50 watt issue

[RHCPTIM]

Hello everyone, I came here hoping to gain some insight on an issue I just started having with my 50 watt kit which was assembled by metroamp. Anyway, the issue seems to be with the lead channel, whenever I turn it up past 2 I get a horrible high pitched squeal. My tubes seem ok. It does this even without anything plugged into the input. It only seems to happen with the lead channel. I've only had the thing for 2 months. Any help is appreciated. Thank you.


-Tim

[suede]

Check for a grounding issue. I had that same thing happen to me a long while back and found a bad ground on the buss that went to the on board filter cap.

[axeman]

Make sure the wires on the input jacks are not close to the wires coming off the pot's going to the board, especially the wire that connects both jacks of each channel.

Try That.

[neikeel]

If it is just on the lead channel over 2 it maybe a poor first stage filter cap - check the connections and the cap

[Star*Guitar]

Also I know you said the tubes looked good. But you could have a microphonic preamp tube. Tap each one with a pencil eraser and the one that rings the loudest swap out and see if it goes away. I once had a power tube go microphonic although I hear that is rare.