Roland MKS-80 Super Jupiter Repair

I recently purchased a Roland MKS-80 in need of repair. Several things were wrong with it including the tuning knob, dynamics slider and “insert cartridge” errors when trying to change the patches from the front panel. Without being able to tune the synth or utilize the dynamics, the instrument was effectively unusable, but I decided to buy it anyway in the hope that it could be repaired. After several days and more than thirty hours of research, parts swapping, and troubleshooting I managed to get it working properly. Read on for an illustrated story of the repair process and audio from the fixed unit.

Estimates for repair were rather high, so before handing it off to a technician I decided to see if I could manage the job myself. This was a far more technical challenge than I had ever attempted and it didn’t go well at the start. The first step involved swapping out a an integrated circuit per the advice of a local synthesizer repair tech. The IC was an eight pin dual comparator. I removed it and put in a socket for the new chip, then replaced it with an equivalent component. Unfortunately this had no effect. I studied the circuit diagram with a friend who suggested that it could be caused by a second IC. This time it was a dual operational amplifier, also eight pins. Once again, I socketed the PCB after removal to make it easier to try other ICs and once again, no change occurred in the operation of the device.

I needed to go back to the drawing board. Although I had successfully metered the potentiometers for the dynamics slider and the tune knob, I decided to take a closer look at the panel board based on a suggestion from the technician at the Synth Spa, a specialty synthesizer repair service that operates via eBay. The panel board looked fine, but during another test I noticed that if I pressed down firmly on the dynamics slider that the pitch would change slightly. Further testing showed that if I held down the dynamics slider I could tune the instrument with the tune knob. This led me to suspect that there was a dry solder joint on the slider. Another clue was that the dynamics slider was bent, perhaps from a fall or hard knock. I heated up the joints and applied new solder, but not only did the original problem persist, but I could no longer press down on the slider and hear the pitch change.

This was frustrating to say the least. I was ready to give up and hand it off to someone more qualified than myself. Instead, convinced that the dynamics slider had to have something to do with it, I pressed on, removing the slider from the panel board and testing it again. It worked as expected. All that was left to try was to reinstall the slider and hope for the best, but during the re-installation I noticed that the solder would not stick to the top pin. I got up close to the PCB and looked carefully at the pin hole and saw that the metal track around it was gone. The panel board had been damaged by whatever caused the bend in the dynamics slider and when I removed it the cracked metal track must have come off the PCB with the slider.

Now that I suspected what the problem was I attempted to make a repair. The top pin of the dynamics slider went to two other locations on the PCB; pin one on the tune knob, and the first pin in the socket that connected to the CPU board. I cut a length of wire that would reach from the tune knob to the dynamics slider and finally to the socket. I stripped the wire on the ends and remove a small piece of insulation from the middle of the lead. I attached the middle of the wire to the top pin on the dynamics slider and then attached the ends to the tune knob pin and the appropriate pin on the CPU board socket. I secured the lead in place with some solder and tested the instrument one more time. Finally it worked! The repair is a bit of a hack, but easier than trying to find a replacement panel board. Here’s a sample of what I’ve been producing with it.

Roland MKS-80 Fixed

20 thoughts on “Roland MKS-80 Super Jupiter Repair

  1. Having heard this piece firsthand I have to say the hard work is completely worth it. Nice work!

  2. Cheers, Kyle! It probably reads as if I were miserable the whole time, but I really enjoyed the process of being neck deep in the guts of the thing. I learned a ton and will be a little less intimidated next time I take on a similar project.

  3. It’s actually amazing how many times cracked or crumbling solder joints are the problem. I used to think components were always the first suspect, now the first thing I do for any repair is put on a some 3x reading glasses an examine damn near every joint.

  4. That is my usual route, but I was duped! The joints looked fine, the volt meter confirmed it… what I should have done was test with the meter the joints before and after the offending pin. Ah well… hindsight. :P

  5. Wonderful 16 oscillator glory! I’m assuming the MKS-80 was a rack mount version of the Jupiter 8?

  6. A lot of people compare it to the Jupiter 8. There are a lot of differences and a lot of similarities. Although I’ve never laid my hands on a Jupiter 8, in some ways I think I’d prefer the MKS-80, because of the as velocity sensitivity and… MIDI! However, the JP8 is legendary and MIDI and velocity do not a good synth make (read

  7. Can’t wait to hear where this piece leads. A victory track!

    Your walk through reminds me of my repairs I did for my plasma TV. The value in DIY and sharing the story.

  8. I’ve just purchased a MKS 80 and it has the “insert cartridge” problem. Without the cartridge when choosing Int it says “insert cartridge” but when the cartridge is there the synth chooses bank B when the switch is at Int.

    How did you solve the “insert cartridge” problem on your synth?
    Can you give me any advise? Feel free to email me.

  9. Hi, Lukas. I have not completely solved the insert cartridge problem. Once the synth has been on for several hours it goes away, but not always. I can always get to the internal sounds using a MIDI controller. For example bank C on my Roland D-50 changes the internal patches while the problem is happening. My work-around is to send program change data from two empty clips using follow actions in Ableton. One of the clips changes the patch as if the problem is happening (bank C), while the other changes them as if it is NOT happening. That way, in a live performance setting, it always works.

  10. Thanks for the reply (and that you emailed me)!

    I use an old Roland D-5 as my midicontroller. I’ll experiment with it and see if I can change bank in a similar way you do. Otherwise I’ll try one of my other synths as a midi controller for the unit. I use Cubase on my computer and I would like to not always start the program and send a program change message for it to work, but it’s good to know that it’s possible. I don’t use the MKS 80 live as I’m a little scared something goes wrong with it. It’s an expensive synth…

    I’ll go try this out now. Thanks again!!

  11. Couldn’t change to bank Int with my D-5. Even tried it with my XP-50 and JX 8P. With the JX I could get at some of the sounds on the Int bank but not all.

    So I tried with Program Change in Cubase instead. That worked but only when set the switch to bank B and used program change numbers 64 and upward. According to the manual you can get at the internal memory this way through program change. When I edit a sound in the internal memory and write to the internal memory (I of course set the memory protect to off) it doesn’t remember the new sound when I switch sounds and go back to it.

  12. Another test. Took out the cartridge, set the sitch to bank B, used program change to get to internal bank, edited a sound again and tried to save the tone and now it says “insert cartridge”.

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  14. Thanks for detailing your repair process. I just bought an MKS80 and has the same problem as yours, so I’m hoping it’s the same issue. Thanks again!

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