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Testing a PSU

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April 19, 2010 5:42:37 AM

Long story short I was working on my computer and messing with cables near a hard drive and something sparked and burned on it. The computer shut down. I unplugged that drive but then the system struggled to turn on and shut down after a second. I unplugged all of my drives and then it started up but something on the board blew and was on fire. I know something burned on the drive and there were two spots on the board that blew (optical output and something else).

I have had zero issues wuith the PSU. It is a 3 year old Corsair 750 Watt True Power. I hadn't been having any issues with the computer and I think I merely bumped something near the harddrive/video card.

Anyways, can I just test the PSU by checking it with a voltmeter? Or would that alone not tell me if it is "safe" to use or not. It doesn't smell burnt or anything but I'm wondering if something was wrong with it's shutdown safety features and such. Any ideas?

More about : testing psu

a b ) Power supply
April 19, 2010 6:13:57 AM

i would just plug another PSU into your system, or try your PSU in a friends system to see if it still works.

Most PSU's these days do have short circuit protection though. I mean, I have a cooler master which ive short circuited a few times while modding fans, and it just shuts off the system. after I fix the short i can just turn it back on again.

same story with a 6 year old antec power supply I have.

good luck though, and if it is broken, see if it is still within warranty.
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April 19, 2010 1:37:31 PM

If you like you friends i wouldn't try your Dieing/dead PSU in there system lol.Sparks, fire, usually means the PSU is seriously screwed, if you are set on testing it, find an old system, something you wont care about frying and see if it boots.From what i read your HD is gonzo's and if there's sparks and fire on your mobo theres a good chance thats gone aswell.
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a c 144 ) Power supply
April 19, 2010 2:39:51 PM

Get (or borrow) a digital multimeter and check the PSU.

Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.

http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is bad. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

Corsair is one of the few brands that has overvolt, undervolt, and overcurrent protection in their PSU's.

Hoser is right. I'm willing to take a PSU from one of my systems to use to test his system, but I would never allow a friend to test a questionable PSU in one of my systems.
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a b ) Power supply
April 19, 2010 2:46:56 PM

that was indeed a bit dumb of me to suggest putting the PSU in a friends computer.

My apologies
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April 19, 2010 10:56:21 PM

Thanks for the info. Sorry if it is a dumb question, but when you say:

"Then repeat the checks with the PSU plugged into the computer to put a load on the PSU."

How to I go about that since that plug would be in the board? Or do you simply mean put everything together and see if I have booting/shutdown issues?
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April 19, 2010 11:16:29 PM

I did something like this on an old system I had. My PSU fried along with my mobo but my mobo never caught on fire so I'm gonna guess that your board and PSU are definitely gone
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a b ) Power supply
April 20, 2010 3:28:51 AM

simply for marketing, theres nothign special about them!
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April 23, 2010 1:44:53 AM

Well, the PSU seems alright. I have my new system up and running.Thanks for the tip!
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a c 144 ) Power supply
April 23, 2010 3:55:36 PM

littlefire said:
Thanks for the info. Sorry if it is a dumb question, but when you say:

"Then repeat the checks with the PSU plugged into the computer to put a load on the PSU."

How to I go about that since that plug would be in the board? Or do you simply mean put everything together and see if I have booting/shutdown issues?

Glad you are up and running now.

It's a little late to help you, but you can carefully probe the back of the main connector to check the voltages.
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April 24, 2010 1:25:59 AM

Well, I had ordered a new 750 Watt PSU (my old one was actually only 620, NOT 750 as stated in my original post). However, the computer will not boot with the brand new psu!

The gray wire on my old psu is exactly 5.00 but on the new one it is only 4.62. That is likely the issue, right?

Details here:

http://www.tomshardware.com/forum/280703-28-upgraded-co...
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