Hi,
No problem Florian, you already did a lot to help me find what causes the issue. It seems that I have to give it for service in order to be checked further. Portamento potentiometer seems to work fine.

Maybe a TL chip is defective or something goes wrong to line from this pot to VCO4.

I will give it for service next weeks and I will let you know when I have the results.

Thank you very much

--- In korg_mono-poly@yahoogroups.com , Florian Anwander <fanwander@...> wrote:
>
> Hello
>
> > All four measures seem to be the same:
> Hmm. Now I have no further idea where to look for. Sorry.
>
> Florian
>