Korg Mono/Poly

hi folks,

I seem to have some problem with my Mono/Poly... I discovered last week that, when I hit any key, there is a white noise, even with all OSCs turned off... when the filter is all closed its still there, and also the VCA Envelope does affect the noise - when I turn the release up the noise sustains; So it seems like there is sth. wrong with the VCA or the VCF, no?

Do you have any hint where to look at first? is this probably a problem with the filter  ICs, or some capacitor in the VCA section??
I will record the noise today to demonstrate, if this would help?

best,
mark