remove the drive motor wires from the lower PCA (red, T3-M+ and black, T4-M-). Measure
the resistance between the two wires, the resistance should be approximately 4.6 ohms. If the
resistance is infinite ohms (open) or significantly high, check both motor brush lengths are long
enough to make solid contact with the motor commutator to make good electrical connection
at the brush holder (new motor brushes are about 3/4 inches long). If necessary replace the
brushes.
6. If the motor brushes to brush contact is good and the drive motor wire resistance remains
open or significantly high, replace the drive motor.
7. If either the MOT DRV or SHUT DOWN LED is illuminated on the lower PCA, replace the
lower PCA.
8. If the speed indicator does not increase when the SPEED UP key is pressed, the problem is in
either the keypad or the upper PCA. Troubleshoot the keypad. If the keypad is defective,
replace the console.
9. If the keypad is good and the display still does not indicate that the speed is increasing when
the SPEED UP key is pressed, replace the upper PCA.
10. If the display does not indicate that the speed is increasing when the SPEED UP key is
pressed, bypass the Dara cable with a known good Data cable. Tip; It is not necessary to
install the bypass cable, just connect it between the upper PCA and lower PCA. If the drive
motor functions normally with the bypass cable installed, replace the data cable.
11. If the drive motor does not function normally with the bypass cable installed, replace the lower
PCA. If you have performed all of the procedures above and have been unable to correct the
problem, call Precor customer support.
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