How do can I check PS to see if it is working?


Old 04-06-08, 05:58 PM
Thread Starter
Join Date: Jun 2005
Location: USA
Posts: 649
Received 0 Votes on 0 Posts
How do can I check PS to see if it is working?

I have an emachines computer that has died. I suspect that the PS has died. But I also know that emachine computers have a history of taking out the motherboard when the PS goes. I have a spare PS already. They are both ATX PS's. Can I test the power output of them without them being installed into the computer? If so is it correct that I should be reading 12vdc and 5vdc on the connector that has 4 wires. 2 black, 1 red, one blue. At least I think the other is blue. Thanks for help.
Sponsored Links
Old 04-06-08, 11:05 PM
Join Date: Apr 2008
Posts: 6
Received 0 Votes on 0 Posts
You can check all voltage from your PS without being hook up the the machine
The only problem is...

You have several connectors ( to connect HD , Floppy and Cd-drives) that run with 4 pins cable. And the 20 pins connector that goes to the motherboard. You can find a detailed of the voltages for this 20 pins connector on the web.

You will need a digital voltmeter and measure dual power supplies like this one.

More question , please let me know
Old 04-07-08, 03:46 AM
Thread Starter
Join Date: Jun 2005
Location: USA
Posts: 649
Received 0 Votes on 0 Posts
Ok, I have the digital meter. Where can I find the pin out connections schematic on the internet to know what points to test? Thanks for your help.
Old 04-07-08, 10:25 AM
Pendragon's Avatar
Join Date: Jul 2002
Location: USA
Posts: 1,852
Received 2 Votes on 2 Posts
They make PS testers for about $15. You can't really test a PC power supply with just a multi-meter, as the PS is linear. The reading you get with no load won't be the same as with a load. The testers have built in loading resisters to simulate a running system, and provide a more accurate assessment of the power supply.

You can probably take it to a local shop and they would test it for free, in the hopes that if it's bad, you will buy a new one while you are there.
Old 04-07-08, 03:20 PM
Join Date: Sep 2002
Location: welland ontario
Posts: 7,525
Received 237 Votes on 208 Posts
Pin outs are here. You need to short pin 14 to ground to turn the supply on.
Old 04-08-08, 11:40 AM
Join Date: Aug 2007
Posts: 304
Received 0 Votes on 0 Posts
The easiest way to do it yourself, is to just leave the old ps in the machine and plug the new one up to the motherboard and all the devices and power it on like normal. You'll know pretty quick if it's gonna work or not. Don't even waste your time testing power supplies.
Old 04-09-08, 02:31 AM
Banned. Rule And/Or Policy Violation
Join Date: Nov 2007
Posts: 504
Received 0 Votes on 0 Posts
And if there is a short in the system, your new PS is toast.

Check the motherboard for swollen capacitors. They look like miniature cans.
Old 04-09-08, 06:32 PM
XRing's Avatar
Join Date: Mar 2008
Location: Greater Boston
Posts: 103
Received 0 Votes on 0 Posts
The only Power supplies

that I have seen die was after the fan failed.

If you have a spare power supply, I would go ahead and install it. If the MB is really gone, there is likely not much reason to hang on to a backup supply for that PC.

A new PC (if you have to buy one) is going to come with it's own supply. More than likely, it will be different from your spare.. (Murphy's Law).

You might want to get a new with an extra drive bay, so you can retain your old HDD. I've done that a few times.
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: