> ok i can try this as soon as i have a day with no function on the 126.
> could you please post a picture with the points marked where i
> have to test
> the vco

These are the only two pin headers that are equipped with jumpers: ST3 and
ST4. When the jumper is removed the left pin should output the
sine(ST3)/cosine(ST4). You find the position of the jumpers on our website
in the document that describes how to connect the external quadrature VCO
A-143-9: www.doepfer.com > PRODUCTS > A-100 > Module Overview > A-126 >
A126_A143_connection.pdf. The pin headers ST3 and ST4 are even used to
connect an external quadrature VCO.

Best wishes
Dieter Doepfer