Toroid transformer no ouput

[eurikain]

First check if the primary side is ok. Some transformers have tiny heatfuses in it.
Normally no problem, because you can buy the fuses for small money, but before you can change it, you must disassemle the complete transformer. I don't know if its possible without destroying them.

Hmmmm.. yeah no way to disassemble it.. I just sent an email to rapidonline to see if it's possible to send it back and get a replacement one, just in case it turns out to be faulty after trying all what you guys will recommend :)

[Graeme]

I think you have the transformer wired wrongly. Firstly to make sure no damage has happened, disconnect the secondary side of the transformer at the screw terminals and measure the AC voltage between Red and Black - should be 25V AC, also check between Orange and Yellow - should also be 25V AC. If this is ok then the transformer is working.
Assuming that you are making a 70V DC power supply. Connect the Red lead to one of the AC terminals of the rectifier and the Orange lead to the other AC terminal. Then connect the Black and Yellow together. These should not go anywhere else. In this configuration the secondary windings are now in series.
Apply mains power and measure the DC voltage. You should see 70V - 75V DC with no load. Be careful as the capacitors will take quite a long time to discharge.
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Graeme

[Clive S]

eurikain I think Graeme is correct. But lets start with basics First disconnect the transformer and measure the resistance of the primary (blue and Brown) wires it should be quite low if you don't have a meter just use a battery and lamp to see if you get continuity. If that sis OK do the same for the secondary coils. It probably is OK.

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The next step is to connect the primary (brown and blue) to the 230V supply and then as Graeme states measure the voltage on the two secondary coils if you are getting 25V on each you are good to go.
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Try that and report back.

[eurikain]

Hello guys,

Yes, now I understand what I did wrong. I didn't think that black and yellow were meant to be together and go nowhere else and that only orange and red were meant to be used separately on the rectifier.

I'll go do the checks you asked right now and report back in a few minutes... oh boy I hope I didn't break the transformer... or a new one shall be ordered tonight... ! Learning the hard way.. oh boy x)

[eurikain]

So....

[s]Transformer primary is OK, my ohmmeter shows a low resistance as you said Clive.[/s]

No output on either of the secondary coils. When measuring the resistance it works fine, but no voltage comes out....... :'((((((

What's up doc' ?

[Graeme]

You can also measure the secondary resistance, should be have a low resistance on each and a high resistance between them. Have you checked that you are getting mains voltage to the primary. I would have expected that your input fuse would have blown with your original wiring.

[eurikain]

Ok I'm sorry I made a mistake, the low resistance of the primary side was coming from my body --', so here are the measurements using a ohmmeter set to 1k ohms:

primary: no resistance
secondaries:
black+red = high resistance
orange+yello = high resistance
black+yellow = no resistance
red+orange = no resistance

That fuse you are talking about, is it possible to replace it as mentioned by @uli12us ?

[Graeme]

What do you mean by "no resistance" and "high resistance" ? I would expect to see less than 10 ohms between the Blue and Brown on the primary. I would also expect to see less than 3 ohms between the Red and Black as well as the Yellow and Orange. Can you let us know the actual values you are seeing.