Dario:
If i'll understand that this is the reason of my problems, how could I solve it?
If this is it, you would need some kind of power conditioner or stabilizer. You could try taking your H8000 to another building, which would presumably have a different power situation, and see if it does the same thing.
Dario:
the red led hasn't never been highlighted
I meant that your input signal should occasionally light the red led.
One other thing – I assume that you have the clock (sync) source set to "internal".
