Recently I acquired a second Roland JP-8000 that actually was in like new condition, but it had a couple of output problems. The first was that the outputs L and R would no longer work, thus they were dead silent. In addition, the headphone jack would output a good signal but only up to level 6 or 7 and would then crackle or produce a loud distorted sound.
After some reading and research, I first changed the battery and did a memory reset. Nothing changed.
I then ordered and changed all of the OP AMPS on the Jack Board and Board B. Something changed! I now started to get output out of my L and R jacks but only to a level of 2 or 3. I also began getting some very bad distortion at higher levels that was very erratic. The OP AMP replacement seemed to have brought the jacks back to life but only to a point.
Thus I’m still faced with having a JP-8000 that doesn’t really produce any useable output. My next step is to replace the caps. I’ve read that replacing the caps on the Jack board didn’t fix much anything with others who had the same problem. However, I did find that if you change the caps on the Main Board, it does apparently fix the output distorted issue. I am now in search of the replacement caps as shown in the photo attached to the article.
It appears the Roland JP-8000 is one of those synths that is doomed to have some major failures as it ages. Not all synths are like this as some age better than others. I’d say pretty soon we’re going to see more Roland JP-8000 synths on the used market broken. Most likely they are going to have the distorted output problem. Note the JP-8080 rack version uses different caps and components than the JP-8000 which maybe is a hint that Roland knew the components used in the JP-8000 were not all that great. The Roland JP-8080 is pretty rock solid and I would recommend that over the JP-8000 if you are looking to invest in this particular synth.
In any event, once I make some progress on the Roland JP-8000, I’ll update this post. Also note that this again is my second Roland JP-8000. I have another in perfect working order which I may use to swap out boards to try and 100% isolate the problematic board. I did this with a couple of Roland Juno-2 synths I had which saved a huge amount of detective work. That certainly would help great in finding the problem with the distorted outputs on the JP-8000.
Stay tuned!!
Jim Atwood in Japan 