Rotation Failure - How does my rotation sensing circuit work?

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Rotation Failure - How does my rotation sensing circuit work?
(Error - Rotation Failure) The dryers have a proximity switch and target on the discharge side of the basket idler shaft. The target is mounted to the shaft and rotates as the shaft rotates.
The basket idler shaft has a target mounted to the end of the shaft. When the shaft rotates the target rotates as well. This engages a proximity switch that sends signals to the Safety Rotational Board. If it does not see the target come around in an allotted time, the "Rotation Failure" error appears.

The rotation prox will make an input on the BIO1 (Highspeed I/O) and the Safety Rotational Board. The input on BIO1 calculates dryer RPM. The input to the Safety Rotational Board determines if relay CRRSM is energized. CRRSM makes the "Dryer is Rotating" input on BIO1 at Pin 6.  

If a rotation failure occurs, check on reasons the drive shaft may not be rotating. This can result from a number of things including but not limited to:
  • Jammed basket
  • Bearing failure on the idler shaft causing the prox switch not to sense the target
  • Motor failure
  • Inverter failure
  • Loose rotation target
  • Prox switch out of adjustment
  • Condensate on the basket drive wheels causing slipping of the wheels on the basket - in this case the dryer blower can be run manually before starting to dry the condensate which usually occurs overnight.  

08BNDSRAT - Safety Rotational Board



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Rotation Prox Location - Rear of Dryer

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