Procedure 5.3 - Troubleshooting The Speed Sensor - Precor 9.31 Manual

Procedure 5.3 - Troubleshooting the Speed Sensor

Note:
The speed sensor is an optical sensor that emits a pulse when an interrupter lobe passes
between it's transmitter and receiver. The speed control circuit processes the pulse train emitted
by the speed sensor. The speed sensor signal is a real time representation of the operating
speed of the treadmill. The speed control circuit compares the real time speed (speed sensor
output) with the speed that it expects the treadmill to be operating at and acts accordingly to
control treadmill speed or initiate an error code sequence, if necessary. Typically, if a problem
exists with the speed sensor the drive motor will operate (perhaps only briefly) before a speed
related error occurs (errors 20-26).
1. Remove the treadmill's motor cover and set the treadmill's circuit breaker in the "on"
position. Using a DC voltmeter, measure the voltage between terminal 3 of J3 and terminal 4
of J3 on the lower PCA. Slowly, rotate the drive motor flywheel. The voltage should read
approximately 0.25 Vdc when a flywheel lobe is between the speed sensor "legs" and
approximately 5 Vdc when a flywheel lobe is not between the speed sensor "legs".
Diagram 5.3 - Speed Sensor Mounting
2. If the voltages in step 1 are correct, skip to step 5. If the voltage in step 1 is 0 Vdc or
significantly low when a flywheel lobe is between the speed sensor "legs', continue with step
3.
9.31, 9.33, 9.35 Treadmill
Interrupter
Speed Sensor
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