Schumacher Fender Twin Transformer Wiring Question

[pdrie]

I'm a long time lurker (Primarily because I don't know the answers to most of the questions asked here) who needs some help with a seemingly simple question. I'm starting to build an amp using a vintage Fender Twin 22756 power transformer, manufactured by Schumacher. The transformer has seven wires on the secondary. Based on the wiring digrams and schematics that I have seen, I expected six wires on the secondary.

I checked the transformer secondaries and found the pair of green heater wires and the center-tapper HT leads working, as expected. The bias tap has me a little confused. This in addition to the two leads for the heaters and the three for the HT supply, there are two additional wires on the secondary, one orangish or light brown, and one red. The voltage between each and the center tap is about 63 VAC with the primary at 118 to 120 VAC, the voltage acreoss these two leads is about 42 VAC. Any idea what these two leads are and which I should use for the bias tap?

Thanks in advance for your time.

Paul

[M Fowler]

340-0-340 secondary 3 wires if center tap
40v bias 2 wires
6.3 filament 2 wires

That should be 7 wires total

I don't have the wire colors but on the 40v tap has one wire to ground and the other goes to a 470R and In4007 diode in series to bias pot.

Mark

[stubbyfex]

Hello!
The 022756 was used in a the CBS twin, and Dual Showman. The red leads are high voltage, with the red/yellow being the center tap. The Bias wire is red/blue. The green ones are filaments. The orange wire is a shield wire that is internally connected to the frame. Here is a schematic of the dual showman showing the hook-ups.

[pdrie]

Thanks for the replies. The orange shield wire was the one that was confusing me (not a difficult thing to do, of course). The AB763 schem that I have wasn't as clear and didn't show the shield ground.

Thanks again.

Paul