Roland Juno-106 with Bad Voice Chip Restored

Back in November I wrote an article titled What is Your Favorite Poly Synth? discussing mostly vintage polyphonic synthesizers. One of them that kept coming up was the Roland Juno-106. Researching these popular synths, I found that they are fairly easy to come by, and usually reasonably priced. I found a great deal on one and snapped it up only to discover that it had the dreaded voice chip problem. Fortunately the seller agreed to refund part of the purchase price to help pay for the repairs. Six weeks later I have finally got it up and running, but it took some doing. Read on for more, and the the synth sound of the day.

The voice chip problem is caused by a coating that Roland used on the the chips that becomes conductive over time causing the chips to short. The coating can be removed by a process that involves soaking them in acetone for 24 hours. This process usually completely restores the functionality of the voice chips. I was prepared to have a go at this myself, but I found a service called the Synth Spa that does the restoration on all six of the chips, and calibrates the electronics (a process that requires an oscilloscope) for a very fair price.

The synth had some other problems that I repaired myself including a faulty power cable that I re-soldered, a broken plastic end piece that I replaced, and a broken potentiometer for the LFO delay time that I swapped out with a used replacement part. I purchased the parts from who shipped them to me lightning fast, via priority mail the same day I contacted them.

While waiting to receive the restored voice chips, I decided to do something about the decaying dust covers that go between the case and the multitude of sliders on the front panel. When removing the panel board from the case to replace the LFO delay time pot, the covers were all decayed and crumbling. I removed them all and replaced them with adhesive felts that I cut with an exacto to cover each and every individual slider. This was a lot of time consuming work, but it looks lovely and the sliders are now protected from dust by a layer of felt that will last for decades. Finally I buffed out a couple of cigarette burns on the keys, and gently tapped out a few dents in the chassie, leaving it in near mint condition. And it sounds great too. Here’s a short sequence I played and looped while adjusting various sliders.

Roland Juno-106 Restored

6 thoughts on “Roland Juno-106 with Bad Voice Chip Restored

  1. funny!

    “a broken potentiometer for the LFO delay time”
    same damned problem on mine, good to hear synthparts were solid.

  2. My old neighbor had a 106 collecting water damage in his basement. I begged him to give it to me but he wanted too much for it. Most of the sliders were broken and the memory was shot but the few sounds I could make out of it were so cool! I ♥ the square wave.

  3. @trainspotter You should go for it if you still have it. It’s a fairly easy fix. Getting the panel board out can be a bit tricky, but swapping the pot was a minor, soldering affair.

  4. @john, i probably will its kind of funny you get a pro-one i get a pro-one shortly after. i get a juno 106 then you get a 106 haha both needing repair.. are you in mpls?

  5. Hello mate!

    I’m trying to make the chorus circuit work, but I needed to know what voltage reading should I expect at left of R51? (according to the service manual)

    Also, what voltage should I expect at left of R2??


Leave a Reply