Model # WTW6200SW0
, this top load washer would intermittently display an error message during a wash cycle requiring the load to be started again after clearing the display. The problem was infrequent at the beginning, but continued to get worse with time. After trying different sized loads thinking there may be some correlation, the customer finally called for service to get it fixed.
The F51 error is a RPS (rotary position sensor) board failure where the control board looses contact with the RPS during the machines operation. The RPS uses hall effect sensors to determine the speed and direction of the drive motor, allowing the control board to constantly monitor the motors operation. Because this error is a communication error and not a mechanical error with the motor itself (that would be and F52 error) we can limit our trouble shooting to the three items that make up the RPS circuit, the control board, the wiring harness, and the RPS itself.
Looking at the wiring diagram for the RPS circuit, we will find a wiring harness consisting of brown wires connecting to the top of the control board. From here, we can test for our output voltage on pin 6. As long as we have our 15vdc on this pin, that indicates the control board is working. Our next stop is under the machine to locate the RPS board.
Tipping the machine back will reveal the motor directly underneath the tub. The RPS board is mounted on the right side (follow the brown wires) and under the motors rotor disk. An Allen wrench is used to remove the rotor and then the four bolts holding the motor stator to the tub can be removed. Once the motor is out, we can get to the RPS and the wiring harness and do a continuity check on each wire between each end of the harness. If our readings indicate a good harness, we are down to the RPS itself and it would need to be replaced. Of course there is one other thing to do, and that is make sure the connection from the harness to the board is good.
Many of these boards were manufactured with a clear lacquer being applied to the boards to protect the wire traces, and unfortunately, many of the contacts themselves became covered. This results in a poor connection to the harness connector and provides for an poor intermittent signal to the control board. To repair this unit, I removed the RPS board and using my jewelers file, cleaned the contacts for proper electrical connection. Once everything was reassembled, it ran two complete diagnostic cycles without a hiccup. And now the customer can get some laundry done without restarting the machine.
(RPS) Rotor Position Sensor Part # W10183157