I connected by mistake the my "standard" Stagg sustain pedal to the modulation on the back of my Yamaha DX7 mkI. That resulted on changing to sound to very high pitch and I don't know how to revert this.

I have tried to disconnect from power, waited a few minutes, but when I brought it back, high pitch is set through all the patches :(

Did I break something?


My guess:

  • The sustain pedal is a basic one that only sends on/off
  • The polarity on the sustain pedal is "reversed", so that not pressed sends max value
  • The DX7 sees this as "mod pedal to full"
  • The DX7 remembers the state of the mod pedal, so it can have the right mod value upon power-on. So it's stuck now.

If I'm right, then you should be able to fix it by plugging the pedal back in, depressing it, and unplugging it while depressed.

  • your suggestion does make a lot of sense indeed. I did try but no luck. Still stuck in that weird state. I will persist – zabumba Dec 10 '17 at 2:03
  • As a matter of fact, I have a MOOG Moogerfooger-EP-3-Expression-Pedal 111520, which I tried, and it has little effect on the modulation and didn't reset the state – zabumba Dec 10 '17 at 2:10
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    At a guess, it may be capable of sensing the polarity/state of a pedal as it is inserted. Insert the pedal with the machine off; switch on & see if pressing/releasing the pedal makes any difference at all. If so, switch the machine off when the desired state is reached, then unplug the pedal. [Otherwise give Yamaha a ring, the main distributors for US/UK/EU are easy to find online. Their tech/repairs dept will know what to do & their advice is free] – Tetsujin Dec 10 '17 at 8:10
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    I tried your suggestion, and it worked. Thanks – zabumba Dec 10 '17 at 19:19

Work the plug in and out of the Modulation socket a few times. It's possible that the contacts on this normally unused socket are dirty (this is hardly a new instrument!) and the bypass when no plug is inserted isn't working.

  • very good suggestion. I did try a few times and it ended up bringing everything back to normal! Relieved. Thanks – zabumba Dec 10 '17 at 19:21
  • Good. Wanna accept my answer, then? – Laurence Payne Dec 10 '17 at 21:22
  • sorry I meant that I had fixed my problem prior to reading your message. The accepted answer is the one that brought me to resolution. However it took me several tries, hence my upvote on this answer too. I hope you will understand. Again, thank you for the suggestion, hope it will help others that will get cornered into the same problem. Similarly you could also upvote the "good" question ;) Cheers – zabumba Dec 10 '17 at 21:30
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    I suspect it was the unplugging and replugging while you 'gave it a few tries' that fixed it, rather than what you did to the pedal when it WAS connected! The Mk I DX7 wasn't that sophisticated an instrument to remember pedal settings. However, it's sorted. Good! – Laurence Payne Dec 10 '17 at 22:58

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