When I started working on it, this JX-3P looked like a feral synthesizer that had lived in the forest. It was rusty, the legends had been scraped off in many places, the plywood bottom piece was rotting requiring it to be held together with tape, and it was spattered with literal mud. It had also been subjected to one of the strangest DIY repair attempts I’ve seen yet. Someone tried to overcome some bad key contacts by squirting some of that yellow expanding spray foam insulation stuff into the tops of a few of the rubber key contact strips. Guess what… it didn’t work.
I got a nice pair of before and after *synth makeover* photos out of this one.
By the way – I strongly believe that this is a better synth than the Juno-106, and the interface is really not so bad. But I’m not going to get into why right now.
Service Tips: Some people seem to think the switches on these are irredeemable if they go bad but I managed to save all 21 bad ones that this synth had. I removed them, soaked them in isopropyl alcohol for a few days, let them dry, and then dribbled a tiny drop of DeOxit D100 down the little crevice where the metal switch contact on each one was. After a few presses they were all back to normal. I use the D100 in the nail polish-type bottle because it’s better for working on tiny things like this.
Cleaned and/or repaired 22 malfunctioning key contacts, and 21 malfunctioning button switches, replaced 11 bad key springs. Deconstructed/cleaned sliders and replaced one broken slider. Replaced power supply capacitors and patch memory battery. Replaced plywood bottom piece of synth. Installed IEC inlet to replace built-in power cable. Painted rusted areas. Cleaned everything, a lot.