Hi Group! This might be a long shot but I need whatever clues I can get!

My matrix 6 behaves very strangely. When I play in octaves 2 and 3  the sound is mostly normal. But when playing in octaves 1, 4 or 5 the sound is very different. Sometimes there is no sound, just a 60hz hum. Some times the notes work but there is only 1 oscillator sounding. In the lower octaves when you play down from C2 the sound starts to get crackly and then disappears. 

BUT if I tune the oscillator up an octave then the low octaves work better. Not perfect, but better. It's a very strange problem and I'm just trying to understand the logic of what's happening so I can figure out how to fix it.

I've already reseated all the socketted chips (and cleaned the pins with DeOxit) and checked the voltages coming out of the power supply. I did a reset and several calibrations. No errors there or in tuning. I suspect it might be capacitors but it's strange that things work almost perfectly in octaves 2 and 3. Mostly it seems to be related to the keyboard but there are some minor problems within those 2 octaves as well. 

For example after the last calibration one voice started acting strange all across the keyboard (when it sounds at all). The filter envelope seems to work fine but after a second the sound completely cuts out, then half a second later it comes back.

Since something does happen when I play notes in those affected octaves I don't think it is the keyboard. I will check MIDI in and out and clean the keyboard contacts just to be sure but I don't think that is it.

I should also mention that when I got it there was no sound at all on any patch and I had to initialize a patch to get things working. So somehow all the saved patches got corrupted. Everything displayed on the screen looks fine.

I think recapping it is the next step even if it just to eliminate that possibility but any clues could be very helpful!

Thanks!

Scott