5F1 First Start Up - Not a good start :)

[gkotlin]

Just built my first 5F1 amp and now I get to learn troubleshooting.  (My 2nd amp build ever, first was 5F6A worked from the first power up, beginners luck).  I was consulting the instructions on the Mojotone site, I bought the transformers from their site. 

Their first time startup instructions show to power the amp up and check the AC voltage on the PT secondaries.  I’m getting 3.3V on the heater wires. 

A couple things I’d like some input on are:
I took the PT red/yellow wire and the green/yellow wires to chassis ground at the PT.  This seemed correct looking at the diagrams as the secondaries seem to have taps that go to ground. 
It wasn’t until I was pretty deep into wiring up sockets, that I noticed I should have swapped the 6V6 and 5Y3 socket positions in the chassis.   As such, I took my heater wires from the PT to the tube socket, then to the lamp and then over the 12AX7.  I didn’t think this would matter as they all seem to be in parallel I believe.

Also upon first power up attached to a speaker with tubes in, I still get 3.3V on the heater wires (no surprise) and I’ve got a squeal that appears after power is on for a couple of seconds.

Any guidance on troubleshooting and initial power up is appreciated.

Had to run the grand kids to basket ball practice, before I could really dig into troubleshooting (posting court side now).   

[sluckey]

If you are measuring filament voltage with one meter lead connected to chassis then 3.3v is correct. If you want to see 6.3v you will have to put one meter probe on a filament lead and the other meter probe on the other filament lead. IOW, measure voltage across the entire filament winding rather than just half the filament winding.

[gkotlin]

Thanks Sluckey.  In hindsight it makes sense that I’d only see half the voltage since the transformer winding has a center tap to ground.  I’ll double check that and keep looking for any mistakes in the wiring.

[gkotlin]

I've gotten rid of the squeal by swapping the wires on the output transformer.  Now I can hear a little guitar when i turn the volume up all the way on the guitar and the amp. 

One thing I did realize is that I've got a Blackface Champ output transformer from Mojotone which on its site shows it is 7k.  The Tweed Champ output transformer specs on their site show 5k.

Could this be part of the problem?

[sluckey]

Could this be part of the problem?

Not likely