Precor Error 10, Line Frequency out of Acceptable Range

Probable Cause

1. Treadmill is connected to a non-dedicated AC circuit
2. The AC hot and AC neutral wires are reversed on a 120VAC circuit.
3. The upper PCA has an incorrect jumper setting.
4. Fuse feeding the stepdown transformer is bad.
5. AC line frequency is incorrect.
6. AC line may be excessively noisy.

Corrective Action

  1. Treadmill must be connected to a completely dedicated 20amp AC circuit.  Both hot and neutral leads must be dedicated to the treadmill. If the circuit is shared with another piece of equipment, it can cause enough electrical noise to make the AC line frequency impossible to identify. The AC circuit for the treadmill must be re-configured as a completely dedicated 20amp circuit.
  2. Many line frequency detection systems observe the AC line frequency on the hot AC line.  In the event of a reversed 120VAC circuit, the observation is taking place on the neutral (ground) part of the AC line.  Many observing systems are not capable of detecting line frequency on the neutral line.  First it must be determined if the reversal is in the AC wiring feeding the treadmill or in the internal wiring of the treadmill.  The hot and neutral lines can be confirmed by measuring each in reference to AC (green wire) ground.  The hot wire will read full line voltage (commonly 105 - 120VAC) and the neutral should read about 0VAC.
  3. The upper PCA's for some units had a jumper setting for use with SCR or PWM drive circuits.  If the jumper was set on the upper PCA as PWM on an SCR unit, the Error 10 appears.  Change the jumper setting to SCR to correct the problem.
  4. A pair of fuses were used on some treadmills (C944 PWM version 2 and C96x PWM version 2) that fed the stepdown transformer for the low voltage power supply on the lower PCA.  The AC line frequency was observed on the output of one of the fuses.  If the fuse blew, AC line frequency could not be detected even though the treadmill appeared normal under other circumstances.
  5. It is unlikely, however, the AC line frequency could be out of acceptable limits.  This would more likely occor in countries were AC power systems may not be well developed and controlled.  There is little that can be done to correct this issue.  If the source frequency cannot be corrected, the only possibility would be replacing the treadmill with one that utilizes a PWM motor controller.  PWM motor controllers do not depend on line frequency for speed control.
  6. At times the AC being fed into the distribution system is too electrically noisy to allow correct line frequency identification.  This can be caused by other equipment within the AC distribution system creating the electrical noise.  It can be difficult to identify the source of the electrical noise.  There is little that can be done to correct this issue.  The source needs to be located and removed or made electrically quiet.  If this cannot be done, the only possibility would be replacing the treadmill with one that utilizes a PWM motor controller.  PWM motor controllers do not depend on line frequency for speed control.