I have a DX7 that's in perfect working condition (been using it for a few years) but when I plug in a sustain pedal (third-party or Yamaha Fc5) it just acts like it's on, whether the pedal is depressed or not. As soon as I press a key, the sustain begins and it won't stop until the pedal is unplugged.

I've tried the "turn the DX7 off, then depress the pedal and turn it back on" trick, as well as the reverse of that (turn off while depressing pedal). The Fc5 doesn't have a polarity switch, but the third-party one does, and I've tried every combination of setting and on/off I can think of, to no avail. I've also opened the DX7 to look at the plug, and while I'm no expert, it at least appears to be in order.

Could there be a setting that I'm missing? Or are there any other suggestions? I'd really appreciate any help, hints, clues, winning lottery tickets. Thanks!

  • Plug the pedal into the jack marked 'Sustain' before powering up the DX7. Play a note. Does it continue to sustain whether the pedal is up or down? Does it act the same with both of the pedals you have? Does it act the same for any selected sound on the DX7? If so, I can't see any possibilities other than a fault in the DX7. Sorry.
    – Laurence
    Mar 8, 2023 at 2:03
  • Do you have the latest version of the firmware installed?
    – empty
    Mar 8, 2023 at 2:08
  • Hi Laurence, yes, it continues the sustain whether the pedal is up or down. With either pedal, and with any sound. I suspect it's the hardware but I was hoping that just maybe it had to do with some setting. Mar 8, 2023 at 6:42
  • Does it behave if you don't plug the pedal in at all, or unplug it sometime during the experiment?
    – Tetsujin
    Mar 8, 2023 at 9:49
  • Did it ever work properly using the FC5 pedal?
    – Tim
    Mar 8, 2023 at 15:43

1 Answer 1


Just a guess - I sold my DX7 20 yrs ago.

The jack socket is most likely a switched socket, which dis/connects some circuitry when the jack is inserted. Maybe it's broken, or just dirty. Switch cleaner sprayed into that socket, and the jack pushed in/out many times, may solve the connectivity. Certainly worth a try, before taking it to a Yamaha mechanic, who, undoubtedly, will be able to replace the socket, even if you can't.

I'll try to contact a friend who still has one ( I repaired it several yrs ago) for any advice.

EDIT: friend never used a pedal with his DX7, so no help. Regarding the faulty (?) jack socket you could try moving the plug up/ down, laterally while it's in, that may point to what I think is the problem - a dirty or broken socket, or at least one which isn't accepting the jack properly.

  • Tetsujin: Yes, it acts that way any time the pedal is plugged in. Tim: Thanks I'll try that. Mar 8, 2023 at 15:13
  • Well, it's a faulty socket. Taking Tim's advice I tried moving the plug around. Pulling down on it (making the tip inside the socket go up), made the connection and pedal work as it should. When I get a chance I'll open up the unit and see if it's something I think I can repair. Thanks! Mar 9, 2023 at 2:53

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.