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
