This Roland JP8000 repair was to resolve an issue with a distorting output. After being in storage it transpired that there was an issue with the output stage upon testing it. The main output was much quieter than usual and there was a degree of nasty distortion, rendering it unusable. The headphone socket did not have the drop in gain, however, it did have intermittent distortion on it.
I was not happy about having to fault find on the board but fortunately, a web search led me to a page where other people had exactly the same issue. It turns out that this rather common on a JP8000 of this age. This meant my search was narrowed down straight away, and this saved me a few hours of fault finding time. Unfortunately it was not as simple as the Korg MS2000 repair I did recently.
On the plus side, all the other controls seemed to work except for one button used for selecting patches. This had failed a long time ago, and I was aware of the problem. I had previously bought the part to fit. It was simply a case of opening this up and getting to work on finding the culprit.
JP8000 repair – Capacitor 219
It turns out that it was the main capacitor on the output board that was causing the problem. This is designated as capacitor 219. I also changed out the rest of the capacitors on the logic board as I was getting some strange readings on many of them. The button was easy to replace, and in all it was nice to work on. It was even more pleasing to restore it to its former glory, and now it is serviced ready to go on for another twenty years.
In this video I diagnose some faults, show you how to solder new electrolytic capacitors on to the board, and test switches to ensure proper operation.