Thanks for your reply.

I made some tests with the scope yesterday night:

First thing I noticed is that rubbing with the scope's negative crocodile the main motherboard's ground, the digital noise tended to get higher in pitch to almost a pitched tone.

Even if I didn't test all of the  ICs, I noticed that the line Z18, Z28, Z30 had no pulse at their pins, only noise.

All changed after touching TP2 with the same probe, the noise totally stopped and I had the digital pulse back to those ICs pins. he problem now is that the synth is totally mute, even with the scratch patch.

Doing some diagnostics tests this morning, I found this:

D3= all lights on, but only when I'm holding the switch. As soon as I remove the finger the LEDs turn off (it wasn't like that)

D4=ADC Range, still I cannot turn on the LED while moving R45, but until I do not fix the A/D, I believe it is normal.

Many thanks!