In today’s disposable world, it is easier and less expensive to replace a failed power supply rather than attempt a repair. Modern desktop computers are in fact designed for ease in replacing this part.
If you have a standard-shaped desktop computer (commonly called a tower), then you should generally be able to purchase a compatible power supply at your local electronics store. If your computer has a specialized form factor (like the ones that are rather tiny), you may be forced to order a replacement from the manufacturer.
The Dell Exception:
The only exception to this basic rule applies to some older Dell computers; for a brief time Dell installed power supplies into their desktop units that looked exactly like a standard power supply but were wired in a completely different manner. Attempting to replace these power supplies with a standard power supply has disastrous consequences. As a result, whenever dealing with an older Dell system it is recommended that you contact Dell’s Technical Support at 1-877-293-1197 to verify that your system is compatible with a standard power supply.
Things You’ll Need:
Anti-static wrist strap
Replacement power supply
Notepad and pencil
Plastic cable ties
Digital Camera (recommended)
Place the anti-static wrist strap on your wrist and connect the clip to a metal portion of the computer to protect the device from stray static discharges while you work.
Disconnect the power cord from the back of the computer, as well as the monitor, keyboard, mouse, speakers, and any other peripherals that may be connected to the machine.
Move the computer to a smooth, well-lit work surface. Place the case laying on the side with the access panel facing up.
Remove the two or three screws securing the access panel to the case.
Slide the panel rearwards gently until it releases, then lift it away from the computer.
Locate the box near one corner with all of the wires coming out of it. This is your power supply. Take photographs with your digital camera to aid in replacing the wires during reassembly (recommended).
Trace out each and every wire coming from the power supply (you may have to cut a cable tie or two if the manufacturer has bundled them). Use the notepad and pencil to draw a basic diagram showing where the wires connect inside of the computer. This will help greatly during the reassembly process.
Disconnect the wires leading from the power supply to the optical and hard drives, and move them aside.
Disconnect the wires leading from the power supply to the motherboard. Make sure that you have noted every single connection to the motherboard on your notepad, and take pictures to aid your memory.
Disconnect any wires leading to fans or other areas within your computer. Most systems won’t need this step, but some will have a fan directly connected to the power supply.
Remove the four screws securing the power supply to the computer case. These will be located on the rear of the computer around the four corners of the power supply.
Gently lift the power supply out of the computer case, taking care not to drop it on the motherboard and components within.
Place the new power supply in place, and replace the four screws.
Connect the wires to the motherboard, using your photographs and diagrams to aid in proper placement.
Connect the power supply wires to the optical and hard drives, still using your diagrams and photographs for reference.
Connect any fans or other peripherals that you noted on your diagrams.
Organize the wires by using the cable ties to maximize airflow within the case. It is generally best to reconstruct the original tie arrangement and wire positioning that you noted in your diagrams and photographs.
Replace the access panel, and secure with the screws that were holding it in place.
Reconnect the power cord, monitor, mouse, keyboard, speakers and other peripheral cables that were originally attached to your computer.
Turn on your computer, and enjoy your new power supply!
Some techs prefer to test the power supply before mounting it into the case. To do this, connect all of the wires before mounting it inside of the case, plug in the power cord, and press the power button. Turn the power off as soon as you see that the computer is getting power to avoid endangering any components from a partial boot.
Most components in a computer are keyed to be inserted a certain way. Do not force any connectors as a result; if you feel resistance, stop and verify that the connector is oriented the correct way.
References:“Upgrading and Repairing PCs, 15th Edition;” Scott Mueller; 2004.