Roland JUNO-106 -1984    Weight=22 Lbs. Number mfg.=72,000 MRP=$1095

User Manual: Hinzen's
Reset Proceedures: N/A
Operating System code:
MIDI or other control protocol: VSE and Other tips
Software related Links: VSE
Patches or knob settings: VSE
Circuit Overview: below
Scematics/Service Manual: fdiskc archive or Hinzen's JUNO-106 manuals
Common Service Issues/Tips: below
Parts Sources: Keys knobs semiconductors misc
Uncommon chips/modules used: MC5534 DCO, 80017A filter module (containing IR3109 + BA662 I'm told- see below for replacement retro!), uPC1252, BA662 vca's, 5517APL 1Kx4SRAM chips (Have lots if anyone wants to make expanders!)
General Info Links:

Circuit Overview:
     A great digitally controlled 1DCO/voice 6 voice analog with patch storage and MIDI. MKS-7 is a preset rack version of sorts. The 80017A modules combine VCF and VCA for the channel. MC5534 module creates the digitally controlled waveshapes. I've never seen a diagram of one. Envelopes are also digitally generated. .

Service Tips:
     One of the major sonic strengths turns out to be a slight reliability weakness. The VCF/VCA modules go out. Sometimes it's a break inside from stress so be careful when installing or removing them! Earlier machines and 41C or 42B lot numbers of the 80017A module are known to be more failure prone. (Those were the numbers specifically mentioned in Roland's 1984 service bulletin saying replacement was the only option. Perhaps on some of those this was true but more recently we've discovered that softening the covering in acetone and just removing it after a day or two of soaking will repair a large percentage of faulty modules! It turns out a lot of problems were being caused by conductive crystals growing inside of the protective jacket it appears!) I personally have seen about half of the failures otherwise be in 47A lot but that's my personal experience. (oops 2 more in a keyboard I just got in today. Over half now.) In 2017 I did a unit with 53A's and all but 1 had an issue before I was done. 1 was broken in the mail and one had a wire come off when I removed covering. 2 failed and didn't respond to removal of covering. ) I also have a few 55A's that have gone out, a 55B, 43A and 4NA but I think most of those are usually pretty good. Take it for what it's worth of the half a dozen I've repaired or whatever. Nicely laid out with labelling on the board to figure out what is and isn't working right before the mix node.
     Other than common cleaning issues and a clock buffer that died on a couple, and one that had that and IC8 fail leading to a couple 8 note segments not responding AND a R/W line from memory chip where the trace failed (and saw someone else also had this issue the same week!) AND a 4.99k resistor go open making the VCF levels all change very little causing no sound to pass in the amp that is supposed to amplify instead of attenuate that signal :-) (poor guy from Indonesia sent it all the way here and it ate so many hours after the modules all failed... to get compensated I'd have to charge 450.00 or something at this point!! w/4 of my modules =240.00 plus more time than that....)
     ...Well, I worked on one today that had a scratchy volume control. I worked it over and swapped in a new one after trying a couple other entire modules I had. ALL were fairly scratchy and it sounded anyway more like a familiar phenomena involving some kind of bad ground design. Yet Grounds seemed good. Very strange. Always bumps some at the bottom of travel and gets noisier down near it.
     In the process I find there are TWO version of the bender board! And they are NOT pin compatable (portamento becomes the bender :-) ) One version has the plastic knob that matches the case. Other has more of the moog MG/opus type switch with aluminum shaft. Serial numbers were fairly close...'s actually the earlier synth that was having the problems of the three witht he moog type knob. Hmm. So I try swapping the jack board and sure enough the problem with the scatchy pot goes away. I'll try to research exactly *what* is causing that if I get a chance. Serial on the early one is 435534, and mine is 455827 and the one I scrapped is 494183. I see Roland made 72000. Mine has the later portamento switch and I'm looking at a unit 421646 which has earlier switch design AND has the pale green number buttons rather than the blue ones I have on mine. In another picture I see same on those two features. Probably the moog style ones were only on the first few thousand. Also note that the early ones may have EPROM on both boards whereas they used ROM mask in CPU on the later ones after they were convinced of the stability of the product to save some money in production. (PS Here is a table of Roland Serial number prefixes (first two digits til 1989 some month I believe)

Roland still stocks many parts for older instruments! You can always order them through your local Service Center and see what happens! Otherwise I have some parts also so don't hesitate to ask.
Contact Sound Doctorin'

RE: 80017A modules-

12/06 GOOD NEWS!!!! I've purchased and tested one of the 40 euro module redesigns. GREAT WORK! This should drive the price of the used modules down since these are way more reliable and sound identical! Here is the
Module Retro page. This device must be hard wired which takes a few minutes but well worth the effort to get something in using common 13700 ota's. Bear in mind that most modules can be repaired. Send them to me if you would like to give that a shot and I do have spare modules also for sale too!

If you try to troubleshoot these, it might help to know a few things re: the diagram in the manual. First the pin designations on BA662's are all wrong. 1=1 but what *they* say is '2' is really 3. 3 is really 4 is really 7, 5 = 8, 6 = 9, 7 = 11, 8 = 12 and 9 = 14. On both units. SECONDLY all resistors in between pins on the IR3109 are 68K and all resistors to ground (eg. from pin 2 are 560ohm or 550 they measure I see roughly. The two resistors by the left (in the diagram...right as you look at the actual circuit board in normal viewing with pins facing down) BA662 that go to ground are 1.5K and one of those attaches to a 5.1K to vcf in and the other to a 100K to vcf out (the feedback for resonance. ) Oh and the other resistor to vcf in is 3.9K. All caps are 250pf. The ba662 to the right in the diagram has a 47K in parallel w/ unknown cap value to gnd 2. The other two resistors to ground are 560 ohm measuring and from vca in there is a 4.7K resistor. Ok now the world knows :-) You'd think w/ a million of these units produced probably (70000 x 6 in 106 plus however many x 7 in MKS7 and however many x 6 in MKS30...) that an actual technical description would have existed before now? 8/6/2017

Midi Tips and a comparison of Juno-106 and Juno-60

Mike notes: I have had a few Juno106's and NEVER had aproblem with them. I always wanted a Juno 60 as they're supposed to be fatter and "punchier". I recently acquired one and so I decided to let my 106 go to someone who really wanted one. After I agreed to sell it I realized that the 106 has a higher ambience than that of the 60. Basically a string sound on the 60 with the "freq" at 10 would be equal to a "res" at 7 on the 106. The 60 didn't have the range I needed. It is fatter though as you can set the PWM of the OSC to the envelope.

     The Juno-106, for it's day, was extremely well thought out. Many of the machines from the time (eg. Siel DK600 or Sequential Six Trak) were very limited in MIDI capability.
Mike continues: You should mention that the Juno Librarian (off Vintage Synth) is a realtime live editor. Meaning you have instant axcess to thousands of patches. Once saved to the Library you can recall them instantly and the saved (computer) patch will overide the 106 patch. It can them be manipulated via the computer or Juno 106 and saved. Also, you can view the parameters of that particular sound on the computer, thus allowing for easier tweeking. This is how I discovered the issue (noted above) in the first place. I set all the parameters from the computer screen to the Juno 60. The sound semmed more "muffled" like it was in a pillow case.