This video, via Exploring Audio, takes a look at identifying and fixing voice chip issues with the Roland Juno-106 synthesizer.
If you’ve done similar repairs with keyboard voice chips, share your experience with this in the comments!
The most common problem with Juno 106’s is the voice chips suddenly dying. The chips were just not meant to be used for 30+ years. Apparently, the coating that Roland used on these chips will begin to conduct electricity and this causes issues the voice chips. Removing this coating will fix this issue and extend the lifespan of the chips! This doesn’t work in all cases and I strongly recommend doing outside research before opening your Juno up but it does seem to fix the issue the majority of the time.
I strongly recommend watching Syntegrator’s Juno 106 videos. Most of this video is heavily based on the information he presents there and before you ever open a Juno, check out his stuff first!