Roland JX-8P Synthesizer

The one I found was a little road worn. It had one dead key, another couple of keys that were sluggish, and the volume slider needs some help (it only goes to 1/4 volume or to 11). Even with the dead key it can still be controlled fully via MIDI – which is how I normally control these synths anyway. And, when I record, the volume is cranked to send the most signal through the lines. So, a couple pretty easy fixes which aren’t even a priority for me.

Parts of this machine are pretty worn so I might do some custom work to it. I normally avoid doing major cosmetic changes but anything I do to this thing will be an improvement at this point. Perhaps a total paint job – Bright Red! I’m not sure yet. I need to crack it and see how the guts look first.

She’s a tired old girl but she sounds good – and the aftertouch actually still works. (shock!)


The guts of the JX-8P

The guts - location of battery. The Roland JX-8P uses a soldered on BR2032. There is plenty of room to replace the soldered on battery with a BR2032 battery holder.

More JX-8P guts

The top of the keyboard and a row of springs.

The underside of the keyboard. I had this machine apart to fix a dead key.

The key switches are pretty simple and easy to access. They are just a series of thin copper strips which contact when the key is pressed.

The dead key on this machine had the bottom copper contact bent out of shape. It took about 30 seconds to tweak it back in order.

The underside of the JX-8P keyboard

An interesting thing for those with a JX-8P with dead keys – when I put this back together I caught the underside of the keyboard on my shirt or something. I didn’t notice right away but I bent a few of the T-shaped contacts inside with the other contacts.

When I reassembled the keyboard and tested it, all the keys from these bent contacts no longer worked. It also stopped all the keys up from this section. It was simple to pop the T contacts back out and put them back in shape.

Something to keep in mind if you have a chunk of keys which don’t work on a JX-8P.

Insert fantabuliousy specs..
Polyphony – 6 voices
Oscillators – 2 DCO’s per voice (12 oscillators)
Memory – 64 patches + External memory cartridges
Effects – Portamento
VCF – standard VCF
VCA – ADSR envelope
Arpeg/Seq – None
Keyboard – 61 note keyboard with velocity and aftertouch
Control – MIDI In/Out/thru
Date Produced – 1985

Acquired: 2009

3 comments to Roland JX-8P Synthesizer

  • Jim Atwood  says:

    Great job Peter!

    I recently acquired a Roland JX-8P. Everything works great except I get stuck notes when I hit several keys, primarily the black ones. The notes just sustain and when I attempt to hit them again they don’t don’t sound obviously because they are sustaining. When I attach a keyboard controller, I can play without any issue at all. The JX-8P is perfect!! Thus no problems when using a controller keyboard. Key bed has been cleaned. Aftertouch works great! I just can’t get rid of the sustained notes. I’ve heard this is a big problem with the JX-8P and there doesn’t appear to be a fix. Any ideas?

  • Jim Atwood  says:

    Sorry! I mixed emails and wrote the wrong name in my previous comment. Content still applies. I can’t seem to figure out what is causing all of these sustained notes ont he Roland JX-8P. It must be somewhere in the contacts, but they all look great. Thanks!!

  • dave franklin  says:

    How did you fix the volume? I am having the exact same problem

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