Elektor Formant Modular

Hi,
i´m Wolfgang and i´m just building, or should i say repairing an old
formant (elektor book). i have some problems, cause the earlier owner 
who has build the synth, hasn´t done it very well, and i must search a 
lot of errors. maybe you could hepl me a bit.
I have two questions at the moment. The keyboard, which was also in the 
elektor book, has a output voltage (KOV) around 4V, when there is no 
key pressed, is that normal ? I can adjust the voltage when the lowest 
key is pressed, to O Volt. But after releasing this key, i goes up to 
4V. When the keyboard is not connected to the modules, the VCO led 
(which also show´s the PW) lights.. Should it light ?? ..cause i have 
a low frequency output at the VCO out, even when i switch to ECV, and 
nothing is connected .. Is that normal or an error ? I can´t find 
anything in the book about that. Thanks for any help appreciated. The 
rest so far works, except the 24dB filter, but i will do that later. 
First i try to manage the VCO.

Sorry for my bad english...