Encouraged by the successful repair of the Matrix 6 I decided to disassemble the keyboard and try to get the non functioning keys working.
Inside the synthesizer I found some interesting things like some dead spiders and cobwebs.
After a close inspection of the keys I saw that they were really really dirty.
Check this out:
So, I wanted to remove all the keys and clean them. That took a while though. I had never removed keys from a keyboard before. Finally when I managed to remove them I gave them a good scrub and bath (actually) and left them to dry.
By the way, I guess this machine has been standing in a damp basement somewhere. Well, actually the guy I bought it from indeed said it had. That would explain all the cobwebs and dead spiders but I wasn't expecting to find rust in there:
I found some strange piece of metal with some strip of felt on it. It seemed to get compressed when you pressed a key down so I assume it's for the aftertouch.
Anyway, it was probably not working:
I resoldered that wire and cleaned the plastic around the felt strip. It probably doesn't matter but, well, I cleaned it anyway.
When looking at the circuit board where the keyboard triggers were I could see the problem causing the dead keys. It seemed as though the broken key really took a beating since it seemed to have cut down into the circuit board and severed the copper strips.
I checked the connetions between the right and left parts of the board and traced the tracks to check if it was where the damage was, and sure enough it was. So, I soldered some wires there to bypass the break.
For a while I was considering spraypainting the metal keyboard part to cover the rust stains but perhaps it's not needed. I just hope it won't fall apart after a couple of years...
I skipped the painting and cleaned the rubber contacts on the PCB and started to reassemble the board.
After assembling the machine I took a photo of the volume potentiometer hanging loosely inside :)
I didn't put the broken key back since I am going to try and glue it or buy a replacement for it. Now, in it's current state, the Matrix 6 looks like this:
After testing the unit again I discovered two keys were still not responding :( I guess I should have tested it properly before reassembling it but I was convinced the breaks in the copper strips on the PCB were the cause, and since I fixed that.. Well.. I guess I missed something.
Anyway, this is enough repairs for now I think.
I'll try to glue the cracked key like I said, and maybe get a replacement for the one that is completely broken.
Other than that I think I'll leave this machine alone and try to examine one of the other broken ones waiting for my attention...