Wiring in output transformer in jtm45

[timmyjoe]

Wiring in an output transformer to a Marshall jtm45 clone. The primary side is what I’m unsure of. Mercury magnetically lists the wires in the following order black, brown, red. Highest resistance is between black and red. My assumption is that brown would go to the capacitor and black and red go to the tubes.

[sluckey]

Sounds logical.

[passaloutre]

Assuming this is the right transformer, it would appear you are correct:
https://www.mercurymagnetics.com/wp-content/uploads/shop/specsheets/O45JT-16.pdf

[timmyjoe]

As always, thanks!
Yes that is the transformer.

[timmyjoe]

Got it playing tonight, but blew the fuse that is closest to the power in. It might have been me turning it off and then on and off and on too fast? I don’t have a standby switch on it.

Or maybe it is a real problem? Any advice on what to do next? Thinking of taking out the tubes and doing a full restart procedure to be sure things r ok.

Voltage on the DC was a little low on the side of the board closest to guitar jacks. Amp had more gain than I was expecting. I’ll get a fuse tomorrow.

[pdf64]

  … blew the fuse that is closest to the power in…

For that to be meaningful, we need to know the layout of your amp.

As you’ve not mentioned one, I guess you’ve not built yourself a lightbulb limiter yet?
For new builds, repairs, or just checking unknown valves aren’t shorting, I think they’re an essential item for a tech’s bench