"Ken" wrote in message
...
Brenda Ann wrote:
This thing's driving me to distraction...

For the longest time, I couldn't get the volume control to work (had been
out of the chassis, and I had no idea how to reinstall it) but I finally
have that working properly.

Now, I can't get the tone control to work. There's no change anywhere on
the control's excursion. It's an active control circuit. As of now, there
is a low level motorboat oscillation with the volume below about half
(~10 Hz).

If anyone has seen the circuit before, and can fill in any of the
unreadable parts, please do so.

TIA


If that's the tone control between the 6AV6 and 6BQ5, looks like a (neg?)
feedback circuit. If it got reversed somehow could cause motor boating.
Ken

Negative feedback circuit is OK.. if I switch the polarity, it howls like a
banshee..