Peavey Nashville 400

[rasater]

I have a Peavey Nashville 400 about 1985 or 1986 model that after anywhere from 3 to 15 minutes after being turned on emits a loud mid-range hum. To stop this hum I just tweak the mid-range control. I have looked for loose connections and shorts. Any advice? Thanks in advance.

[52 Bill]

Have you tried cleaning the pot?

[Enzo]

Next time it happens, ball up your fist and whack the top of the amp hard. Does that have any effect? In fact, even if it is working fine at the moment, whack it hard. Does that make it start humming? Hitting the amp helps expose loose connections.

ANd take Bill's suggestion, clean the control. And resolder the control, even if the solder LOOKS good.