A power supply (PSU) is one of the most reliable components in your computer.
only one moving part and a design to compensate for heat the
out last the rest of your computer. For the most part the only point of failure
in a PSU is the cooling fan.
PSU failure is catastrophic, by that I mean it is either working or not
working. There is no post or beep code, nada, the computer will not start. For
trouble shooting prior to repair see the Info page, here we are going to look at
changing a dead PSU.
Disconnect the electrical cord! When doing power supply repairs
You will have to open the case to do the following procedures. You may have to
take the psu out before you even find the new one, if you have a
digital camera take some pictures of the interior of the computer, you can refer
to the pictures when you reassemble it, especially if it takes a long time to
get the new part.
If you have a proprietary computer then you can check the manufacture's web site for the
correct PSU for your computer by make and model. For those of us that have
clone, home built, or BIG computers we will have to check the PSU for
information before we purchase a new one. Most psu have a label on them that give you the wattage and maybe a manufacture with a part number.
The main thing we are looking for is the wattage. If you have to replace a PSU because of failure I suggest you go to a higher wattage PSU.
Next you want to look at the connectors. The connectors are two types, the motherboard power connector and the accessories power connectors (connectors for
drives, fans, etc.). Some ATX PSUs also come with the SATA power
connectors. The main power connector will be the AT (almost obsolete) or ATX,
the AT has 20 pins, the ATX has 24 of pins. Next you need to know the dimensions
of the PSU, if you purchase a PSU that is to big to fit into
the bay the old one came out of you will have to return it and get the correct
A picture is worth a thousand words. If you can get to the web, search for
a PSU and find one that looks close to what you have, then read the item
description, check the cables, do they look the same?
Ok, got the new part, set it beside the old one, do they match up? Some power
supplies have tabs that lock into the bay where the PSU is installed.
Everything OK? Do you remember how it came apart? No? check your pictures!!
Reassemble the computer, the psu
will not need a burn in in case you are
All back together?
Check your connections one more time, tug on them, they
should not come out of the sockets. Check for loose or dropped parts. tools,
screws! All good, put the case cover back on,
reconnect the external cables, turn it on.
Good to go?
No? Disconnect the power cord!!
Check your work something is going to ground.
Check all the connections, compare
your work with the pictures you took before disassembling the computer. Check
the memory and any card in the slots, one of them may have been bumped and came
partially out of the slot.