Roland Juno-106 with Bad Voice Chip Restored

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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 SynthParts.com 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

This entry was posted in One Synthesizer Sound Every Day, Synth DIY and tagged , , by John CS Keston. Bookmark the permalink.

About John CS Keston

John CS Keston is an award winning transdisciplinary artist reimagining how music, video art, and computer science intersect. His work both questions and embraces his backgrounds in music technology, software development, and improvisation leading him toward unconventional compositions that convey a spirit of discovery and exploration through the use of graphic scores, chance and generative techniques, analog and digital synthesis, experimental sound design, signal processing, and acoustic piano. Performers are empowered to use their phonomnesis, or sonic imaginations, while contributing to his collaborative work. Originally from the United Kingdom, John currently resides in Minneapolis, Minnesota where he is a professor of Digital Media Arts at the University of St Thomas. He founded the sound design resource, AudioCookbook.org, where you will find articles and documentation about his projects and research. John has spoken, performed, or exhibited original work at New Interfaces for Musical Expression (NIME 2022), the International Computer Music Conference (ICMC 2022), the International Digital Media Arts Conference (iDMAa 2022), International Sound in Science Technology and the Arts (ISSTA 2017-2019), Northern Spark (2011-2017), the Weisman Art Museum, the Montreal Jazz Festival, the Walker Art Center, the Minnesota Institute of Art, the Eyeo Festival, INST-INT, Echofluxx (Prague), and Moogfest. He produced and performed in the piece Instant Cinema: Teleportation Platform X, a featured project at Northern Spark 2013. He composed and performed the music for In Habit: Life in Patterns (2012) and Words to Dead Lips (2011) in collaboration with the dance company Aniccha Arts. In 2017 he was commissioned by the Walker Art Center to compose music for former Merce Cunningham dancers during the Common Time performance series. His music appears in The Jeffrey Dahmer Files (2012) and he composed the music for the short Familiar Pavement (2015). He has appeared on more than a dozen albums including two solo albums on UnearthedMusic.com.

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.

  5. @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?

  6. 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??

    CheerS!

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