Roland Jupiter 6 – calibration tips

Roland Jupiter 6
Roland Jupiter 6

The Jupiter 6 is one of Roland’s two most beloved 80’s polysynths, the other being the Jupiter 8. While I was looking for service documents for the Jupiter 6 though, I came across some absurdly aggressive forum posts from people who don’t like this synth and are pointlessly mad that a lot of other people like it a lot.

“Anyone who buys this synth is an idiot. It sucks your ugly fat mother’s balls and is only worth $100. You’re better off saving $6000 more and buying a Jupiter 8.” I like this synth, and I really don’t like the nasty and condescending vibes frequently given off by many (not all!) members of the online synth community, and its incessant undercurrent of crude misogyny. Maybe people (men) who frequent forums like Gearslutz (probably the worst) and Muffwiggler and CDM don’t notice this trend, because they definitely get super defensive and even counterproductively aggressive when anyone tries to mention it. Amazingly, people often try to deny that it happens at all. But as a woman in a subculture dominated by men, I notice it all the time and it always makes me cringe.  On Synthesizer Freaks on Facebook, I once saw someone who tried to bring it up (and his supporters) get hit with a torrent of sexist and homophobic insults, mixed with obviously-implausible denials, from dozens of people… and then a moderator deleted the whole thread.  I’m not going to use my synth repair blog to tell you all what to do, I’m just asking you to think about what you do.


Service Tips: This one had a SN in the 360000s and its module board was quite different from what was shown in the service manual available online.  This was especially important when it came time to calibrate it.  Here are some notes on test points and trimmer locations for this production model:

  • When you are doing filter calibrations, use the test point on the upper left corner of the module board that is labeled “OUT.” It works much better than using the main output as the service manual for the other versions suggests; the main output seems to have a lot of supersonic noise on it that will make it hard to read the scope.
  • This version has two resonance trimmers (instead of one in the previous version) that are used to adjust the X and Y offsets of the resonance curve; the Y is the one closer to the back of the synth, the X is just a couple inches below, both on the module board.
  • Use test points 2A and 2B for pulse waveform adjustments. They will be almost impossible to do from the output, as the manual once again suggests.
  • A lot of the voices’ circuitry are kind of dual versions (so hard-synced in pairs) in this version so there are only half as many trimmers for certain parameters, or even fewer for some things.
  • Also, I saw several posts from people saying that they were reading voltages like 3-4V on the DA offset test points (where it should be very close to 0 V) even though everything else seemed to be working normally.  I will admit that the reason I was reading these posts is that I myself was briefly confused. But the DA offset test points will not read 0V until you switch the synth over to test mode by moving the tiny switch on the center of the left edge of the CPU board to the “Jig” position, and THEN load program A1.  They do NOT read 0V normally.

Work Done: Just maintenance and calibration for the most part. Replaced PSU capacitors, heat sink compound, Roland power inlet replaced with IEC inlet, new patch memory battery. Found one bad diode messing up patch bank switching matrix. Calibrated to Roland’s specs.





14 thoughts on “Roland Jupiter 6 – calibration tips”

  1. I love my Jupiter-6 and I use it a lot. I have tried to understand the hatred it seems to draw – if I had to guess, I’d say the problem is that it is absolutely not an instant-gratification synth.

    The rich, beautiful tones lurking inside are just waiting to be discovered, but you won’t find them with the ham-fisted approach that is often very gratifying on other synths. The JP-6’s sweet spots are small but plentiful, so panel controls must be moved slowly and methodically as you make patches. The rewards are worth it!

    My JP-6 is plugged into a Mackle LM3204 line mixer, and I usually leave a little bass boost on it. The synth has great low end energy, but benefits from a bit of EQ. I think the MKS-80 Super Jupiter (which uses the same voice boards) has a bit of built-in bass boost on its final output, and it is renowned as a synth bass monster!

  2. I was fortunate enough to own a Jupiter-6 from the late 90’s to the early 2000’s and I loved it! It’s disheartening to hear that the JP-6 cops a beating in online forums; I found it be a very capable synth, from great string/pad sounds to rich and complex ambient soundscapes -a beautiful machine. It was such a joy to program as well – perfect for subtle sound creation (the presets never showed the true character of this synth). Probably should never have sold mine; they’re so expensive these days I’ll probably never be to afford a replacement!
    Love your blog, by the way – I’m working my way through reading each one of these very informative posts!

  3. Thanks for keeping the true spirit alive.
    I find this to be one of the most unique sound makers around, love the cross mod potential and as I have read and agree one should hear the beauty of the Jupiter 6 HPF and the BPF swept in all it’s sonic glory! (Unison mode try them all exp square and sweep own too)
    Hallelujah!may it be so!

    Love that you folks do Juno repairs too. I find the Juno and Jupiter are truly a match made in heaven as peculiar it may sound I mean Roland had a plan yes. What a mythos.

    And on that note so to speak I agree with you regarding female perspective on it all especially in audio. Male here though important to support the female voice and heck ya thanks for defending my righteous fav Jupiter 6. Wish you folks were closer to Ca. Rock on!

    Is it ok to plug a site that supports women in audio? They rock and so do you!

    1. Thanks for saying hi Jason! I do think Roland probably hoped everyone would buy both a Jupiter and a Juno, and that’s why they named them after a married couple. A match made in heaven, a match made on the Capitoline… the soft and pretty Juno 6/60/106 with the big and meaty Jupiter 8 or the keen and clever Jupiter 6 🙂

  4. Hi Alison,

    Thanks for this – I have a late-model board in this JP-6 on the bench here, and your notes saved me a ton of time and trouble!


    — Allie

  5. Hi Alison and everyone, my friend and I just did the Roland service manual adjustments on three (!) Jupiter-6 synths.

    We ended up stumped by step 2, the “DC Balance” adjustment. On each of the 3 synths, the trimmer seemed to have no effect that was visible on the scope, and the picture in the service manual is pretty vague. What should we expect to see here?

    On the first two, we did our best to just put the trimmer back to where it was. On the third synth we skipped the step entirely.

    1. Did you set your oscilloscope to DC mode? That calibration is needed to remove any DC offset from the final CEM3360 VCA that’s on each voice board, if your scope is in AC mode you won’t see the DC offset.

      Set your scope to DC mode, vertical scale to 1, 5 or 10 mV in order to have the biggest signal amplitude possible being shown on the display, and calibrate each voice board’s VR10 trimmer so that the white noise signal you’re seeing on the scope’s screen is centered around 0.

      1. First, thank you so much @mima85 for your quick reply.

        I did not set it to DC mode. The service manual (I guess erroneously) says it the scope should be in AC Coupling mode.

        It didn’t help that it was not my own scope, and I struggled a bit with its deep menu-driven method of getting around. I’ll definitely try to redo mine.

        After fixing it, will it knock out all the subsequent calibrations?

        1. You’re welcome.

          It shouldn’t knock out the other adjustments. It’s just the DC offset at the voice board’s final audio output VCA, which is after the voice’s own VCAs and shouldn’t have any effect on anything that’s behind it in the circuit. Eventually check again if the output level of the two voice boards still matches, just to be sure.

          1. After giving this a bit of thought: yeah I’m pretty sure the DC offsets are out of whack.

            As I said, the scope wasn’t mine, so I did struggle quite a bit to get triggering right. But I think with the DC offset as it was, it would only further exacerbate my attempts to get correct trigger levels.

            Interestingly, we did all the cutoff, res, and pulse width calibrations from the main output, and apart from the scope triggering annoyances they were all pretty easy, despite Alison’s suggestion to the contrary in the blog.

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