How to Remove And Replace An ATX Power Supply Unit (PSU) On Your Computer
ll wires and a standard desktop computer. This will be relevant for people who are upgrading their existing PSU or replacing This article describes the steps required to replace an ATX Power Supply Unit (PSU) on a blown PSU as the procedure in both cases is identical.
Replacing a PSU is not a complicated procedure to perform and we have included a few very handy tips that help make the process a simple task, even for a beginner.
Safety Advice
Even when disconnected from the mains, the internal capacitors inside a power supply unit can still hold a lethal charge so it is important to never dismantle a PSU or insert any objects such as a screwdriver into any gaps in the outer casing of the unit.
Equipment Needed
To follow the steps in this article you will need a Philips screwdriver, a digital camera and an anti-static wristband.
1) Unplug PC & Remove Side Panel
The first step is to disconnect the PC from the mains, lay the computer on its side on a steady surface and remove the main side panel so that you have a clear view of the internal components (the side panel will usually slide off once two small screws at the back have been removed).
2) Photograph The Inside Of The PC
This is a very useful tip for any beginner as it will provide a point of reference when you come to fitting a new power supply unit. With the flash enabled take a clear photo of the internal layout of the PC so that you can clearly see the position of aconnectors inside (if necessary take several photos from different angles).
3) Attach Anti-static Wristband and unplug connectors
The next step will involve you unplugging the various connectors from the PSU and therefore we recommend wearing an antistatic wristband to protect components from ESD (electrostatic discharge). You will be able to easily identify the PSU because it will be a square box located at the top of the case with a rather untidy mass of wires protruding from it.
You will notice that the wires are grouped together into small bunches which branch off in different directions and connect to various locations inside the computer. Take your time and slowly trace each bunch of wires to the end where they will be plugged into another component with a simple plastic connector of variable shape and size. Unplug this connector and repeat this procedure for all wires protruding from the PSU. Once you have done this you will have now disconnected the PSU from all of the components within the computer.
4) Remove PSU.
Now that the PSU is no longer connected to any other component inside the PC it can be easily be removed by unscrewing the four Philips screws located on the back of the computer at the top – there will be one for each corner of the PSU (N.B. Keep the screws handy as you will need these to fit the new PSU). You will not be able to remove the old PSU.
5) Install Replacement PSU
Your new PSU should be the same physical dimensions and therefore all you will need to do is position it into the case at the same orientation as the previous PSU, make sure it is line up with the four screw holes on the rear of the PC and then using the four screws you removed in step 3, lock the new PSU into place.
6) Connect PSU to All Components
Now that you have your new PSU in place it will be necessary to connect all of the wires to their respective components in exactly the same manner that the previous PSU was connected.
You should notice that the wires on your new PSU will correspond to the wires on your old PSU and therefore there will be the same types of various connectors present. You can work out the correct destination for each set of wires by matching the connector with the corresponding connection on each component inside you computer but if you followed the advice of step 2 and photographed the inside of your case you should now have an excellent point of reference from which to begin connecting the PSU.
Once you have connected the PSU to all components, you may find that you have several small connectors which are spare – if this is the case don’t worry, this is exactly what they are, i.e. spare. The best thing to do is use a cable tidy or elastic band to neaten any spare wires and keep them out the way of other components inside the computer.
7) Final System Check
Before you re-fit the side of the PC case double check every connection from the PSU to make sure all of the connections are secure (the largest connector which enters the motherboard can be quite stiff and may require a firm push to make sure it is sitting flush). Also it is very important to check the voltage switch on the back of the PSU as these units can be set to either 230V or 115V so make sure it is set to the correct setting for your geographic location (if unsure consult the documentation of the PSU). You can now re-fit the side of the PC case.
Power On
Ensure the power switch on the PSU is set to the on position then attach the kettle lead to the mains and power on your computer. If all goes well the system should power on normally and begin loading your operating system. Check that all devices are working properly (DVD Drive, Card Readers etc). If the system does not power on correctly you will need to unplug the PC from the mains, remove the case and double check every connection again – the chances are you have missed something (remember to use the photos you took earlier for reference).
Final Thoughts
If you followed the steps above and have successfully completed the procedure then congratulations you have just managed to complete a repair that would cost you in the region of 30-50 in a computer repair shop and gained some valuable working knowledge of the components inside your computer that may benefit you in the future
