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Sourcing Roland screws (Juno-106)
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Sourcing Roland screws (Juno-106)
The LT
Hi everyone,

Just saved two deader-than-dead Juno-106es from some local idiots who did not know that those were worth. One is lacking all 80017s and 5534s and has a broken bender. Another one fell victim to a bad DIYer. Lacks most of ceramic caps, has a few cut traces, fader shafts ripped from the faders, etc. etc.

Surprisingly, they are both in quite decent shape paintjob-wise, no dings or deep scratches, so after spending two days dismantling them and giving them a bath and a good polish to the keybeds, I decided that both are salvageable and decided to try and revive both units to original condition.

While I managed to source most of the common components like faders, op-amps and 80017s, I am having a hard time finding simple things like screws. One of them has most of the original screws but another one lacks half of them.

Does anyone happen to know someone who has some leftover from a Roland donor that left our world permanently?

Roland kinda kept the same screw models well into the 90s as far as I know. The panel screws are the same on my JP-8080 and VM-7200.

I know it's kinda OCD to bother with those screws but the stainless flatheads that are all over the place now are really causing nightmares and sleepless nights at the moment and I really want those beauties to be as close to factory-specs as possible.

Cheers, Guinness ftw!
unrecordings
I've got all sorts so might be able to help - can you post a photo of the ones you need ? - they're going to be japanned (black) M3 machine screws , right ?
Jaytee
There are a couple vintage synth repair Facebook groups that I would ask on. This forum leans heavily toward the building side of DIY and while I’m sure there are plenty of qualified techs/repairfolk here, it just doesn’t get much discussion. The Facebook groups, otoh, deal with detail-oriented repair topics like period-correct screws all the time.
devinw1
You can actually get flat heads in Stainless + Black Oxide finish. After you clean them in some alcohol, they will look a lot like the originals. It's not like black oxide on steel, but it's a little more shiny. The japanese do have a lot of special metal treatments that are propriatary, but if you can't find the ones you want, this might be a good route.

Here is a M3 flat head in SS with black oxide:

https://www.mcmaster.com/91698a300
The LT
Thanks for the tips, guys! Dropped unrecordings a PM so maybe he could help. You never know.

Unfortunately, I am a bit too old and paranoid for Facebooks and the like. But thanks anyways, I'll probably ask someone to look around.
unrecordings
I tried cross referencing your photo against the service manual but only managed to find references to four M3x12mm screws

Have a look through this and see if you can find the reference numbers to the screws you're after

https://syntaur.com/roland_juno.html

unrecordings
I've located a collection of likely screws - but understand that these are all salvaged from 30 years of dismantling bits of hi-fi & studio gear - so identifying the correct screws involves a bit of guesswork. Are the screws identified in yellow M3 ? So are the screws identified in red M4 ?

I don't mind sending a handful of these as a gift :-)
LektroiD
Most of the 106 screws are easily available new, I even managed to source some identical M3 mushroom-head screws for my Jupiter 6 panel. I'd much rather use brand new screws than chewed-up secondhand ones.

That said, I parted out a 106 a few years ago, I used some of the parts to refurb my current one, but still have a load of the screws. Also ask on my facebook group, "Synthesizer Spares or Repair".
unrecordings
LektroiD wrote:
I'd much rather use brand new screws than chewed-up secondhand ones.

The chewed up ones went in the bin years ago Dead Banana
The LT
LektroiD wrote:
Most of the 106 screws are easily available new, I even managed to source some identical M3 mushroom-head screws for my Jupiter 6 panel. I'd much rather use brand new screws than chewed-up secondhand ones.

That said, I parted out a 106 a few years ago, I used some of the parts to refurb my current one, but still have a load of the screws. Also ask on my facebook group, "Synthesizer Spares or Repair".


Oh, I had no problem sourcing the mushroom screws for my Jupiter-6 panels as well. Some guy specifically sold them on ebay. But the zinc internal screws turned out to be a pain to source locally. I remember them being in a lot of old juno synths. The short zinc ones are everywhere, even in the more modern gear. My VM-7200 and JP-8080 had those.

Anyways, I've bought a bunch of replacement boards and mostly managed to get what I need as they came with screws inside of them. I do really appreciate the willingness to help, guys!

The project is quite long and still going. I am trying to rebuild two units I've grabbed from local "artists".
The LT
Here is the full story for anyone interested.

I've recently got two Juno-106 from local classifieds. Both were sold as-is and surprisingly, both were quite okay cosmetically. No dents, no broken keys, no sticker labels.

One was used as a voice-chip donor. No black resin coated chips at all. It seemed like the owner tried to restore it but then decided to sell it off. It had all the original faders, but obviously cleaned and lubed, all the tact switches replaced and it looked like the keybed was given a bath and a rework. It also lacked a transformer and a power socket. The condition was quite nice, overall so I went with it. (The price was about USD 380$).

Another one was even nicer on the metal panel itself, although it had half of its faders missing its shafts (and caps, obviously). The faders were in a very bad condition, very grindy and dirty. Internal inspection showed a lot of missing generic components on all the boards and almost no replaced/new components. Not a single cap was replaced. It also showed signs of tampering with the boards and some "cut the trace, lift a leg" diagnostics being carried out by someone. The unit was lacking a mains fuse on the fuse board and torn mains wires. It looked bad.

Upon arriving home, I've discovered that the first unit had a broken bender assembly which was sloppily fixed by some foam linings. I wiggled it a few times and it came off. The bender pot itself was quite grindy and obviously resoldered as it had heatshrinked leads.

I've decided to start by trying to revive the first unit. I took the transformer out of the second unit and put it into the first one, checked the power board voltages and they were almost within specs. Adjusted VR1/VR2 and got +5/-15V going.

Then I decided to try and revive the chips from the second unit. The vca and dco chips on the unit were removed, acetone bathed and turned out to be in very poor condition. I've removed the SMD chips, did a thorough clean and resoldered them back in only to discover most BA226 chips dead. Also, 2 out of 3 DCO chips were bad too and I couldn't fix those. Out of 6 voice chips I've managed to salvage 3 along with one DCO. I've socketed the module board and put the chips in.

The synth came back to life, but patch memory was busted. The battery was replaced (dead for some reason) and a quick swap of TC40H000P did the trick. Loaded the factory patches in and now I have an almost working synth awaiting a replacement set of chips. I also swapped the bender assembly and pot from the second unit to it and the bender came back to life. Took me some time to fit it right though. Ordered a replacement bender part and pot from Syntaur and will rebuild the second one when the time comes.

Then I started to work on the second unit. It was totally dismantled and given a bath. Every key has been removed and cleaned. The rubber bushings were removed, cleaned with isopropyl alcohol and carefully put back together.

The panel board was overhauled with a new set of 16 new aftermarket faders and new tact switches and given a total joint reflow.

Then came the hard part. Closer inspection has shown that the unit was badly vivisected upon. A LOT of components were missing from every board. From what I could gather, the unit suffered a power malfunction as even the fuse board had a large blue ceramic cap torn from it and the mains fuse was nowhere to be found.

The power board check showed a faulty regulator, but that was the least of my worries.

The previous owner supposedly proceeded to "diagnose" the unit after a regulator fault by cutting traces, lifting CPU legs and tearing out ceramic capacitors on both the module and CPU boards. He even ripped out the blue ceramic resonators for some reason. Even the jack board is missing a few green capacitors and a couple of film (?) caps near the chorus circuit which I am still trying to figure out where to get.

I went with ordering what I could. Got a new CPU, a ton of ceramic caps, sockets and other parts and started populating stuff in. I also had to get a new transformer so I grabbed a set of transformer/fuse board/power board off Reverb. Turned out the new Power Board had problems on its own, unfortunately. The original power board had been messed with. Cut traces near the regulator, lifted traces near the transistors. You know. Ugly stuff.


The CPU board, while it looked very ugly at first, I've managed to fix by refitting all the ceramic caps back in, a couple of electrolytic ones, putting in a new ceramic resonator and installing a new NEC CPU to replace the 7811 mask ROM one. Socketed it in. Had to remove the resistor at J1 put a jumper on J2 to switch to external. Fitted a socket and put a 2764 EPROM with flashed binary in and boom, the thing works. I grabbed both NEC D7811G (with non-juno mask ROM for cheap) and D7810Gs for good measure. Both worked without any problems.
I still need to replace TC40H000P because I had to fit it to my other unit which is almost restored and required it for patch memory to work. Put a new battery holder in. The unit still had its seemingly original panasonic cell which still had 2.45V in it. smile The yellow band was as discolored as the ones I replaced in my Junos when I was a high school kid in the late 90s. But the CPU board works as tested in the first unit. Yay!

The struggle continues. I am sure I will have a lot of fun with the module board and the jack board. The module board was one big mess with almost EVERY ceramic cap RIPPED out. WHY? (Had to desolder and remove the leg remains). It also had both ceramic resonators cut out for some bizarre reason. I am putting money on the slave CPU being deader-than-dead too. It also has wrong value/casing type resistors hastily fitted near the voice chips for some reason. One of the "repairs" the guy did to his Juno. I would punch him but the seller said "I have no clue about what this synth is and what it does, sorry. AS IS!". Oh well. smile

That's the story so far. smile Need to tackle that damn PSU to move on.

Some pictures.

Unit 1 in the foreground, Unit 2 undergoing cleaning in the back.


Doing the chips.



Unit 2 cleaning in progress.





Some gnarly boards from Unit 2. Note the missing components.



Replaced the ceramic resonators. Notice the solder blob left by the previous "tech". That was a cut trace.


A patched-up Unit 1 near it's bigger brother, which is a whole different story in itself. Mr. Green It's fixed and taken care of though.
unrecordings
Fantastic work ! Good luck with finishing this project
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