Today I had another session with m matrix 6: played for one hour, more or less, then the issue reappeared. So, the culript could be a slowly but inesorably IC going too hot...
I have just bought a new 68B09 cpu from a chinese seller: in one month time it will be at my place and I will replace the old processor and all the caps on the cpu board, just in case. Let's see if this will be sufficient.
Any help would be much appreciated (is anyone still reading me :) )
Thanks!