Moog Music Forum

Hey all,

I just noticed a (hopefully) small issue with my Minimoog D, SN 5775: The oscillator 1 Pulse and square waveforms are not producing any output (the rightmost 3 waveforms on the rotary switch).

All other waveforms on all oscillators work fine. I can't remember if it was like this or not when I got it. The whole unit has been recently re-capped.

Any thoughts?

Thanks in advance!

There's a set of spacers for the voice card that keep it from shorting to the chassis at the top when installed. If the card shorted to the chassis when powered on, it can blow a transistor (don't remember which one, sorry) which kills the square wave output for oscillator 1.
Should be a fairly easy fix.

synthguy wrote:There's a set of spacers for the voice card that keep it from shorting to the chassis at the top when installed. If the card shorted to the chassis when powered on, it can blow a transistor (don't remember which one, sorry) which kills the square wave output for oscillator 1.
Should be a fairly easy fix.

Clarification: INSULATED spacers

I would also strongly suggest to check for proper contact on the two edge connectors on that board. Simply removing and re-inserting the oscillator board in those connectors could possibly resolve the issue. If not, remove the board again and check for any broken wires, or cracked solder joint, on the waveform selector switch for osc 1.
Most of the time, problems are caused by a mechanical/electrical fault, and not necessarly a failed electronic part.