Thanks, I’ve been absorbed in this for hours now! Looks like exactly what I needed.

Hey all, I was wondering if anybody might have any recommendations or pointers towards a way to gain a little more familiarity with the type of digital systems typically found in the vintage analog polysynths like the OB-Xa. I don’t usually have much issue troubleshooting the analog sections, but I ...

Thanks! The actual original problem ended up being on an op-amp socket I had soldered in- seems the input and output of the amp had bridged together with solder from my sloppy work.. So a good reminder to myself and anybody reading to always check the simple things as well, and well, be less sloppy ...

Turns out not long after replacing q6, a12 which I had already tried swapping started to smoke! Replaced it and now it's good! Just a few more little problems here and there..

Here is the related schematic- A14 is the amp I referred to

Ok, so over the past few weeks I've been wrapping my head around this broke down Polymoog keyboard of mine best I can. Just trying to understand the signal flow and getting a general idea of what's happening has been a chore all on it's own given the complexity it is famous for. Anyway, now I've got...

I've got this Model D which is missing several components, and I've not been able to find some of them at all. I breathed a sigh of relief when Moog announced the new Model D, but alas, they won't deal with me at all. Anyway, I'm looking for: -the prop in the rear that holds up the panel. Would real...

I remember a far simpler mod working on the Moog Prodigy, not sure if it's the same. Anyway, there was a pin in the pitch wheel that kept the wheel from spinning too far that can be removed. This allowed it be be tuned a full octave lower, probably could have worked for higher too, I forgot by now. ...

Davolisint on Caravan's "The Dog, The Dog, He's at it again"
Roland System 100 all over the first two Human League albums
OB-X from Rush's "Subdivisions"

Good call on R12! I pulled it, and measured it, and it was conducting nothing whatsoever. Replaced it, and back to new

My OB-Xa and I thank you very much Broadwave!!

Hey all, I'm experiencing a small, (usually tougher to figure aren't they?) but annoying problem with my OB-Xa. One voice card has a problem with VCO 1. I have moved the card around, it is certainly only on one board, one VCO, problem follows the card. Anyway, the problem is an unsteady, and too low...

Vox Continental and Hammond L-100, couldn't do without them!

Ic202 in the keyboard circuit looks like a good potential starting point

Got it! Found a first edition manual pdf that had a procedure for matching the upper and lower voices portamento time with some trimmers

Hey everybody! I recently refurbished my OB-Xa (bushings, caps, etc.) and just completed calibration. Only problem is my Obie is a very early model with the analog portamento, and well, the portamento is severely out of spec. Some voices are a good bit slower than others on max portamento, probably ...