Test a power supply?

[JohnE.]

I've got 2 older ATX power supplies that I'm trying to determine whether they work or not. How can I test an ATX power supply without it being connected to a mobo and without a volt meter? Isn't the fan supposed to come on regardless or does it need a signal from the front panel power switch/header of the mobo?

Also, one of the PS keeps blowing a fuse everytime I plug it in and apply power... any ideas?

JohnE.

[Reknup]

On the PS that blows fuse... Check the Voltage Meter on the back of the PS.... Try both settings... If it keeps blowing fuse... Chuck it!

Some PS's will only turn on if they are connected to a Mainboard... They have a detection system of some sort...

[Ruler2112]

There was a post not too long ago that shows the pin-outs on the ATX power connector. You have to run a wire from one pin to another to get the PS to turn on. This kinda fakes the PS out, making it think it's hooked up to a MB. Sorry I don't have a link for ya.

[Telexen]

No ATX will power unless connected to a motherboard...AT PSUs will though

[goldenbuddha]

That is incorrect Telexen. You can power on ATX PSUs without connecting to a motherboard. As shown here


Edit: I saw this nifty testing hardware for PSUs on Frozencpu.com Check it out!

[Telexen]

Okay...you can't do it without a motherboard or making it THINK there's a motherboard and case power switch there

[JohnE.]

Thanks for the replies. I was pretty sure an ATX would have to be connected to a mobo but never had a definitive affirmation. I got one of the PSU's to power up after connecting it to a mobo and it posted fine so is working a-ok. I had that one in the closet for over a year and never knew if it worked or not, heh. The other one is going in the trash.

JohnE.

[JohnE.]

Got a couple more related questions now that I've got a known good PSU... I'm trying to put together a system from old parts.

I originally tested the "good" PSU on a friends mobo which he had over here for me to set up for him. So far, so good but when I hooked it up to an old Slot1 board (PCChips M710, yuck) that I'm not sure works and that I've had collecting dust in the closet, nothing. No PSU fan, no CPU fan. As far as I can tell I've got the front panel connectors on correctly (the manual only has tables; no diagrams, so is a little hard to decypher) but still no go.

So my question is will an ATX PSU power up (and the fan come on) when connected to a mobo even if the mobo is dead, assuming the front panel connectors are correct?

Also, something I've wondered about before - I noticed the mobo screws (all but one) have those red (cardboard?) washers/insulators on them. Do those have to be on there to prevent a ground loop or could they all come off without causing a problem? I'm assuming only one screw has to contact the board/case to provide grounding but I could be mistaken.

JohnE.

[JohnE.]

^^Bump^^

[JohnE.]

^^Bump again^^