
For a while it was okay. I was able to play normal, no sprite errors or something, just a normal behaviour without the sound. Then it became worse. It startet to boot only on the third, then on the fourth power on and so on. Now everything I get from it since some weeks is a garbled screen, regardless how often I power it up.
The garbage screen is never the same, it's always a different garbage picture every time I power it up, like this for example:

The amp gets warm (not hot, but warm), also I hear some noise (the sound reacts if I turn the +5V up or down).
BTW: When everything was kinda fine in the beginning, the pcb needed at least 5,2 volts to power up.
The Koyo quartz also gets warm.
Any ideas on this? Sadly most stuff on the pcb are custom chips...
