Synth doctor part 1: The tale of the Juno 106S and the dead voice chip

Last summer I started what I suspect to be a lifelong synth collecting habit, when I bought a 1984 Juno 106S off a gruff man with a Kasabian hairdo in Leicester.

It’s part synthesiser, part time machine; the sounds it makes are quintessential 80s: think Tears for Fears, Pet Shop Boys, New Order. Basically my ultimate party playlist. It sounds so. beautiful.

But the problem with old things? They break. I switched on my Juno one day last November, and found that one of the voices was no longer working. For context: this particular synth has six ‘voices’, so when one breaks, it means that every 6th note you play is silent. It’s beyond infuriating.

On conducting a Google search on the problem, I found myself tumbling down the rabbit hole of vintage synth repairs; it’s a world of sprawling forum threads, shakily filmed youtube how-tos, elusive eBay hunts, and a handful of shadowy figures with the tools and know-how needed to keep these beautiful instruments on the road.

Maybe you’ve stumbled across this page because you’re down the same rabbit hole – that being the case, read on. And that not being the case, you might find some nuggets anyway. It’s my first exploration right down into the wires and circuitboards which power the music I love – I’ve learned so much already, and have a feeling there’s much more to come.

Step by step – How I’ve troubleshooted (troubleshot?) my Juno’s dead voice chip

  1. Which voice chip has died? For this, you’ll need to hold down the ‘Key transpose’ button as you switch the Juno on. You can then run through the 6 chips and see which one is having issues. Number 1 was my troublemaker.
  2. Open it up! All you need is a screwdriver, and maybe a cheeky allen key. This step also made for some excellent father-daughter bonding when he was down to visit last weekend. And you get to see beneath the Juno bonnet in all its glory…

    Inside a Juno 106S
  3. Take a look at the voice board. That’s the one on the bottom left there, with 6 proud standing voice chips.
  4. There’s a lot of chat online about soaking the voice chips in acetone and then scraping off their resin coating to fix the problem. I found there was one main thing stopping the laywoman carrying this out: the voice chips tend to be soldered in, which means you need a desoldering iron, or clumsier desoldering braid to get it out. And on soldering it back in… I could feel the Juno quaking with fear at my very limited skill in that department (one year 7 DT class). But all these considerations turned out to null and void, because when I uncovered my own voice board, I found someone had been a-scraping already.20180225_132222
  5. So, I was out of ideas and it was time to bring in the pros. I got in touch with Conor Caulfield, a veteran synth repair guy based out near Wembley. He has a delightful habit of starting each email with a brand new title. Screen Shot 2018-03-03 at 21.58.29 Drop me a message if you’d like his contact details.
  6. He suggested first to check that the connectors hadn’t oxidised, by spraying some Isopropyl Alcohol (IPA for short) into the female connectors, and to work the male connectors up and down as they were reinserted. Sigh. Top naming conventions by electricians of old there. For the fellow beginners out there, this what a connector looks like: 20180225_121803 (1).jpgBut despite my best working-up-and-down, my voice chip was still silent.

Part 1 ends with my trekking through a blizzard to Conor’s synth repair shed, voice board bubble wrapped in my bag. Loupe in one hand, rollie in the other, Conor eyeballed the voice board and declared – Voice chips: Scraped. Soldering: Competent. So, it seems 95% certain that nothing short of a new voice chip will do.

He taught me how to judge the quality of the chips from images online. At the top you have ‘New Old Stock‘, ie the real deal from the 80s, through to already-scraped affairs (to varying degrees of meticulousness), through to people trying to home-manufacture new voice chips from scratch. He scrutinised the pin width and length, the scraping efforts, everything to a minute level of detail, as that’s what can ultimately make the difference.

I opted for the New Old Stock, and it’s in the post from Spain now.  And that’s your cliffhanger… part 2 coming as soon as my chip arrives and the snow thaws.


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