PC SMPS component ID?
 

You know the bog standard PC SMPS, often in a grey case with a kettle lead?
Usually something like 13A @12V and 5V supplies?

I notice there is a component beneath the kettle lead in connector. It says 230v on the outside but is not a voltage setting. I think it is a thermal overload of some kind. It reads O/C on a multimeter. Hence I wonder if it is a binary device that switches on above a certain temperature, enabling a shut-down circuit to be activated?

I am just using an old case for another project and am deciding whether to keep this component, alongside the useful RFI measures on board.

Re: PC SMPS component ID?
 

I think you'll need to give us a picture. Lots of components could say '230V' on the outside. The most obvious would be the mains voltage selector switch, but few PC power supplies have one of those these days.

Chris

Re: PC SMPS component ID?
 

It’s usually a red slide switch of some description. Might be fixed in some of the cheaper ones. Usually switches the inlet diode/capacitor arrangement.

Re: PC SMPS component ID?
 

Ah, that sounds possible. Thank you.

Re: PC SMPS component ID?
 

I wanted to, but frustratingly I can't upload photos from my iPhone to gmail at the moment, and that's the only way I can post them on the site...

Re: PC SMPS component ID?
 

Yes, as MrBungle says, if it's a red slide switch, it's the voltage selector. It's wired so that it changes the input arrangement from a bridge rectifier with both reservoir capacitors in series on 230V, to a voltage doubler on 115V. That way the half-bridge primary side of the power supply always has a 300V-ish supply with a centre tap (for high frequency switching purposes) at the junction of the two reservoir capacitors. I've always thought it quite a neat arrangement. I'm assuming that it's been made obsolete by the advent of power-factor-correcting input stages which don't work that way.

Chris

Re: PC SMPS component ID?
 

Very neat idea indeed! Thanks for de-mystifying.

Re: PC SMPS component ID?
 

This I'm guessing

Re: PC SMPS component ID?
 

Truth is, pretty much all of the PC-type SMPS I've seen for the last decade have dealt with the issue of 110/220V switching by themselves and not had a separate user-accessible switch for this.

Re: PC SMPS component ID?
 

An ATX PSU from a Dr. Dre Beatbox on which I'm working (see seperate thread for details) has two points on it's PCB marked 110 & 230v and designed as described by Chris Jones in post #6, but no switch is, or ever has been, fitted to it.

Re: PC SMPS component ID?
 

Most of them will work from about 90 to 265v. They also work fine on DC; I’ve brought a smaller switcher up on three bench supplies in series. Amazingly robust little things.