Discussion about the Korg PolySix synthesizer

Hi Victor,

The sawtooth will be more a triangle, sorry. And it is very slow, so you
should set the oscilloscope to DC.
Check the following (with oscilloscope or DVM):
- IC20/pin12: you say it follows the PWM SPEED potentiometer
- the same but ca 0.6V higher should be at IC20/pin7
- again the same but this time 0.6V lower (than pin12) at IC20/pin8
- check that IC15/pin6 is the same as IC20/pin8
- IC15/pin5 is constant, please tell the value (about 3V)
- IC15/pin7 is constant as well, probably about 13.5V
The circuit is fairly simple there should not go wrong much ...

Johannes


On 13.02.2014 18:26, zc40@hotmail.com wrote:
>
>
> hello Johannews ,
> thank you very much, I measured the level Ic13 pin 1, the probe, and
> have in dc -5 to +5. That seems fine.
> The IC 20 pin 12 output. I see nothing in ac, but putting the selector
> in DC, I see -01 to -5 v that I can modulate PWM Speed \u200b\u200bpotentiometer.
> I do not see the waveform you told me to AC, I changed IC20, c32, ic 15.
> But still does not work.
>
> Victor
>
>
>