What are the steps to test a power supply unit for faults?

Yes you will need to have the right tools to get this done, as with other job. Not having the right tools, make the jobs a lot harder and more time consuming. Also, try to setup on a table where you can have enough space to lay down the tools so you can get to work. Try to have a few screwdriver sets, this way you can have the right screwdrive for the type of screw. Also a multimeter so you can test voltage. But prepartion is very important with anything that we do.

Working on live power supply units is life-threatening and should only be carried out by trained specialists. An isolating transformer should be used, a regulating transformer is also helpful. A distinction is made between longitudinally regulated and switched-mode power supply units. Power supply units can cause various problems, short circuits, insufficient power, hum, etc. Sometimes it is sufficient to check components in the powerless power supply for open circuit or short circuit with an analog ohm meter. A general guide to repairing power supplies is not so easy to explain and goes beyond the scope of this post, as different circuits and components are used, and the use of an oscilloscope is also helpful.

Visual Inspection , Use a Multimeter, Paperclip Test Optional for ATX PSUs, Load Test, Check for Noise or Coil Whine, Thermal Testing, Inspect Cables and Connections, Testing with Another PSU if possible.

Before removing the PSU I would say to look at where the PSU is connecting. Assuming that this is going to a motherboard, try to take a look at the lights at the motherboard. This can give you an idea if any lights which could have codes for the type of issue. Another thing is that you can more or less see if it's passing power just by looking at the lights. If you don't see any lights or anything like that, than I would just remove the PSU. Remember that now for this step, to unplug the power cables so you can begin the process of removing it.

From a desktop removing a PSU is a simple a task as there is when it comes to computers. Now from a laptop there are a lot more complicated when it comes to getting to the PSU. However, disconnecting the connections from the MB is fairly simple. Remember you will need to remove the power connectors to the devices that are powered like HD's, DVD drives, etc. Then remove the screws that are holding the PSU in place on the device. Putting them back is just as simple since it's hardly impossible to connect the connectors to the MB's since they only fit in one place. Depending on the form factor can require removal of lots of components. Try to organize your screws to ensure the right screws go back in the right place. A diagram could help.

Once the PSU has been safely removed, now you can begin to test it. But first, try to look at it first and try to inspect there. Yes most likely you won't be able to fully resolve the issue by looking at it but again, this could give you some clues or ideas. If you see a side that is a little burnt or smokey, that could be a sign. If you see that is smoked, maybe for sure that unit is no good. After doing an inspection, now you can put the multimeter on and see what it reads. That will give you a clear indication if the unit is really bad or not.

Na etapa 3, que é as verifica??es de tens?es, caso n?o tenham o esquema elétrico, poderá ser usado o data sheet dos componentes para determinar se as tens?es medidas est?o realmente corretas ou n?o. Além do data sheet, é sempre bom conhecer a lei de Ohm e as leis de Kirchhoff que comp?em as leis das correntes e das tens?es!

Once you tested the unit and are ready to replaced with a good one, now you can install a good one. Try to following the same steps that you did when you removed it but in reverse. I like to even try to put the same screws back into the same hole it came out from. This way as you're putting in the new, you want to try to keep everything the same as much as you can.

In my experience, this is something that is not too complicated to do. Just remember to have the right tools in order to get the job complete. Also, because you are dealing with components that deal with electricity, always make sure to take safety precautions, no matter how simple and small they are.

As per my understanding and experience.before performing any supply function .need to visualise the condition of PSU than Check for any bulging or leaking capacitors, burnt components, or loose connections. Verify that the cooling fan is operational and free from obstructions.