Members ElectricPuppy Posted June 8, 2009 Author Members Share Posted June 8, 2009 I had some time this afternoon so I removed ALL of the epoxied modules and they're all soaking in The Treatment right now. I've got some silicone conformal coating waiting in the wings to recoat them with once they're clean. Link to comment Share on other sites More sharing options...
Members The Hamburglar Posted June 8, 2009 Members Share Posted June 8, 2009 Fascinating thread. Anyone have any advice / suggestions of further reading on this sort of thing / electronic circuitry / electrical engineering / etc., especially as pertaining to analog synths? Link to comment Share on other sites More sharing options...
Members ElectricPuppy Posted June 8, 2009 Author Members Share Posted June 8, 2009 I'm not an electrical engineer, I just play one on TV. But, if you're really interested in electronics, my advice is to start small and if you can, find a mentor. I haven't had anyone to bounce questions off of, so everything I know has come at the cost of time and frustration. (I've been playing with this stuff since I was a kid, literally.) And I STILL don't know half of what I would like.For books, I recommend the Forrest Mimms "engineer's notebooks" from Radio Shack (yes really). I learned a LOT from those long ago. Get some parts and pieces, follow the exercises. Good test equipment will save you a lot of grief and confusion. Another good book is "The Art of Electronics"; it's not weighed-down with too much math, although a good grasp of algebra, trig and logarithms is a big help.One thing I find enlightening is looking at schematics for synth modules and stuff. There's a Synth DIY mailing list, and the Electro Music forum (www.electro-music.com) is chock-full of fascinating stuff. You might consider getting a MFOS kit (http://www.musicfromouterspace.com/), he seems to have some pretty cool stuff, from starter-level on up.Overall, I guess I'm saying that there's no quick route to analog electronics mastery; I'm still trying to get there myself after over 30 years. It's one of those things that you can spend a lifetime learning. Link to comment Share on other sites More sharing options...
Members The Hamburglar Posted June 8, 2009 Members Share Posted June 8, 2009 I definitely understand that it's a long, never-finished journey, thanks for pointing me in the right direction. Link to comment Share on other sites More sharing options...
Members ElectricPuppy Posted June 11, 2009 Author Members Share Posted June 11, 2009 So I may have, uh, gone too far with The Treatment. (uh oh.) I dumped the oscillator modules into the acetone bath as well, since I already had one fail and suspect it might be epoxy-related. When I pulled them out of the bath yesterday, I discovered that those modules had an additional lump of epoxy under the overall module epoxy. That tells me that the chips on these modules are unpackaged dies, probably with very delicate wires connecting them to the surrounding module. This epoxy had started to lift, too, to the point where I don't think it would be a good idea to leave it on now.What Im concerned about is how ingrained the pad wires are in this epoxy and if it'll dissolve enough to let go without yanking the wires with it. Yikes. So, I'm committed now; I put em back in the acetone in the hopes that those lumps let go gently. If not, I've got 3 dead oscillator modules on my hands. Link to comment Share on other sites More sharing options...
Members kpatz Posted June 11, 2009 Members Share Posted June 11, 2009 Error!... oscillator module disassemble... reassemble! Link to comment Share on other sites More sharing options...
Members ElectricPuppy Posted June 13, 2009 Author Members Share Posted June 13, 2009 Link to comment Share on other sites More sharing options...
Members ChristianRock Posted June 13, 2009 Members Share Posted June 13, 2009 Well are they all working now? Link to comment Share on other sites More sharing options...
Members deadvolvo1 Posted June 13, 2009 Members Share Posted June 13, 2009 This thread absolutely kicks ass.I have a Juno that's got one of the 80017a clones in it, and the clone doesn't behave the way the real deal does, unless you warm it up for about an hour. Even then, it doesn't like high filter resonance.Still have the "bad" voice chip, and I will attempt this procedure soon.Great work, EP!! :thu: Link to comment Share on other sites More sharing options...
Members kazper Posted June 14, 2009 Members Share Posted June 14, 2009 I wouldn't sweat it yet, but I would look at installing some millmax pins on the pcb's and place sockets on the mobo so they can be pulled out quickly. (looks like that may not be a option from the pict's) My pro one that I had when I took it apart I had a CEM chip just hanging by it's little hair thick wires... and it still worked.. I just wanted to see if I had J wires or not.. Link to comment Share on other sites More sharing options...
Members ElectricPuppy Posted June 14, 2009 Author Members Share Posted June 14, 2009 Well are they all working now?I don't know yet. Those pics are prior to spraying them all with silicone conformal coating, hence the masked-off pins. The stuff should be plenty dry tonight and I can install them tomorrow and find out! Link to comment Share on other sites More sharing options...
Members ElectricPuppy Posted June 14, 2009 Author Members Share Posted June 14, 2009 Update:The coating on the modules is cured (150 F in the oven for 30 min) and they're reinstalled in the Juno. All voices work except #3. Some poking around with the scope shows that the VCA section is out on that module. Perhaps I was a bit too zealous on that one when I was picking out bits of leftover epoxy, maybe I scratched a trace on the ceramic, I don't know.ugh.At least this shows that I (generally) can't hurt the modules with this technique, so I'm going to process the remaining backup modules. I think, though, that I'll only do this with the VCF modules and leave the wave modules alone.I don't know now if it's possible to bring the dead VCA on #3 back to life or not, so I think I'll just write this module off. So, a few more days of waiting for acetone to do its job on the remaining backups and then I'll try again. Link to comment Share on other sites More sharing options...
Members ChristianRock Posted June 15, 2009 Members Share Posted June 15, 2009 ElectricPuppy has come to save your Junos!!!!!! Link to comment Share on other sites More sharing options...
Members ElectricPuppy Posted June 17, 2009 Author Members Share Posted June 17, 2009 eYou guys tired of this yet? I discovered something interesting today; I removed the epoxy from the remaining 5 VCF modules I have on hand, and it turns out that one of them is different. Underneath the epoxy, the module is covered in what appears to be the same stuff that covers the IC's on the wave modules:The epoxy sheets above and below came off of that module, note the lot number, "61A". This was the only module I have in that lot, and it makes me think that my donor Juno got it as a replacement earlier on. The higher number makes me think that Roland at some point decided that the modules needed additional protection than just the epoxy dip alone.It's ripe for speculation. I didn't notice beforehand, but this is also telegraphed through the epoxy. Notice how the outlines of the components underneath is much less defined than the other modules, as shown to the right.I'm wondering how well this lot has held up over the years as compared to the others and if they're any less prone to failure?Anyway, I'm going to install this one as the replacement for failed #3 in my Juno as-is, no additional coating, and see how it fares over time. I wish I had known about the extra protection on this module before, or I would have left it alone as an experiment. Link to comment Share on other sites More sharing options...
Members deadvolvo1 Posted June 17, 2009 Members Share Posted June 17, 2009 Very interested to find out more about this lot number, 61A. I propose all KSS Juno 106 owners (practically all of us) unite in a common purpose to document our 80017a's and related failures. A little data collection from each of us, when put together, can wind up being very useful for all of us beleaguered by failed Juno voices. Link to comment Share on other sites More sharing options...
Members elmacaco Posted June 17, 2009 Members Share Posted June 17, 2009 with the one that you have the bad VCA, maybe try resoldering the pins on the IC's, they could have been removed from the pad and hard to see. Just heat with an iron, maybe a tad of solder. Link to comment Share on other sites More sharing options...
Members ElectricPuppy Posted June 17, 2009 Author Members Share Posted June 17, 2009 Thanks Elmacaco, there's a good chance that that's what happend; When I was picking bits of resin out of my second batch, the VCA on one of them lifted off on one side! As long as it was halfway off, I went ahead and removed it entirely because a) I wanted to measure the resistors that are buried under it, and b) to see how far the resin reached underneath.The resin must have been pretty thin, because it completely covered the bottom of the chip and there was scant space between it and the ceramic. That means that there's still resin underneath all these chips and I wonder if it'll cause a problem later.Also, for the record: The pinouts shown for the BA662 used as a VCA in the diagram of the module in the service manual are wrong.Overall, I think the REAL solution to these module is to remove the resin, salvage the chips from the them (making sure all resin is removed) and then reinstall them on new carrier boards using new SMD resistors and caps. That's a lot of trouble to go undertake, though. Buying the clone modules is probably a much better use of time and money. Link to comment Share on other sites More sharing options...
Members deadvolvo1 Posted June 18, 2009 Members Share Posted June 18, 2009 EP, my experience with the clones has not been 100% satisfactory. Even after re-calibrating the 106, the clone voice still behaves differently than the others. It was very hard to get it in line with the originals, and I have to warm the synth up for nearly an hour to get reliable/cooperative results from the clone voice. The main problem is resonance. When the resonance is set above a certain level, that voice will go out until you either lower the resonance or boost the cutoff frequency to max. It will then come back. This happens less and less over the course of an hour after power-up. The method which you have demonstrated seems like it will at the very least reduce the likelihood of future failures, and may be enough to revive most if not all the problematic modules, for the time being. I would say in most cases this is enough. Link to comment Share on other sites More sharing options...
Members kazper Posted June 18, 2009 Members Share Posted June 18, 2009 EP, my experience with the clones has not been 100% satisfactory. Even after re-calibrating the 106, the clone voice still behaves differently than the others. It was very hard to get it in line with the originals, and I have to warm the synth up for nearly an hour to get reliable/cooperative results from the clone voice. The main problem is resonance. When the resonance is set above a certain level, that voice will go out until you either lower the resonance or boost the cutoff frequency to max. It will then come back. This happens less and less over the course of an hour after power-up. The method which you have demonstrated seems like it will at the very least reduce the likelihood of future failures, and may be enough to revive most if not all the problematic modules, for the time being. I would say in most cases this is enough. Which module were you using? Link to comment Share on other sites More sharing options...
Members kazper Posted June 18, 2009 Members Share Posted June 18, 2009 Thanks Elmacaco, there's a good chance that that's what happend; When I was picking bits of resin out of my second batch, the VCA on one of them lifted off on one side! As long as it was halfway off, I went ahead and removed it entirely because a) I wanted to measure the resistors that are buried under it, and b) to see how far the resin reached underneath. The resin must have been pretty thin, because it completely covered the bottom of the chip and there was scant space between it and the ceramic. That means that there's still resin underneath all these chips and I wonder if it'll cause a problem later. Also, for the record: The pinouts shown for the BA662 used as a VCA in the diagram of the module in the service manual are wrong. Overall, I think the REAL solution to these module is to remove the resin, salvage the chips from the them (making sure all resin is removed) and then reinstall them on new carrier boards using new SMD resistors and caps. That's a lot of trouble to go undertake, though. Buying the clone modules is probably a much better use of time and money. Yes and no... you could do a mixed through hole etc... the pcb's would be dirt cheap in reasonable quanitys and you could make them drop in with mill max pins. Link to comment Share on other sites More sharing options...
Members ElectricPuppy Posted June 18, 2009 Author Members Share Posted June 18, 2009 The 3 chips and 5 caps on here are already SMD, so may as well remain in the SMD domain, eh? The thing that has me a bit worried is how the exposed printed resistors will withstand moisture over time.I wouldn't use the socket pins if I thought the board was going to be gigged, I'd be afraid of them working loose. Link to comment Share on other sites More sharing options...
Members deadvolvo1 Posted June 18, 2009 Members Share Posted June 18, 2009 Which module were you using? AR's clone, I believe 5th generation. Purchased July 2007. No disrespect at all to the effort and expertise (far and above my own) that went into creating a nearly perfect clone. But....Despite an experienced tech following the directions to a T, my result was not what I had hoped. Link to comment Share on other sites More sharing options...
Members idiotboy Posted June 18, 2009 Members Share Posted June 18, 2009 teh puppeh: you're mad. Mad I tell you!! Link to comment Share on other sites More sharing options...
Members ElectricPuppy Posted June 26, 2009 Author Members Share Posted June 26, 2009 Update: I've got felt that I'm going to use for replacement dust shields, and I'm waiting for delivery of a tube of dielectric silicone grease so I can give the sliders a thorough servicing.I should probably reinstall the voice board, though, and make sure all the voices are still working before embarking on that. Next weekend. Link to comment Share on other sites More sharing options...
Members ElectricPuppy Posted July 3, 2009 Author Members Share Posted July 3, 2009 Update: All voices are working, even after a long warm-up, although some adjustments need to be made (slight popping on note on/off on at least one voice). I've got the grease now, so tomorrow I plan to: a) backup the patches and replace the battery; b) remove, clean, lube and reinstall all the sliders; c) Replace the disintegrated dust shields with either felt or new black foam (haven't decided which). ... and then I'll have a fully armed and operational battle station. Yay! Link to comment Share on other sites More sharing options...
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