Elektor Formant Modular

greetings - - 

im having trouble getting the old VCO to make any sound.

i noticed that there are 2 sets of power supply inputs on the back of the boards. on some of the modules i have these two have been linked together with cables on the boards them selves.  is this kosher, or does it really need a doubled up supply.

also the +5v had been soldered to the +15v bus board.  

is there a better way to do this? other things to try?

dont feel bad about suggesting any obvious things i might be missing. .  theres a good chance thats the case!!   im learning!

thanks,
brendan