Discussion about the Korg PolySix synthesizer

Cutoff VCF CN5-13 gives  7.43V  | -7.37V

                     I18-14 gives -3.56V |   3.64V 

Power supply readings on CN2 pins are all fine.

Yash

Better to measure at IC7-7.    After IC18-14 there
is an RC filter and then a unity gain voltage follower/buffer.
You can measure at IC7-7 without disturbing the voltage.

How do you know these value are incorrect?   What were you
expecting?  I will measure mine later and see what I get at CN05-13. 

Bob

What should the values be at I7-7?

Yash

Hi Josh,

    Here is what I measure (poly, manual)

Cutoff Ctl at 10:   IC7-7 = 4.91      IC8-1=  -7.36V
Cutoff at 0:           IC7-1 = -4.98     IC8-1 = 7.49

   I would suggest making the earlier measurement after the buffer.
Your meter may be loading down the voltage.   Anyway, the important
voltage is the one that's later in the circuit, and here our numbers are
very close.

    It seems your expected values were spot on, within circuit tolerances.

     Bob

Oops!   Should be IC7-1     Sorry about the typo.

  Bob