Repairing A Dropped WX7 With A Slipped Key PCB

Did you drop your WX7? Is it now playing only one note, no matter what keys you press. If so, then your WX7 is suffering from "dropped on the floor" syndrome, where the key PCB inside has shifted relative to the key plungers, and now it only plays in C# (no keys pressed). This typically happens when the WX is dropped on the tail end, and while the WX body stops abruptly when it hits, the PCB inside keeps sliding down. While Yamaha did put in a small alignment tab on the upper rear cover, that probably has sheered off too and you now have the little tab rattling around inside (or hanging on by a thread and about to rattle around.

  1. Take off both the upper and lower rear covers. You will need to loosen the thumb bender screws before you can remove the lower cover.
  2. Inside you will see the key circuit board at the flat gray slab that runs nearly the length of the keyworks. Wedging the flat gray slab into place are a number of ivory colored plastic pieces along each side. There are 6 or 8 of these. Make sure these ivory plastic pieces are in place, up firmly to the sidewalls of the WX body.
  3. Now, gently slide the gray key PCB up until the bottom of the PCB is aligned with the brass (BeCu, actually) grounding U-piece with the black wire soldered to it. Another way to determine the position is to look at the scrape marks the ivory pieces made on the gray slab during the shifting of the PCB.
  4. Once you've got the PCB back into position, test it via careful hook-up while it's still open.
  5. Don't forget to find and remove the little locating tab that probably broke when the board slid.
  6. Once it works, put it back together and it's as good as new.

BTW: I made an L shaped plastic piece that lays inside at the foot of the WX, and a piece of thin foam glued to the short leg of the L. The short leg w/foam is up against the key PCB, waiting to gently hold the PCB in place should the WX be dropped. Eventually, I'll glue the accelerometer circuit to this plastic piece. Also, I put my name on the plastic, so that should my WX ever be stolen, I can prove it's mine - of course, who else has a FSR installed behind the neckstrap ring???