November 7, 2013
While researching vintage analog synthesizers I came across the Roland Juno 106, a six voice polyphonic synthesizer. I initially dismissed it as being something I would be interested in because it has digitally controlled oscillators and only one oscillator per voice. It does however have an analog signal path and traditional analog synth style control sliders. It's also one of the few analog synths to have midi. It's not as sought after (or expensive) as synths like the Jupiter 8 or Orberheims, but they do have a pretty loyal following.
I came across one for sale locally pretty cheap because it needed some work. They use a VCF/VCA module (one per voice, so also known as the "voice module") which tends to fail, so it's pretty common to find these for sale not fully functional. The module is a custom Roland circuit and obsolete now, but because a large number of 106's were sold and are still appreciated, there's a good deal of resources available for fixing them. I decided to pick it up for a fun little project and to get some hands-on experience with an actual analog synth to better understand what I was going for with my synth project.
One of the voice modules was obviously not functional at all and the previous owner had attempted to fix it without success.
A little more testing revealed that several other voice modules weren't operating 100% either. They exhibited the infamous "hanging note" - when a note is played and then released, the note can still be heard indefinitely instead of going silent. Originally the modules were encapsulated in some kind of epoxy or something. It's theorized that this is what leads to the failures so a common "cure" is to soak them in acetone to remove the epoxy. This treatment had already been done to all the modules but obviously it wasn't totally successful.
It's possible to track down original replacement modules but I decided to go with a modern replacement from Analogue Renaissance. This is basically a guy who reverse-engineered the original modules and came up with a replacement using modern components, so these replacements should be much more reliable and longer lasting than the originals, but have the same great sound. Considering the number of modules that had issues and the potential for future issues with the one or two that did seem to work OK, I decided to simply replace the complete set. Not cheap but IMO a worth while investment.
It also had the usual problems found in old keyboards - Dirty key contacts, bad tact switches and scratchy pots. Physically though, it was in quite nice condition, still had all the keys, buttons and slider caps, no cracks, chips, big dings or scratches. So I tore the thing down, removed the key bed to clean all the contacts, dismantled the sliders to clean them all out, and replaced all the tact switches.
Eventually got it all back together and calibrated and now it's playing beautifully. Initially I thought I might sell it after fixing it up, but after playing it, it didn't take long to start to understand why so many people still love this synth. It certainly has it's limitations, but it also has it's own character and wonderful sounds. It's not a substitute for my main synth project, but just might hang on to this thing after all.
I thought about doing a demo video of it, but a quick search on youtube brings up several really good demos, much better than what I could do.