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Video:How to Test a Power Supply

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Power failures happen frequently with computers; however, if you know how to test your power supply, it doesn't have to be a stressful situation. In this about.com video, learn how to test a computer power supply.See Transcript

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Transcript:How to Test a Power Supply

Hi I'm Evan Stein from CMIT Solutions, and I'm here for About.com to show you how to test the power supply. 

If you press the power button on your computer and nothing happens, the first thing you should do is not panic. Most likely your date is fine, and the power supply on your computer has failed or is having problems. 

Use Multi-Meter and Piece of Wire to Test Power Supply

To test your power supply, you're going to need a multi meter and a small piece of wire. The first thing you want to do is make sure you've unplugged your computer.

Disconnect Components

Open the case and remove all of the components, the hard drive and the DVD drive.  This is the power supply. Once you've disconnected all of the components, all of the wires from the power supply should be free with the exception of this: the 24-pin motherboard connector. 

Disconnect the connector from the motherboard, and you're going to need the small wire to jump pins 15 and 16. Now the way to identify pins 15 and 16 are to look for a green wire and a black wire next to each other.

Jump Pins, and Plug Computer Back In

It's 12 pins on a side. So, counting from here, which would be pin 13, the oranges are 13, the blue is 14, that black is pin 15, and that green is pin 16. I want to take that small wire and jump pins 15 and 16 like this. Once you've got those pins jumped, plug the computer back in, we're now ready to test the voltage. 

ATX 24-pin 12-Volt Power Connector

You're going to want to find a pin out for the ATX 24-pin 12-volt power connector.  And you can find that on About.com. That's this.  That pin out will tell you which of these ports are ground, and which of these ports are carrying voltage.  The two oranges are pins 1 and 2.  The third pin I know is ground.  I'm going to take my black from the multi-meter, ground that on pin 3, and I'm going to test the voltage of pin 1, which is coming in at 3.4, right in the acceptable range.  Testing pin2, and the multimeter shows again, 3.4.  Pin 4 is a 5-volt pin, and the multi meter shows 5.12 volts, which is also in the acceptable range. 

Finish testing your power supply by going pin to pin with the red connector and comparing the voltage to the outputs that are listed on that pin out for the 24 pin, 12 volt power connector.  And that's how you test a power supply. 

For more information, visit About.com.
 

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