Bricked JP-8000 synthesizer. Screen solid blocks No sound.

Forum for JP-8000/8080 synthesizers from 1990's

Bricked JP-8000 synthesizer. Screen solid blocks No sound.

Postby busssy2333 » 22:56, 5 October 2016

Got this synth cheap used with quite a lot of problems (LFOs going crazy by themselves etc etc). Brought it to a tech who fixed it but fixed for only about 5 months it worked %100, and he charged me almost more than a %100 functioning used one would have cost. I went to play it one day and the screen was solid lit up pixels and nothing at all happens, no sound etc. I can't access factory reset or anything. I never dropped it or anything. Replacing the battery did nothing. I'm not bringing it back to a tech. I'd rather sell it as-is for less of a loss. I already bought another JP-8000 (and a JP-8080 rack, and I think I'll get yet another JP-8000 as back up).

I fixed a few various synth problems in the past, mostly minor mechanical things though like stuck keys or the common pitch bend on JP-8000 not resetting to zero (on yet a different JP I had). I'm fairly confident in opening it up. Not much to loose at this point either.

I made some threads 2 years ago but never got around to tinkering with this. It has been recommended that I ask the Yahoo JP-8000 group, but there's been like 2 posts for the past 3 years and it's like all fake bots/spam now, a shame.

Some suggestions from previous threads were:

A link to this reddit of a similar bricked screen, ... up_please/

Someone suggested changing the screen but the person never followed up. Would changing the screen even fix this? Do you think I can just use a ~$2 HD44780 replacement LCD in place of the ~$60 JP screen.
The $60 ebay JP-8000 replacement screen says "Blue oled display suitable for a JP-8000, JP-8080." So since "suitable", maybe this person figured out the HD44780 works for it? I don't mind testing the HD44780 for $2 vs $60, I just don't want to fry anything!
This Used (therefore OEM genuine) JP screen does look different than the HD44780 though. I wouldn't mind silicone caulking the seal if that's all it needed though.
Used OEM:
the eBay one: ... 0&_sacat=0

The ebay one "suitable" shows in the last picture, it's different than the genuine used one also though. Also, the Ebay one has the ribbon already installed or is that just a snap on ribbon I can get for $2?

"I've fixed a Korg Mono/poly and two different guitar amps simply by opening them up and unplugging/replugging all the cables. Scratches the oxide off the contacts."

Should I start with this ^ first and use electronics connections cleaner spray (zero residue safe spray)?

" I would check to make sure any chips are seated properly then check the cables the battery and then look for bulging or leaking capacitors."

I know what a bulging capacitor looks like so I'll check that if I open to disconnect and reconnect all the cables and spray with electronics cleaner.

"Check all the power supply voltages. It may be that the +5V to the CPU is not working."

How do I do this!?^

"a bad battery I don't think will give you that best guess would be a dodgy capacitor maybe in the power supply circuit ...but it could be anything ....I would give this to a tech to figure out ...unless you want to open it up and check all the components visually and with a meter.... "
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