Moog Music Forum

Hello hello,

I've came across a Mini with a strange issue, and wonder if other have experienced that.

It is a "old" oscillator board with a probably faulty osc 3. If I get my hand near the board, the pich changes dramatically (I mean it is very very very unstable). If I move in front of the mini (doing some Mashed Potato or trying to invoke rain) the pitch changes. If I move the Modulation Mix knob from his min ou max values, the pitch drops, with the osc 3 being in the normal operation mode. When I say "the pitch changes", I mean it could drift of a semitone.

I have plugged a "new" oscillator board in there and it was perfectly working. I have checked the usual suspects like ceramic caps, transistor array, op amps, they're all good.

I am suspecting a ground issue but I'd like to know if swapping old and new boards without problem is normal?

Any idea appreciated!

Thanks

Hi:

Have you found a solution to this issue? I just changed all the electrolytics, installed temperature compensated op amps, put in 20-turn pots for tuning, and a new Fatar keyboard in my 1974 Mini Moog D and now have a minor version of what you're seeing. From the front panel with the whole thing buttonted up, if I reach for the main "Tune" knob on the left side, the pitch does down a few cents, enough to beat against the A440 tuner. This primarily affects Oscillator #1 but makes it rough to tune the whole thing. Never noticed this before. I also extended the three thermistors from the oscillator board to sit on top of the transistor arrays with thermal paste and I'm wondering if I made a theremin antenna with that. Shielding the extension wires is the next test. Anyway, just wondering if you found an answer.