Juno 106 - Original voice chips work, should I strip?

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Juno 106 - Original voice chips work, should I strip?

Postby bertmacklineFBI » Mon Jun 18, 2018 4:28 pm

The title says it all. I've done as much digging around on the internet as I can to try and find the answer about what the best course of action is for my (new to me) Juno 106 that somehow has six working OEM voice chips inside of it. I'm an avid DIYer and have no fear of the desoldering, acetone stripping, and socketing the chips.

I got a steal on eBay because it would "cut out sometimes but the problem happened randomly between the chips", turned out the H/M/L switch need a little DeOxit and the problem was solved.

There are four schools of thought I've found on why the chips fail:

  1. The most commonly referenced issue is that over time the epoxy coating becomes conductive and shorts out traces and components on the chip. While this may be true, after deep digging I found an individual who took his epoxy coating off of a malfunctioning chip and then tested it with a multimeter and found it wasn't even remotely conductive.
  2. A second less talked about theory is that the epoxy is supposed to help conduct heat away from the chip, or distribute heat evenly across the chip, and is not very effective, and the cheap construction and painted-on traces on the chip eventually succumb to the contracting/expanding and break
  3. The third school of thought is that the epoxy coating was just for IP protection (like the goop on a Klon Centaur) and it's cheap, resulting in either issue 1 or issue 2
  4. The fourth has nothing to do with the epoxy and is that the pins on the chip are cheap and poorly attached and eventually can't properly conduct between the board and the chip.
  5. It could be any combination of any of the above :)


This makes it slightly harder to move forward. If the issue was unanimously that the epoxy becomes conductive, and Roland only added it for IP protection, then obviously removing it would secure the future function of the chips. But if the epoxy has any other function, such as thermal conduction, removing the epoxy won't prolong the life of the chip, or may actually damage it. There's a lot of folks out there, however, who have the epoxy removed and the chips work great for extended periods of time - maybe what the epoxy is actually losing over time is its thermal conductivity, and the open air inside the Juno is a better cooling solution.

Ok, that's enough of my inane ramblings. What does Vintage Synth think?
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Re: Juno 106 - Original voice chips work, should I strip?

Postby Mooger5 » Tue Jun 19, 2018 12:39 am

IMHO nr.5

If all the chips are NOS and still work faultlessly, then that was some lucky find. I say leave itt at that. Resist the urge to tinker.
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Re: Juno 106 - Original voice chips work, should I strip?

Postby madtheory » Tue Jun 19, 2018 8:53 am

Agreed. If it's not broken, don't fix it.
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Re: Juno 106 - Original voice chips work, should I strip?

Postby bertmacklineFBI » Tue Jun 19, 2018 3:46 pm

Mooger5 wrote:IMHO nr.5

If all the chips are NOS and still work faultlessly, then that was some lucky find. I say leave itt at that. Resist the urge to tinker.


But I LOVE to tinker haha. Alright, this is the resounding advice I keep getting. If they still work, maybe they will keep working and don't touch them. Thanks!
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