Transformer Data

[oldschooltube]

This is killng me. Does anyone know where to find data on old/obsolete transformers? I have several made by Tresco which bear the markings "pa665" and several made by Reliance Electric with 64969-A printed on them. Alas, I cannot find data on either. Any Ideas?

[fooeywuffle]

Are these sealed, or can you get to the wires that go to terminations? I measure the size of the winding wires for current rating, and if you can figure out what winding is the 120 volt, it is fairly easy to figure out what one is. Figuring out the primary is by resistance determined by the physical size of it. Usually primary is the one wound on bobbin first.

[ChrisA]

Originally Posted by oldschooltube

This is killng me. Does anyone know where to find data on old/obsolete transformers? I have several made by Tresco which bear the markings "pa665" and several made by Reliance Electric with 64969-A printed on them. Alas, I cannot find data on either. Any Ideas?

You have to measure them. It's not hard first us an ohm meter and figure out leads are conects to which windings. Then get low voltage transformer, a 6.3V heater transformers or an AC wall wart power cube. Conect that to which ever to think is the primary, no real harm if you gues wrong. Measure voltage in the other windings. Now you have the turns ration.

To get the VA rating just weight it and compare to others.

Finally test it with a load resistor. Make sure you have a fuse and a din bulb tester.

Takes maybe 15 minutes to figure it all out but you should do the load test a little at a time, add a few miliamps, let it run 15 minutes and check for heat.