Oberheim Matrix 1000 repair

Hello! Acquired a non-working oberheim matrix 1000 unit at a swap meet.
Testing seems to indicate it is receiving midi signal, but no audio output.

The innards appear pretty pristine (no obvious melted or burned components), but there’s a pile of chips in here and I’m sure one or more of them are the culprit.

Any one have some advice?


Does is appear to be operating and you just get no sound, or does it not do anything? If the display comes up and you can change programs and such, then maybe the problem is with the output electronics. But if it is dead, then it may be a power supply issue.

it seems to be operating. display comes up, midi in light blinks.
do you know which chips are responsible for the output? admittedly not an electronics tech here, but I’ve been able to get a fair number of old keyboards back up on running…

If you can change programs and everything ‘looks’ normal, then I would start at the output end and work forward from there. Is the output jack good? If it is not obviously broken, then start looking at the op amps that feed it. That’s probably going to require an oscilloscope and some signal tracing.

I’ve been down this road. It’s likely a dead battery. If you’re trying to play on a patch between 000-199, those are the battery backed up patches, and if the battery has died, they all clear. Try playing a patch in the 200 or above range and see if you have sound. If you do, replace the dead battery and sysex dump in programs 0-199 afterwards.