Computer Hope

Hardware => Hardware => Topic started by: hyperhedron on May 13, 2008, 01:23:15 AM

Title: testing a power supply
Post by: hyperhedron on May 13, 2008, 01:23:15 AM
how would one test a power supply, to see if it works? i have no other computers to use it with, by the way.

The problem is that my computer suddenly stopped starting up. i press the power button, lights come on, power goes to all devices, fans start up, but the monitor does not come out of standby. I've checked the monitor, video card, and RAM, and they all seem to work. my dad suggested the power supply as a source of the problem, but i have no way of trying it on another computer. He suggested unplugging the motherboard plug, and testing all of the pins with a multimeter, but i'm not so clear on how to do that. any ideas?
Title: Re: testing a power supply
Post by: Dusty on May 13, 2008, 01:40:46 AM
Let Google be your guide.,..

Click here... (http://www.google.co.nz/search?hl=en&q=testing+atx+power+supply&btnG=Google+Search&meta=)

Take care when dealing with live power supplies.

Good luck.
Title: Re: testing a power supply
Post by: patio on May 13, 2008, 04:13:06 PM
Instead of attempting to test the existing PSU a better method  is to borrow a known good one of the same wattage or greater and swap it into your machine...if it runs properly the test is over and you need a new PSU.
The problem with most testers on the market is they won't do a test at full load which is what you need...unless you buy an expensive one.
Title: Re: testing a power supply
Post by: squall_01 on May 13, 2008, 05:32:29 PM
Theres an easier way to find out what you need is a voltage meter an you take the one positive probe an stick it in the 4 pin connector of the power supply  an the negative probe an stick it in the other pin of the 4 pin connector.  I dont recemond doing this unless you know how to really do it.  Theres also a small device that will see if there is current but I'm not sure what it is have to get back latter.
Title: Re: testing a power supply
Post by: patio on May 13, 2008, 05:35:52 PM
This is not a load test and is testing only one component of the PSU....
Title: Re: testing a power supply
Post by: squall_01 on May 13, 2008, 05:40:34 PM
sorry fogot to mention.  I didnt know that I thought if there was current flowing that it was good.
Title: Re: testing a power supply
Post by: hyperhedron on May 14, 2008, 11:47:54 PM
i dont catually have another psu of any kind of similar wattage, so that's out.

squall: when you say 4 pin conector, do you mean the Molex connectors for CDROMs/ the like?

In terms of small device, a multimeter is all i've got.

one more question: how does one start a power supply without plugging it into the mobo?
Title: Re: testing a power supply
Post by: Dusty on May 15, 2008, 12:00:13 AM
Quote
one more question: how does one start a power supply without plugging it into the mobo?

It's shown in the link I already posted - short pin 14 to any common pin (the cable on pin 14 is usually yellow green, the cable on common pins is usually black). Review the link here (http://www.duxcw.com/faq/ps/ps4.htm)...

Quote from: Homer
usually yellow? its most commonly coloured green.

Homer is of course correct - the DC on cable color is green.  Thank you for correcting my error Homer...


Good luck again..

Title: Re: testing a power supply
Post by: homer on May 15, 2008, 12:18:45 AM
one more question: how does one start a power supply without plugging it into the mobo?

by taking a paper clip, or something similiar, and shorting out the green wire to any black wire on the main 20 (or 24) pin mobo connector. dont worry about getting shocked by touching the bare metal on the paper clip when shorting the terminals, there isnt enough voltage there to pierce the skin.
Title: Re: testing a power supply
Post by: homer on May 15, 2008, 12:22:59 AM
Quote
the cable on pin 14 is usually yellow

usually yellow? its most commonly coloured green.
Title: Re: testing a power supply
Post by: squall_01 on May 15, 2008, 03:21:33 AM
I think so but I just call it the four pin connector, I don't recommend a paper clip, Rubber will neutralize the current.  The thing is you have to test it with out it being plugged in to anything.  Then I would set it up to the PC an start it an see how low the levels drop.
Title: Re: testing a power supply
Post by: homer on May 15, 2008, 10:18:59 AM
Quote
I don't recommend a paper clip, Rubber will neutralize the current.

what are you talking about?
Title: Re: testing a power supply
Post by: hyperhedron on May 16, 2008, 12:15:08 AM
Quote
I don't recommend a paper clip, Rubber will neutralize the current.

what are you talking about?
he's talking about a paperclip covered with plastic, i assume

The thing is you have to test it with out it being plugged in to anything.  Then I would set it up to the PC an start it an see how low the levels drop.

when you say without being plugged into anything, do you mean without a mains connection? I know that it is probably a silly question, seeing that you can't test it without power running to it but i'd rather be sure.
Title: Re: testing a power supply
Post by: squall_01 on May 16, 2008, 02:47:41 AM
No rubber so that there isnt a chance of being shoot acrossed the room.  Know I mean into the board at all.  You need something to give the power power but thats all.
Title: Re: testing a power supply
Post by: homer on May 16, 2008, 03:04:43 AM
squall, i highly recommend you become further educated in electronics before making statements that are totally incorrect. you will not get harmed by touching 12 volts with your bare hands.
Title: Re: testing a power supply
Post by: squall_01 on May 16, 2008, 03:19:47 AM
I now that but an incorrection could or even worse  :o
Title: Re: testing a power supply
Post by: homer on May 16, 2008, 03:29:30 AM
there is still not enough voltage to do any serious damage to a person in the event of a short. even if you shorted the wrong wires, there might be a spark, but you will not get shocked.