High Pitch Squeel

[Stevie Joe]

What would cause a high pitch squeal when you turn the bright channel up past 9?
That is when I have nothing plugged in or when I plug in to the normal channel. When I'm plugged into the bright channel and turn it up it does not squeal past 9.

[Jazz P Bass]

Care to share what amplifier you are dealing with?
Is this issue something that just raised it's head?

[Stevie Joe]

It's a Mission kit 5e3. I never cranked it past 7 before this. It's only a few weeks old. Last week I put in 0.022 clipping caps in and forgot to take the jumper out and blew the 5y3gt. Got a new tube and now it works great till you crank it past 9 on the bright channel when plugged into the normal channel. Also when nothing is plugged in, and you turn the bright volume past 9 squeals LOUD. When it's plugged into the bright channel it does not do it.

[tubeswell]

You swapped the pre-amp tubes out/around?

[Jazz P Bass]

. Last week I put in 0.022 clipping caps in and forgot to take the jumper out and blew the 5y3gt. .

What are "clipping caps"?
As to the squeal, if tube substtution does not help, try reversing the output transformer plate leads.

[Stevie Joe]

The pre-amp tubes are working and in the right place. I will try switching them out with new ones.
I miss spelled it, I meant the coupling caps. there is two 0.047uf near the filter caps. and three 0.022uf next to them. I left the 22uf 50v in place. I will try reversing the OT plate leads now.
If the caps are raised off the board, would that cause the squeal? I left some leads long so it's easier to work on if I want to switch them out.

[Stevie Joe]

Switching the OT wires did not work. I also replaced the tubes. Still there.
What about the reflector tube, It's a 5R4GA. Just ordered a 5Y3GT.

[tubeswell]

Switching the plate leads won't make any difference in this case because there is no NFB in a 5E3 circuit.

[Stevie Joe]

Found the culprit that was making the squeal. It was the RG174 cable that was too long and too close to the inputs. Trimmed it up and now along with a few other wires that was too long and now it works like it should.
Changing out the coupling caps tamed the mud down to.

[pbiagi]

Hello Steve,
Glad you solved it.. I have a similar issue..
What is the RG174 cable??
Paul

[Stevie Joe]

Hello Steve,
Glad you solved it.. I have a similar issue..
What is the RG174 cable??
Paul

Hi Paul, The RG174 cable goes from pin2 of the 12AX7 to the right side post of the normal volume pot and the shield goes to the ground side on the same volume pot. Do not ground the cable on the tube socket side. Make sure you have a shrink rap on that side to the pin. The shilding on the pin side goes to nothing.