Discussion about the Korg PolySix synthesizer

At 08:10 AM 10/7/2005, you wrote:

>So is this what makes the Polysix have DCO's?

Eh, not exactly...


>Today I checked the resonance voltage at CN05-7 and found out it's
>rastered, because I couldn't set it to exact 0V. It jumped in about
>50-60mV steps, no matter how carefully I turned the knob.
>
>Is that a result of the signals going through the CPU?

OK, I was giving a simplified answer.  To be more exact, on a memory type 
synth, all CVs are multiplexed & turned into digital information;  this 
information is then demultiplexed & turned back into analog voltages to 
feed the various synth functions (this is best understood by looking at the 
CPU page of the schematics).  This may seem  like a cumbersome way of doing 
things, but it's what allows the synth to memorize & store control settings.

The point was that ANY problem with the digital circuitry (CPU, CPU 
support, DAC, ADC, etc) can cause problems or non-function in the analog 
synth circuits.  If you don't have a scope (or at least a logic probe) to 
look at the various data and address lines, repairing a PolySix can be a 
lengthy & difficult proposition.
Normally, most problems with the P6 have to do with shorted, distorted or 
missing data or address lines, which totally bugger the audio circuitry.

~GMM