The signal to the output and the headphone share a common signal path from the effects board KLM-368 via CN15 pin 3. As you say it only causes a problem with signal out I'd be looking for a problem with bad solder joints, dodgy output socket connections etc on klm-369. Look closely around R1,2,3 and 10 also CN7 pins 4 and 5. Also check that the output level sw is in good order.
--- In PolySix@yahoogroups.com, "Ells" <ellsounds@...> wrote:
>
> Hey all,
>
> My Polysix just recently developed a symptom where patches with a good deal of resonance get quite noisy. It's like a white noise generator. Only seems to be when the resonance is cranked up above 6 or 7 and it's only from the main output (headphone jack displays no problem).
>
> It also hasn't been totally consistent. Once recently I powered up the synth and it was normal.
>
> I've had the battery replaced and traces repaired about 7 years ago (minor damage as the battery had just barely begun to corrode). Plus she's MIDIed up with the Kenton kit. So I've put a lot money into the old girl and can probably live with this issue as otherwise she's fine and I can turn down the Q if need be. Or just say my P6 now has a noise generator!
>
> Anyone else have this or a similar problem and was it a relatively simple repair or a mainboard issue?
>
> Thanks in advance,
>
> Ells
>