Hum/Squealing from 5E3 Deluxe Build

[zeppy3]

Hey, I recently built a 5E3 Deluxe copy using the Fender Schematic, which in the beginning turned out to be great and sounded wonderful. I had to redo a few things a couple of times because of laziness while soldering, but now whenever I play through the amp, I get a significant amount of hum. Also, when there is nothing plugged into the amplifier and I turn up the volume controls on either channel, I get a loud high-pitched squeal from the speaker.

The speaker is a Jensen 12" Mod
The power tubes are 6L6s
The preamp tubes are 12AU7s.
The rectifier is a 5Y3

I've tried different sets of 6L6 tubes and other preamp tubes, including 12AX7s and 12T7s and neither reduce the hum. I've also tried a 5U4 rectifier which didn't do anything either.
If you are able to help that would be greatly appreciated.

[TD_Madden]

swap the wires on pin 3 of each output tube with each other?

Try with the correct preamp tubes and output tubes (12Ay7, 12Ax7, 2x6V6)?

[tubeswell]

swap the wires on pin 3 of each output tube with each other?

Hi TD

How does that work on a 5E3 (where there is no GFB loop)? (I thought squealing that could be cured by swapping the OT primaries was related to positive feedback - caused by having the GFB loop off the "wrong" side of the OT sec, which swapping the primaries would thenceforth rectify. But I stand to be corrected)

I was wondering whether the problem in this instance might be caused by bad soldering (if the problem occurred after the OP re-soldered something)

Cheers

[zeppy3]

Hey thanks for the posts. I connected the input jacks directly to ground, which seems to have fixed the problem and I still get volume through the speaker. The input jacks I'm using are from an old Gibson amp from the sixties, so I'm not so sure they're very good anyway.

[Bruce / Mission Amps]

Hi TD

How does that work on a 5E3 (where there is no GFB loop)? (I thought squealing that could be cured by swapping the OT primaries was related to positive feedback - caused by having the GFB loop off the "wrong" side of the OT sec, which swapping the primaries would thenceforth rectify. But I stand to be corrected)

I was wondering whether the problem in this instance might be caused by bad soldering (if the problem occurred after the OP re-soldered something)

Cheers

Sometimes when an amp is built up by a novice, the lead dress leaves "something" to be desired and there is too much capacitive coupling that is similar to NFB and reversing the OT primary leads seems to cure it.... yes, rare.

[loudthud]

You say you used the "Fender Schematic". Did you ground one side of the heater (6.3V) supply and connect to the chassis at each tube socket?