> Try filtering the 10.3V supply some more, first....this sounds
> like (no pun intended) noise on the 10.3V supply, which is
> unregulated,
> and goes to both tthe CP and the audio amp.
>
Does 10.3Vdc (unreg) get tapped off the big filter cap on the
power-supply? If so, I did replace that. Didn't help in any noticeable
fashion. I haven't bothered to really look for the problem, but it
sounds just like a ground loop. Disconnecting the control seems to have
broken the loop (and fixed the hum). Maybe I'll look at it more this
week.
-Clay
