> Is the noise present only when a note is pressed and can you filter
> the noise   This can help locate at what point the noise is
> introduced.  Also, you say the notes ends with a Pacman sound  
> Have you a recording of this noise

Yes the sound is only present when a not is pressed and the sound can be filtered. Sorry the Korg is at the Technician's Lab so I am unable to record it. Think that the correct note comes out (with a lot of noise) during pressure of any key (all knobs like cutoff/resonance/envelopes/lfo working as it should) and the sound finishes with a "pacman" like sound. Noise is always there until the note is finish.