Matrix 6 Keyboard issue

So, some of the keys on my Matrix 6 are not working. There is a pattern to it so I suspect that it’s not just dirty contacts (and also I cleaned everything). I’ve been searching for a diagnosis but can’t seem to find anyone with a similar problem. Has anyone else experienced this or have any thoughts on how to fix it?

Since you have presumably eliminated the contact strips as a culprit, and you say there is a pattern to it, this can be either a problem with the voice circuitry, or with the keybed (i.e. either the key contact circuit board or the wiring to it). And the diagnosis below works for most keyboards - not just the Matrix 6.

If certain keys do not play - for instance if F4 (and other keys) never sound - then this indicates a keybed problem. I don’t recall the specifics of the Matrix 6, but a broken trace on the contact board or a broken wire will make a pattern of notes across the keybed that won’t play, like every 8th note or every 12th note as you play chromatically will not work, and those same keys will always not work.

Since the Matrix 6 is a 6-voice synth, if every sixth note does not sound, no matter what keys you play, then that indicates a problem with the circuitry on one of the voices. So if F4 doesn’t play one time, but then it plays fine a few notes later and now D5 doesn’t play, this indicates a problem with the voice circuitry.

Thanks for the reply Sam.

Every consecutive 8th and 9th note beginning with F#1 is not working. So, F#1>G1>D2>D#2.A#2>B2>F#3…etc.

Based on your reply, I’m guessing this is an issue with the keybed and not the voice circuitry?

Yes, that sounds like a keybed problem. And to verify that, plug another keyboard into the Matrix’s MIDI In, and verify that the Matrix plays fine from an external keyboard.

If it works fine that way, then the problem is either the key contact boards, or (hopefully) the ribbon cable that connects the keybed to the main board. Try unplugging and replugging this cable on both ends, and see if that helps (if there is oxidation on the connector pins, replugging can make a better connection). Also, check the cable itself to make sure that no wires have been cut or broken. If the cable is faulty, a replacement is here:

If the cable and the connections are good, then you’ll probably need to replace the contact boards:

Good luck, and please let us know the result!

Looks like someone spilled some Crystal Pepsi on the keyboard.

Definitely could be a damaged trace on that board. If you have a meter with a continuity tester (beeps when you have continuity), then you can test each trace from solder point to solder point and determine if one (or more) are faulty. If there is a broken trace, you can then use some wire to repair it - the easiest way is to jumper between the solder points.