Wiring power transformer

[James_rc]

First off, apologies for another newb question. My Mojotone transformers came today; I'd like to make sure I'm reading the wiring diagram for the power transformer correctly. Can you let me know if the following is correct?

High Voltage
- 355v high voltage red wires to HT1 and HT2
- 50v blue/red to PT bias tap
- 0v red/yellow to ground

6.3 Volts
- 6.3v green wires go to the pilot light and heater terminal strip
- Green/yellow to ground

Faraday Shield
Orange to ground

120 Volt (United States)
- 120v white to power switch
- 0v black to power switch neutral? (Most unsure about this)

[sergio]

Correct!, but what do you mean by POWER SWITCH GROUND?

S.

[Stephen1966]

6.3 Volts
...
- Green/yellow to ground

You might tape this wire off and use an artificial centre tap instead.

120 Volt (United States)
...
- 0v black to power switch ground? (Most unsure about this)

0V black - goes to the Neutral side of your AC wall supply. You don't want to connect this to your ground line!

With no schematic or layout here I can only guess your topology but if you use an IEC connector for the wall supply, from the Hot pin, the lead should go to a fuse and then through the power switch to the 120V white line. If there's a surge, the fuse will blow first, protect the switch further down the line and the transformer.

Check this out: http://www.valvewizard.co.uk/standby.html

[James_rc]

Thank you, both!

[James_rc]

Correct!, but what do you mean by POWER SWITCH GROUND?

S.

I used the wrong terminology. Should’ve written neutral.

[James_rc]

With no schematic or layout here I can only guess your topology but if you use an IEC connector for the wall supply, from the Hot pin, the lead should go to a fuse and then through the power switch to the 120V white line. If there's a surge, the fuse will blow first, protect the switch further down the line and the transformer.

Check this out: http://www.valvewizard.co.uk/standby.html

Thanks so much for this! Working from the IEC switch to the PT (rather than the PT to IEC) really helped make sense of things. I really spent time tracing what I was seeing on some layouts and made a bunch of notes in a word doc.

I'm making Ryan's Fairfield County. One of the Fairfield layouts has a white and black line coming out of the PT, and I think I'm realizing the white there is neutral, and black is the live.

[timrobertson100]

Sounds like you’ve got this, although note your power is not going to “0v” on the PT - it’s just connecting to both ends of the primary winding, into which AC is fed.

In Europe I gather it’s necessary to switch both live (after the fuse) and neutral in our power switches. That may explain some variation as you look at examples.

It’s good you ask these kind of questions by the way. Before you wire stuff up, I recommend reading some approaches to first power up - some continuity tests you do before wiring in the transformer secondaries.

[Stephen1966]

I think I'm realizing the white there is neutral, and black is the live.

Yes, it's the other way round for you with your Mojotone PT - your white is live (or hot) and your black is neutral. The layout (from L to R) shows white neutral, green earth, black live. The live wire goes first to the fuse, then to the switch, then to the transformer. This is the way it should be regardless of whether you then run the neutral to the second pole of a double pole switch or directly to the transformer. If you label the layout with your transfomer's colour codes and follow the path in the layout, you will be fine. The layout is okay here...

From Google:

US AC power circuit wiring color codes
The protective ground is green or green with yellow stripe. The neutral is white, the hot (live or active) single phase wires are black , and red in the case of a second active.

From Mouser:

https://cz.mouser.com/ProductDetail/Sch ... DdeA%3D%3D

[James_rc]

Thanks so much, guys! Seriously.

[martin manning]

I think I'm realizing the white there is neutral, and black is the live.

Yes, it's the other way round for you with your Mojotone PT - your white is live (or hot) and your black is neutral.

Reprising what Tim said above, in this case the primary coil is continuous, so it doesn't matter which lead goes to where, they are just the two ends of the 120V section of the coil. The colors are arbitrary. That said, it's nice to keep the black with the black (hot lead) from the power cable, and the white with the white of the neutral lead.