Bridge rectifier go poof

[blfinche]

What did I do wrong? I hooked the ac input to the 2 posts not marked with the positive and negative. As soon as I applied power I got the magic smoke.

I'm using a 28v toroidal transformer and a 35amp 1000v bridge rectifier. I measure the voltage from the transformer and it was 29 volts.

Thanks,
Bobby

[Al_The_Man]

You sure they were on opposite corners, not adjacent posts?
Is the bridge shorted now? was just a capacitor hooked up to the DC side or?
Al.

[HayTay]

Originally Posted by blfinche What did I do wrong? I hooked the ac input to the 2 posts not marked with the positive and negative. As soon as I applied power I got the magic smoke. I'm using a 28v toroidal transformer and a 35amp 1000v bridge rectifier. I measure the voltage from the transformer and it was 29 volts. Thanks, Bobby

Bobby,

Those markings are not Positive (+) and Negative (-), they are Positive (+) and AC (~). If I remember correctly, the matched connectors are oriented diagonally. See Wikipedia's explanation of the Diode Bridge (with pictures). Note the diagram with the AC Input, DC Output and Load labels in the section devoted to Output Smoothing. Be sure to verify proper connections by tracking down the "Data Sheet" for the bridge rectifier (and other components) you're using. Can't find the right Data Sheet, contact the company you purchased the component(s) from, they should be able to provide it or direct you to the link on the manufacturer's web site.

I see another bridge rectifier in your future. Be careful with bridge rectifiers, a lesser known name for them is "bridge rectal-fryer". Make sure you take precautions so that you don't find out why... the hard way.

[HobbyCNC]

Originally Posted by blfinche What did I do wrong? I hooked the ac input to the 2 posts not marked with the positive and negative. As soon as I applied power I got the magic smoke. I'm using a 28v toroidal transformer and a 35amp 1000v bridge rectifier. I measure the voltage from the transformer and it was 29 volts. Thanks, Bobby

Bobby,
Look closely at the "minus" sign. I'll bet it is a wavy line signalling AC. I've attached a PDF and a JPEG that shows the rectifier "pinouts". It is a sectional cut from the package wiring diagram included in the package.
Hope this helps!

[handlewanker]

Hi blfinche, one of the golden rules before connecting up any electrical 'quiptment is to check the resistance of the connection point.
This means that if the resistance is low then either a dead short exist or you've got the wrong set of contact points.
If you don't test the connection then just putting the plug in will result in a heavy current flow and goodbye anything that is in the line, diodes, transformer or worse a fire in the cables.
I would have thought you would have had a fuse in the output of the bridge rectifier/voltage regulator.
Moral:- Don't go blindly in where.........
Ian.

[blfinche]

I think I have it. I did not connect diagonally. I thought the ~ was a negative sign. So I should connect to the ~ and the corner diagonal to that?

Thanks,
Bobby

[Al_The_Man]

Originally Posted by handlewanker Hi blfinche, one of the golden rules before connecting up any electrical 'quiptment is to check the resistance of the connection point.

The problem with checking a semiconductor on the normal resistance range on a modern meter is that it will not show conduction due to not enough voltage to forward bias the device, so it shows high resistance, you would need to have a meter with a diode check range.


Bobby, the AC connections on a bridge are the ~ signs, and generally are on opposing corners, but adjacent posts cause a short.
Al.

[epineh]

Yup you have it now Bobby, connect the AC to the ~ and the diag opposite corner, the DC goes positive on the + side and the negative is on the diagonally opposite corner.

The way you had it originally meant that there was a dead short across your transformer secondary on one half of the wave, usually the weakest part gives way, in this case sounds like the rectifier, hopefully it didn't damage the transformer, check your voltages once you have it correctly wired, and might not hurt to put a fuse in the circuit.

Good luck.

Russell.