Juno 106 and Acetone

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EmptySet
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Juno 106 and Acetone

Post by EmptySet » Sun Mar 15, 2009 12:21 pm

I'm wondering if anyone else read the post this past week on matrixsynth describing a method for soaking bum Juno 106 chips in acetone to remove their resin coating and then magically making them functional again? I figured with news as potentially big as this, someone here would at least mention it. But I haven't seen it discussed.

Any opinions on the safety of this method? Why it would work? Why was the resin there in the first place? Could a handful of custom chip makers really be out of business via a quick trip to the hardware store?

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SickMonkey
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Re: Juno 106 and Acetone

Post by SickMonkey » Mon Mar 16, 2009 7:03 pm

IF it really works, I'm sure happy I bothered to remove all those chips properly (and save them), and not using the break-all-pins method recommended by some...

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Re: Juno 106 and Acetone

Post by Steve Jones » Wed Mar 18, 2009 8:16 am

The main problem internally is in one of the jump tracks going high resistance, I usually have to fix this once I open the chip. There are a couple of other internal faults that show up sometimes as well. If the problem is simply metal migration then opening the chip my make it better for a while, however opening the chip with acetone won't fix migration issues under the chips, it doesn't dissolve the coating, it only weakens it so that it can be peeled off, it won't get the compound out from beneath the surface mounts, and those modules do not take re-working very well. I have been opening and repairing them for years, sometimes just getting the coating off will help a bit, but usually there are issues in there that need to be addressed. Be careful putting the chips back in once they are open, there is more exposed metal at the base of the leads that can short tracks when you re-install the chip, so don't let them drop all the way down when you re-insert them.

No, this will not be putting the custom makers out of business, if they start working once you remove the encapsulation because they are running a bit cooler it is unlikely that it will be a long term recovery for the chip. If the problem is with the jump track and you fix it properly it will probably last longer, but if you really like your Juno and want to keep it, I would seriously look at buying the new modules for it. I have been putting some money aside to buy 6 for my machine, because then I will never have to worry about chips dying at just the wrong time.

I think that we are all pretty lucky that someone went to the trouble to make new subs for these chips, don't be afraid to support them, it's the kind of think that the vintage synth community needs, so lets encourage people to make subs for rare parts by giving them some support and thanks.
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Re: Juno 106 and Acetone

Post by Steve Jones » Thu Mar 19, 2009 11:09 am

With the capital A in Acetone in the title, this thread is a bit confusing, it sounds like new Roland and old Roland.
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EmptySet
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Re: Juno 106 and Acetone

Post by EmptySet » Fri Mar 20, 2009 10:54 pm

Steve Jones wrote:With the capital A in Acetone in the title, this thread is a bit confusing, it sounds like new Roland and old Roland.
Oops, sorry! I did it that way so it was like the title of a book. (title of post). I'm of course talking about OC(CH3)2.

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