HELP: Minimoog Model D, 4th Oscillator (?) constant sound

[Intervene]

Hi, i have searched all over the internet for this problem,
but i cant find any clues so here it goes.

Since one day i turned on my Minimoog Model D, a constant note is oscillating
in the background, regardless of what outputs im using, and regardless of which,
or how many of my, oscillators that's turned on. I does'nt seem to
go through the filter, or the ADS-envelope, and sounds to me as something between
a sine wave, and a triangle wave.

The sound is there independent on wether i touch the keyboard or not, and the sound is not in any way
affected by any of the knobs on the front.

So now i have decided to take it to somebody who can fix it, but
he is not a synth expert so he wants to know where he can look for the problem in the circut schemes.
If anyone has any idea on what the problem could be, or where i can look for the problem
it would help me alot!

All help is much appriciated, it would made my day!
(Perhaps my week)

-A from Norway.

[meatballfulton]

Make sure you have the A440 tuning tone turned OFF

[garranimal]

I probably wouldn't let anyone who didn't know how to operate a synth, troubleshoot a synth. No matter how good an EE or tech they may be. But it does appear your question is already answered hopefully. Have fun w/ your mini!

[snod_donkey]

Well if its not the 440 test tone it could well be it requires a retune and set up.... im sure i had an issue on one of mine the same
Has the fault just started and it had been fine before or always been there since you got it?

[Intervene]

The A440 turning was obviously a good place to start,
even tho it was set to off, it seems something was stuck in place, so
opened it up, and after a few sets back and forth, i got back in right place!

For some reason i remembered the test tone to pass through the filter section
so i was convinced the testtone that was not the case, but as i said, all help appriciated,
so thanks a lot for the suggestion meatballfulton! I had to start somewhere i guess!

[Z]

There would be any point in sending the test tone through the filter. If the filter cut-off was set low or to zero, the sound would be faint or non-existant.

Because analog oscillators tend to drift out of tune, between songs you could turn off the main output switch on the Mini, tune the oscillators with headphones and turn the main output back on.

Glad you got the issue resolved.