More 5F1 Champ Build problems...this one is strange

[Bruce / Mission Amps]

These amps are about the easiest amps to build in the history of amps... ha ha

You aren't running isolation washers on your input jacks are you?
Does it blow anything with just the power tube removed?
With no power applied, not plugged in to the wall... what is the DC resistance as measured from the 6V6 socket, lug 8 to ground?
Are you sure your 220K resistor is grounded?

The jacks, although wired unconventionally, look right to me.

With the rectifier in but no 6V6 or 12AX7 in.... what are the voltages on all the tube socket lugs?
Do the same thing with just the rectifier and 12AX7 installed.

(Just making sure you don't accidentally have B+ to the wrong lug somehow)
Ya know you could just have a bad 6V6 tube too.

[MWJB]

Hum - your plate wires (pin 3 6V6, pin 6 12ax7) run very close to the green heater wires, as do the grid wires (6V6 pin 5 & 12AX7 pin 7) this is a recipe for hum. Pull out/rewire the green heater wires so that they either run along the lip of the chassis, or are suspended well above the tube sockets (either way works) & so that the plate wires can run flat to the chasis floor, grid wires should be kept short and "jump" over hum inducing wires like plates & heaters. Your heater wires should be WELL away from the speaker jack.

2x100ohm virtual CT - stick a few solder tags under the PT bolt at top right. Run your 100ohms straight to ground here, along with any PT centre taps and the 2 left most filter cap grounds. Keep the preamp filter cap grounded to the input jack.

I don't like the power cord AC wires runing straight accross the PT like that, close to all the secondaries, I usually run them wide around the PT.

6V6 pin 8 connection to the eyelet board - there is a bare wire hanging out of the eyelet? Why? If this grounds out it will kill your tube.

Wires to 12AX7 pin 2 & 7 - you can shorten these greatly, pull them out from behind the board, run the wire from pin 2 straight up to the junctionof the 68K resistors under the jacks, arcing out towards the tube socket. Run the wire from vol pot centre tab direct to 12AX7 pin 7 in a straight line.

[MWJB]

Oh...and you have left off the 25/25 cap that is parallel with the 1500 at the RH side of the board, just about every 5F1 had one of these...some folks might prefer it off, maybe if you are a harp player, or have a guitar with a huge output.

[Lightning13]

Cool, more ideas to try. Right now I'm not even worried about hum. I'm trying to get the input jacks active and sending signal some sort of guitar sound through the speaker. The wiring looks butchered and strung all over the place since I'm doing a lot of trial and error. I'll redo it all and use those suggestions after I get it barkin'.

Do I need to have the input jacks isolated?

Should the voltages at the tube socket lugs be checked with the amp plugged in or not? If not, should I leave the caps charged?

Yep, those power and heater wires are poorly run. They'll be cleaned up soon.

I did try another 6v6 straight out of my Marshall haze with no improvement.

If we take noise out of the equation for now is there anything other than whats been mentioned that I can check just to get some output going? Keep in mind that I did get a loud squeal out of the speaker which seems to indicate that part of the circuit is ok.

Time to some more testing.

[MWJB]

You need to measure voltages with the tubes installed & the power on, measure 6V6 pins 3, 5 & 8 dc volts to ground, highest voltage setting on the meter. Measure 12AX7 pins 1, 6, 3, 8...dc volts to ground again. Measure the 12AX7 voltages at the eyelets on the board that connect to the pins mentioned, saves you accidentally shorting the socket.

Start measuring at the 6V6 first, listen for pops at 6V6 pin 3, 12AX7 pins 6 & 1 as you probe...as you get nearer the front of the amp the pops get louder, if there is no "pop" at 12AX7 pin 1 or 6, then you have inadvertantly grounded or disconnected something.

You said in your first post that the amp hummed loudly...be worried about it, it's not normal...even if hum is negligible, the way you have your wires routed could prevent the amp from functioning properly.

No Fender built champ has the jacks isolated.

[Bruce / Mission Amps]

And... I don't see it in your photos or in response to MWJBs question about it ... but is there a green/yellow wire coming out of the PT (that should be grounded) or are you using a pair 100 ohm balancing resistors across your filament string?

[MWJB]

There are 2x100ohms coming off the pilot lamp.

[Lightning13]

MWJB I just had a bit of fun testing pin 3 on the 6V6. Multimeter black was clipped to ground and set on high voltage DC. I gently touched the pin and got a pretty loud pop out of the speaker and a 1 inch flame off the pin. Multimeter is still alive and no fuses were blown.

My amateur hypothesis is that it's a bad bad grounding issue.

Bruce, there are only four wires coming from the transformer red/blue and black/yellow.

For safety's sake I'm going to pull the board back out, redo the chassis and clean it up. I'll be back.

[MWJB]

Why pull the board out? The board itself looks OK, it's the wires running to the tube sockets that look dodgy & the heaters...& the grounding...Slow down, think methodically, solve one issue at a time...if you keep tearing EVERYTHING out you are not going to make any progress.

Sounds like you might have shorted pin 3 to pin 2...the tube will die in a short while.

What voltages do you have?

You can tell if the 6V6 isn't grounded properly, stick an ohmmeter from pin 8 to ground, what does it read?

[Jag]

Bruce was asking about the PT and it sounds like your answer referred to the OT.

[Lightning13]

The board is the only thing I'm pretty sure about and I plan on leaving it alone, but the grounding wire runs under the board and that could probably be improved.

Also new to Multimeters - 6V6 Pin 8 to ground: .440 K

[Bruce / Mission Amps]

There are 2x100ohms coming off the pilot lamp.

Ah, I see them now... another odd way to do it but that should be fine too.

6V6 socket:
440K on lug 8... that's wrong, it should be 250 to 270 ohms.... but you might be using a blown up multimeter now.
Go to the other side of the 6V6 cathode biasing resistor (250 ohm to 270ohm 5 watts) and see if it is really grounded... sounds like it might not be if your DMM does not have a blown fuse or is not toasted. If it is grounded... make sure there is a good connection from lug 8 to the cathode biasing resistor... also, make sure you have around 220K ohms to ground at lug 5.

[Mandopicker]

The solder joint at the first plate load resistor (100k) looks like it needs to be re-heated too. Not saying it is the cause, but it could be better.

[MWJB]

440ohms seems within tolerance, you should only be reading the resistance of the 470ohm cathode resistor with this test.

[MWJB]

"440K on lug 8... that's wrong, it should be 250 to 270 ohms" It's a 5F1 (~470ohms)...you're thinking 5E3....easily done, I did the same when describing Lightning13's cathode wiring for V1!;-)