MOOG OPUS 3 CONTOUR HELP

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1

HI everyone - first post. I have a Sub 37 (love it) and I just picked up a refurb project - an Opus 3. I’ve opened her up, cleaned the foam, recapped the entire thing, cleaned the sliders, and swapped out a few of the IC’s (U2,U3,U5,U4,U11,U12,U19,U21,U22,U25,U26, IC1, AND ALL OF THE 4558 OP AMPS) hoping to get the VCF contour working, to no avail. Everything else works but the Contour amount slider - no audible change in that whatsoever. I have a hard time believing it’s the slider itself, but I 'm out of ideas. Any suggestions? Thanks in advance - Craig

2

Could be a hairline crack on a circuit track somewhere…?

Cheers,
Tom

3

Hi Tom,

Thanks for replying. I hadn’t thought of that. Which board would you think? The controller board, I assume?

Craig

4

Hello and welcome Craig !

First, make sure the slider is ok by measuring it whilst moving it. Second, it could be, as Tom suggested, a cracked PCB trace or soldering somewhere.

Alain.

5

Thanks! Bad slider…I never would have thought, but it looks like whomever owned this before me wore the thing out! I’m able to mess around with the filter now, though I need to get a couple of sliders and recalibrate the trimpot. It seems to go into a self oscillating type whistle a bit too easily. Very happy I’m able to get it going, and very thankful to both of you.

Best,
Craig