marshall 50/50 output trany wiring?

[ktolon]

Hi, I was hoping someone could help with wiring info. I have a mercury output transformer i would like to install in one side of my Marshall el34 50/50 Monoblock power amp. My question is, what wire is on the stock trany. is CT? On the primary side i have three wires , one black wire that goes to a tube base ( vb4 per schem.), a red wire that goes to the other tube base ( vb3), and a white that goes off to the caps board. On the Merc. trany. I have the numbers 1,8, and 2 CT. Thanks in advance for any help you can offer, Keith

[defaced]

The wire that goes off to the power board is the CT for the OT primary.

I'm not familiar with this amp, but if it has a NFB (presence control), and if you get some funky oscillation when you swap the tranny, swap the wires that go to the power tube board.

[kor]

According to what you wrote in your post, The white wire is CT (center tap).
The black wire is pin#3 (plate) of one EL34/6CA7, and the red wire is pin#3 (plate) to the other EL34/6CA7.