Hello all,

Firstly, I must say it's been a while, but I'm back. For those that's still around since 2009, my Fender Harvard 5F10 build and my Fender Deluxe 5E3 builds both are done and sound really good. Thank you to all that are still around to answer my questions...

I'm making a Fender Champ (5F1 circuit) from a recycled chassis/transformer. The transformers specs seem to fit the specs for the project, however I've come across a slight problem - the wires aren't exactly color coded like today's are.

Coming out of the one hole, I have two black wires, a green wire, two red wires and a red/yellow wire.
On the secondary side, I have two orange wires, two brown wires, and two yellow wires.

Based from my prior builds, I knew the two black wires hook up to the fuse holder and the switch (I added a switch in by itself as compared to it being integrated in the volume pot), which that ended up being ok. I also have the power cord wired up already as well. My trouble is distinguishing the 5V and 6.3V wires on this transformer. I'm including a picture of the chassis, a hand-drawn-and-slightly detailed picture of the wiring, and a paper with resistance and voltage readings to start.

Please, any help is greatly appreciated...
amp chassis.jpg
These are speculation and could be wrong, but I am reasonably confident they are right. I have no idea what your voltage reference was (where the common lead of the meter was) so your voltages may not be right. By the way, did you remember to short the leads of your digital ohm meter and note the resistance so you could subtract it from the measurement?

--The black wires should be the mains input.
--The red and red/yellow wires should be the high voltage with the red/yellow wire being the center tap.
--The orange, brown, and yellow wires should be seperate, lower voltages used for the tube heaters. The yellow should be 5v and the brown could be 2.5v. Normally the 6.3v coil has green wires, but these may be the orange on your unit.
--The green wire may be connected to the case and/or the transformer core. Have you measured it?

The heater voltages will all be somewhat higher when you are measuring with no load connected.

Hope this helps.

This may be helpful, too.

By the way, your wiring for the primary side is not up to modern standards. You want the black wire from the line cord going to the fuse, then the fuse to the switch, and the switch to the black wire on the PT. The white wire from the line cord goes directly to the other black wire of the PT.
Last edited by Invader Jim at Nov 17, 2013,