How to Diagnose a PC Power Supply - Digital Web

When your computer or other electronics device fails to work, the first step in diagnosing the cause of the problem is testing the power supply. You should check to make sure that power is going into and coming out of the power supply. 

When alternating current enters the power supply unit it passes through a transformer, rectifier, smoothing circuit and voltage regulator to create unvarying low-voltage DC current.

How to Diagnose a PC Power Supply? Read this article to solve the problems with your powe supply.

 Things You'll Need

• Computer tower
• Volt Ohm Meter
• Power surge strip
• Small radio or electric fan

1. Check Power Coming in

   • Always connect a PC to house current through a surge protector.
     

     Make sure that the surge protector power cord is plugged into the house current. Check the surge strip by plugging a small radio or fan into one of the outlets and turning it on. If it comes on the strip is good.
   • Observe the power strip to see if the red flip switch is turned to the "On" position. If not turn it on and push the "Power" button on front of the computer tower. If the computer comes on the problem is solved.
   • Next unplug the computer power cord from the surge strip and then unplug it from the back of the tower. Look at the voltage selector switch on the back of the PC tower and make sure it is set to 115V.
   • Plug the power cord back into the tower and the surge strip. Push the "Power" button on the front of the tower and listen to see if the supply fan comes on. If the fan does not start, the power supply may need to be replaced.
   • Unplug the power cord from the surge strip. This will ensure that the computer is turned off for the next steps.

   Test the Power Supply

   • Plug the power cord back in to the surge strip but do not turn the computer on.
   • Remove the side panel to access the power supply.
     

     Remove the side panel on your tower by unscrewing the screws at the back edge of the panel and sliding the panel back and away.
   •  
     Check the power supply voltage at the CD/DVD power connector.
     

     Unplug the white power connector from the back of your CD/DVD player. This is where you will use a multimeter to check the output of the power supply.
   •  
     A multimeter measures voltage, current, and resistance.
     

     Set your multimeter to the next DC voltage setting higher than 12V. Push the power button on the front of the tower to turn on the PC and insert the black multimeter probe into the power connector on one of the black wires.
   • Insert the red probe into the power connector on the yellow wire. The meter should read between +10.5V to 12.9V. If the reading is different, then the power supply should be replaced.