Moog Music Forum

I switched on my Minimoog D today and noticed a problem with OSC 2. A very low frequency clicking sound - once every few seconds is all it sends out. Also, when moving the modulation wheel full up, I hear some faint output as well - at a higher more audible frequency. Is this a bad connection somewhere or just a dead component?

Update 7/2/15 Re-seated the OSC board and tried cleaning contacts - no luck. Looks pretty clean in there for a 30+ year old synth. Nothing looks burned out. I read a similar problem that was fixed with a replacement of the 741 component for OSC 2. Looks like I'm going to have to look for professional assistance here.

Thanks

Here's a photo of the board

All three of the Minimoog Model D's oscillators can be switched to sub harmonic frequencies ("down into the clicks"). Perhaps the octave switch on your second oscillator needs attention/repair to bring its output back into the audio range.

Thanks for the info. The problem just happened 'overnight' as in one moment it was working perfectly and the next, what it's doing now.

After reading of a similar problem from another owner, I thought I spend the 1.99 for a replacement 741 (ic4) and swap out the old one in the hope that this would work -which ended up not remedying the problem btw. Here is where it gets weird, though. After I replaced the board and started it up, I found that osc 3 was no longer working! Not long after, I was poking around checking the dc fuses just out of curiosity as to what they looked like and lo and behold, osc 3 decided to start working again! I am not by any stretch an electronics guy so, I would greatly appreciate any explanation of what exactly is happening here. Hopefully this would lead in some way to solving my osc 2 problem.

Thanks,
Norm

Almost always, that sort of spontaneous resolve is caused by bad or intermittent electrical contacts on the board connectors at the bottom.

Cleaning them invariably fixes issues.

I've found this to be the case as well. Looks like it's time to do some cleaning.

Thanks,
Norm

Well, after 2 years, 3 months and 25 days, I have a fully functional Minimoog again. It turned out to be a bad CA3046 ic. One side benefit is that in the process, I cleaned, checked and tightened up everything that needed it before finally getting to the real cause. There are a few loose ends that need attention, but it’s sure great to hear all 3 VCOs cranking away again