I recently purchased a case with a 500W power source. I wanted to test the power source so I hooked up a 180mm fan to it with a molex connector. When I flipped the switch on the power source nothing happened. The PS WAS plugged into AC power. Can a power source be tested this way with practically nothing hooked up to it? I remember a couple years back a friend of mine just took a power cable, hooked it up to the PS and flipped the switch; it ran. Does it sound like I have a dead power source?

To answer your question, you don't have a dead power source.

Power supplies need a signal from the motherboard to power up. This signal can be simulated by jumpering a couple of pins on the connector. I would rather not supply you with that information if you aren't used to dealing with hardware.

"I recently purchased a case with a 500W power source"

Then why would you need to test?
Ebay has tester:)
http://search.ebay.com/psu-tester_W...

Or Plug the psu power connecter to Motherboard with fan the board will then get power that will start the fan(s)

Off topic subject: this reminds me of the time my lawn mower wouldn't start. i thought perhaps the spark plug. checked it, it looked good.....so maybe the spark wasn't getting through. so i plugged the the lead into the spark plug and just let it and the spark plug hang down above the ground. then i pulled the starter cord, watching for a spark on the plug as i did. yep, there's a spark, fine ! Plugged it back in, fired up but the mower still wouldn't start. took it for repairs and the mechanic said i was a fool for doing what i did......i could have caused an "ARC" and blown myself to bits. he said don't mess with things you don't know LOL

http://www.youtube.com/watch?v=mQuJnnQuPWM&mode=user&search=

Rob, Central Coast
NSW Australia

Folks,
Thanks for your response. I actually built a computer before. The first time I did, I didn't check the power supply and I bought it separately! I just wanted to check and be sure before the return time on the case runs out. But at least I learned something; power supplies depend on signal from motherboard to start up! Actually, I don't even have the motherboard yet! I'm only a week or so into this project. Thanks to all for responding!

If you jumper a wire on the main ATX plug from the green to any black, then plug in the power cord & hit the switch on the PSU, the fan will spin up. But all that really tells you is that the PSU can power up a fan...lol

When your friend fired up a PSU with no motherboard attached it was probably an AT power supply. Most would power up with no load attached.

Rob, testing to see if a plug is getting the spark by having it touch the motor ground and then cranking is the most common method practiced by backyard mechanics. It's unlikely you would have blown anything up. You'd have to be in a closed room that was full of flammable gas (or maybe an unventilated grain silo) before you'd need to worry about that.

DAVEINCAPS
its too bad you can't test a PSU by connecting the 20pin ATXPWR plug into the spark plug port on the mower, pull the ripcord and see if the mower fires up LOL.

http://www.youtube.com/watch?v=mQuJnnQuPWM&mode=user&search=

Rob, Central Coast
NSW Australia

Yeah, I think testing them like that would show all the PSUs as bad. Too bad it's always so hard getting the mowers started. It'd be a lot easier to get my son to cut the lawn if it was easier to start the thing.