Transformer Identification

[hgg]

Hi,

I found a transformer lying around and I was wondering if I can use it for a small power supply.
Can you help me identify if it is a mains 220V transformer?




Red/Black pair resistance is 106.4 Ohm and yellow pair 0.9 Ohm.
Red/Black looks like its the primary side but 106 Ohm seems a bit low for 220V.

What do you think?

Thank you.
George.

[Zero999]

That sounds right to me. What resistances were you expecting to measure?

[hgg]

I don't really know.
I am also measuring 0.9MOhm between the metal casing and the black wire.
Is this normal?

[planet12]

0.9Meg / 900k is very very low between a winding and the metal shroud. If your measurement is correct, the insulation has broken down and the transformer should be thrown away (or rewound, if you're into that kind if thing).

Make sure you've got good contacts between your meter probes and the winding and shroud, with your fingers not touching either (or any other stray paths between the two points), and check it again.

If it checks out (your meter should read it as an open circuit), the next step I'd do would be to connect the primary in series with an incandescent light bulb, then to the mains (careful! Use isolation transformer if you have one, RCD/GFI as an absolute minimum, keeping in mind mistakes = electrocution). The bulb should not come on unless you short the secondary wires together - and you'll also be able to measure the secondary AC voltage while you're at it.

If the bulb lights with the secondary open, either it's not a 220/240V rated transformer, or it has shorted windings somewhere.

[hgg]

0.9Meg / 900k is very very low between a winding and the metal shroud. If your measurement is correct, the insulation has broken down and the transformer should be thrown away

That's what I thought...
The measurement was correct.
I tried to open it to see if I can find the short but I destroyed it...  I damaged some of the windings.
It was packaged like a tank.  Inside all around it had a very crusty yellow compound, (maybe some
kind of glue?).

Probably it was faulty.  I wish I had waited a bit longer so that I could have tried your advise to
check it on the mains.

Anyway, thank you!
Regards,
George.

[miguelvp]

Closest I could get is this:

4-251V-34800

And that is for a betamax vcr rated for 33 watts and multiple outputs, but the poster mentioned 120V input, that doesn't mean it wasn't capable of dual voltage.

http://www.antiqueradios.com/forums/viewtopic.php?f=2&t=220755

Nope, no dual input, picture of schematic is too big to attach.

http://s17.photobucket.com/user/steviefan1/media/sanyoVCR4900powersup_zpsfee695f1.jpg.html

But since it's destroyed it doesn't matter much

[planet12]

The crusty yellow compound would be varnish. Transformers are normally vacuum-impregnated with it both for extra insulation and also to stop vibrations due to magnetic effects (an iron core transformer can have magnetic flux densities in the 1-2 tesla range inside it).

[hgg]

Now its too late...  I destroyed the poor thing.    
Anyway, thanks guys for your suggestions!
George.