Matrix 6 is alive!

Great news!
A couple of days ago I received the rotary potentiometer I wanted to use as a replacement for the volume slider. I had some problems soldering it to the board (because all the copper was gone from the copper islands) but managed to solder it anyway by scraping the protective coating from the copper tracks and pulling solder from there. I didn't pull the wire through the slider slit (didn't want to have to resolder it if I wanted the pot mounted on the inside later) but just let the pot lay around on the inside. The front panel seems to be able to rest in the closed position without cutting the wires to the pot though, so I can keep it laying around outside by the two levers to left of the keyboard when it's powered on until I decide where to attach it.

After my modification was done I felt tired and was going to go to bed, thinking that a replaced volume slider probably wouldn't make the thing come alive but for some reason I just wanted to power it on and try before I went to sleep.
So, I connected the mains power lead, switched the Matrix 6 on...
LEDs light up and I see a preset name in the display window! What? It was completely dead before I changed this. I can't really see how it would prevent startup.
I plugged some headphones in and noticed that the jack was kind of loose and felt like it was going to fall off on the inside any second. Will have to check that.
I got sound! I tested the volume control and it seemed to work. I had used a log pot and the volume was almost silent until about halfway, perhaps the pot should be tapered backwards or I should use a lin pot? Anyway, it was working.

I played around a bit and found some more problems:
Some of the keys didn't respond.
However, the key that is broken in half was working, but the key to the left of it wasn't :) Also the cracked key to the far right was also responding. Other than that the dead keys seemed to be randomly placed. Some white, some black.

Another big concern was that one voice didn't make any sound either :(
However, I recall my Matrix 1000 had a problem where one of the oscillators in a voice would stop working above a certain frequency. I had run the calibration procedure just as a test to see if it helped the Matrix 1000 voice and it had worked so all the voices were working. Would the calibration bring back the completely dead voice? I found the way to do it in some PDF manual and let the calibration run... No errors were reported during calibration. Hm? I played a bit.
All six voices working! Yay!

So, now I have a previously dead 117V Matrix 6 with a busted volume slider that I have at least changed to run on 230V with a "working" volume control and all six voices are working fine!

Last thing I did that night was to turn it off, unplug the power cord and put my finger on the heat-sink for the voltage regulators. Ouch! I couldn't keep my finger on it for even a second. The voltage regulators are too hot! If some semiconductor is to hot that you can't keep your finger on it for even a second it probably means something is wrong. That is worrying me a lot so I will have to look into it. Perhaps there's a short somewhere or one of the regulators is bad and is heating the whole thing up? I'll have to investigate. But still, great news! It really lifted my mood.
I'm going to remove the "out of order" status of this synthesizer :)