Power transformer

[salvady68]

Oppsss I haven’t seen other replies.... In my case, on chassis is writed 50/60 Hz, so I think will be ok

[Roe]

The key word is "sometimes." If your Epiphone amp's PT doesn't run hot (too hot to touch for more than a few seconds, or it's dripping melted varnish) then there is no problem. A 50 Hz mains frequency requires a little larger core to deliver the same power, but there is probably enough margin to cover it.

exactly - thanks

[andresound]

Applogies for derailing the thread. But thanks

[salvady68]

Hi to all! finally it's arrived,now I have to rewire for 230V, were I can find the specs with the colors relates to the primary tensions? In your opinion wich trasformers brand two rock use in their amplificators? How I can attach pics?

[martin manning]

There should be a six or seven digit number on the transformer somewhere that indicates the manufacturer and date. Can you see something like that? It might be difficult to get a diagram, with TR being so secretive and all. Post some good pictures of the power section that show which leads are connected and which are not. Do you have a DVM to measure voltages? Do you have access to any other test gear or a Variac?

[pompeiisneaks]

Hi to all! finally it's arrived,now I have to rewire for 230V, were I can find the specs with the colors relates to the primary tensions? In your opinion wich trasformers brand two rock use in their amplificators? How I can attach pics?

To attach pics, you just use the 'attachments' tab below the edit window when you're posting. Its behind the 'options' tab that defaults to the front. Add one or more picture attachments, and then if you want them 'inline' with your text, you can choose where you want them and click the 'place inline' link. If not all attachments just get put at the end of the post as links.

~Phil

[salvady68]

Now I’m not at home but I toke any pic, unfortunately I can’t load pics. On the transformer bell, under a blue tape, there are this digits: 40-17291 and 166-1027 made in usa.
The transformer has 5 primary windings and two are linked togheter, I don’t know how.
Tomorrow A friend gives to me a step down transformer so I can take some voltages...
Thanks for the replies, now I try to attach the pics!

[martin manning]

...

[martin manning]

The PT was made by Magnetic Components, but it is not a standard part. I see some taped-off leads (possibly 5VAC from the yellow color); will have to study it a bit. Can you trace out the whole power transformer primary circuit, from the IEC power inlet through the fuse and main power switch to the transformer? Include the wire colors too. Below is a Fender diagram, and it has a double-pole main power switch, but this is the part you need to understand. There could be more than two wires going into the transformer, in fact that is what you are hoping for, typical of a 120/240 dual primary.

[salvady68]

The PT is pretty similar to this http://www.classictone.net/40-18042.pdf but mine has also a 100V winding and the colors of the wires doesen't corrispond.

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The primary circuit is not like the fender one, the power switch and the fuse are in serial to the IEC power inlet and the primary as you can see in the picture
So for the 120V now are conected the white/white brown and the black/black white. The black is on the opposite side from the others, like the gray and the brown that are not connected on a terminals
Now I try to contact the guys at magnetic components for asking support

[martin manning]

Ok, if you can get MC to help you with a diagram for that transformer that would be great. Otherwise, there are techniques that can be used for mapping out the connections. In principle, all you will be doing is changing the wiring from that shown in the first diagram on the second page of the data sheet you linked above to the third diagram.

[salvady68]

Ok, if you can get MC to help you with a diagram for that transformer that would be great

I hope...but I don't think they replies me

Otherwise, there are techniques that can be used for mapping out the connections.

Maybe measuring impedance? I would like to learn those techniques

I have tested the amp with a step down transformer, suonds awesome! I have measured 420V on cathodes, do you think is correct voltage?

[martin manning]

420V is not correct for cathodes; anodes maybe, unless you are measuring 0.042V. I'll post a diagram later on the primary in case you get no help from MC.

[salvady68]

sorry!!! anodes

[salvady68]

Dear Martin, I was looking at the diagram and thinking about your words...and then I realized how stupid I am Maybe it is sufficient to connect the two windings in series instead of in parallel. I also have to replace the fuse with a half-current rating, right?