power supply question

I just plugged in a NEW out of the box power supply to see it work before I install it in my PC, I made sure it was set at 115v, I flipped the switch and nothing. Is there a circuit that needs to be completed in order for the power supply to work or should the fan and light work sitting on my desk? thanks

i would have thought that it would work even without being plugged in.

in my opionion something is wrong.

As far as I know, there isn't anyway to plug just the PSU into the wall without actually placing it in a case first. Just plugging it into to wall won't do anything. It has to actually be plugged into a motherboard first and then the power button on the case needs to be pressed before the power supply will actually work.

But chances are, if it's brand new as you say, that it will most likely work. Besides, there isn't any harm in placing it into your system so just replace it.

why couldnt you just plug it straight into the wall?

Well, think about it. Normally, when you plug your computer into the wall without pressing the power switch in the front, nothing happens.

Seriously, try it. Shut down your computer, unplug the power cord, and then plug it back in. Does anything happen? No, nothing happens. It doesn't do anything until you physically press the power button on your case and allows the circuit to complete and your system to power up.

It would be the same even just sitting out of the case. It's virtually the same thing. If you plug JUST a PSU into an outlet without any button to allow the circuit to begin or complete nothing will happen. I suppose if there is some sort of indicator light or something on the PSU then that will turn on, but the fan shouldn't start turning or anything like that. As far as I know...

Just plugging it into the wall won't start it. If you want to test it without a PC, you will need to short the green wire on the 24 pin ATX Main connector with any black wire (while the PSU is plugged in).



Basically that simulates pressing the power button on the case when everything is plugged in