Moog Polymoog

Well, I guess it’s time to post this. It was around 1979 when I was first getting interested in synthesizers that I first heard about the Polymoog. I always thought it was an interesting synth and a very cool looking keyboard so, of course, I always wanted one. A LOT! Well that day has finally arrived… sorta.

On Monday July 18, 2016 I won a Polymoog auction on ebay! At first I didn’t think I would try to win. I wanted to bid fairly low just as a weak try, just sort of symbolically I guess. But as the final hour approached I felt like it was time to get this off my chest and decided to bid high. The bidding was very quick in the last 15 seconds but in the end I won! I still haven’t figured this out, but I was, as usual, really nervous over the last 15 minutes or so. In fact, for most of the day I felt a bit sick with fear. I don’t know why auctions do that to me but they do.

And on July 17th it arrived!

And it was quite dead, as most Polymoogs tend to be! I knew that in advance and felt this would be a good project to learn a lot more about electronics and boy, was I right. It is now August 16th and I am still trying to trace down a few problems. Luckily I was able to get some sound out of it fairly quickly. After rebuilding the power supply I discovered a short in an old capacitor on the top right circuit board and quickly had that resolved. But there are a lot of other problems to deal with as well. Luckily the serial number is in the 4000s so it is one of the better, later model units.

At this point I have it mostly working but the remaining problems definitely need to be dealt with before I can put it back together and hear it for the first time in my studio. The biggest problem is the lack of decay and release in the loudness contour (envelope). I have a could of suspected chips in mind and will try replacing them soon.

Once I get that worked out I have to track down a strange glitch in the oscillators, get the VCF envelope working again (it worked briefly at one point), and then replace 4 dead divider chips. There may be a few more things to fix, I’m not sure yet, but those are the biggest problems and once they are resolved I hope to set it up… somewhere.. and get back to making music.

I’m also shooting video as I go and hope to do a complete video about the restoration so others can find information, the little I’ll have, to help with fixing their own Polymoogs.

I do have to say though that this instrument is nowhere near as bad as it’s reputation. There really isn’t as much electronics inside as I’d been lead to believe. Yes, there are 71 Polycom cards plugged into three motherboards (along with 3 balance cards that need to be in the right slots!) but they are not really a big concern and other than cleaning and reseating the cards and connectors they can be mostly ignored.

Other than those there are 3 large boards sitting over the motherboards, a master oscillator board on the back plugged into the divider board, and 2 front panel boards (3, counting the small board with the preset switches and the LED display). That’s it. It’s not nearly as bad as you would think based on the complaining you’ll find all over the internet. In fact, my Yamaha CS-40m which is also waiting for repair actually has significantly more electronics than the Polymoog and it is only duophonic!

So the journey continues! Hopefully I’ll get it working and find many uses for it in my music. There isn’t much left on my list. Maybe an Oberheim 4 voice, which would be VERY costly, or maybe a newer OB-6. But as usual, the thing I need most is time.