Desktop power supply computer troubleshooting

Thread Starter

satouri abdellwahed

Joined Aug 23, 2018
3
Hello,
I'm new in world of electronics, i want to learn how to test elctronic circuit to repair them. I have a problem in the power supply of my computer , i tested it on two computers and i had the same result : to open my computer i should push many times on power button , and sometimes suddenly the computer stop working , i tested the voltage of cables i find 10.4 on yellow and -9.16 on blue : i verified that's less than standards , but i don't know how to repair , (there's no inflated capacitor).

 
Last edited by a moderator:

LesJones

Joined Jan 8, 2017
2,665
Switch mode power supplies are not the place to START learning electronics. They are potentialy dangerous to work on as the primary side is all at mains potential. You can't connect your oscilloscope to the primary side unless the power supply is isolated from the mains with an isolating transformer. There is a chance that replacing all the electrolytic capacitors may fix your problem but is probably cheaper to buy a new power supply. Start learning electronics (Assuming that you have learned basic electrical theory like ohms law, power calculations and how inductors, capacitors, transformers and transistors work,) by working first working with battery powered circuits then move on to things that use linear power supplies that are isolated from the mains with a transformer. You will find this type of power supply in older equipment.

Les.
 

Thread Starter

satouri abdellwahed

Joined Aug 23, 2018
3
Switch mode power supplies are not the place to START learning electronics. They are potentialy dangerous to work on as the primary side is all at mains potential. You can't connect your oscilloscope to the primary side unless the power supply is isolated from the mains with an isolating transformer. There is a chance that replacing all the electrolytic capacitors may fix your problem but is probably cheaper to buy a new power supply. Start learning electronics (Assuming that you have learned basic electrical theory like ohms law, power calculations and how inductors, capacitors, transformers and transistors work,) by working first working with battery powered circuits then move on to things that use linear power supplies that are isolated from the mains with a transformer. You will find this type of power supply in older equipment.

Les.
Thank you so much for all these advices , but i need to repair this one , as i know probably most of troubles depend of capacitors but as you see all of them seems on good condition , have you an idea , probably this problem depend of what ?
 

dendad

Joined Feb 20, 2016
3,564
I second LesJones' comments.
This is NOT the way to start learning electronics. Power supplies like this are very dangerous. Please take the advice given as it is for your benefit. A replacement supply is cheap, often another can be found for free out of an old PC too.
This one looks to have overheated so there may be lots of parts that need replacing.
It also looks pretty dirty. Try to run your PC in a cleaner place, and off the floor to help limit dust pickup.
And to repeat, DO NOT start your electronic adventure this way. If you insist on ignoring good advice, you stand a fair chance of having a real short electronics career. And that would be a shame. A power supply is just not worth that!
 

AlbertHall

Joined Jun 4, 2014
10,022
Switch mode power supplies are not the place to START learning electronics. They are potentialy dangerous to work on as the primary side is all at mains potential.
Very much agree.
Such supplies are difficult enough to repair even with lots of experience and a good schematic diagram. I spent quite a few years in a job which involved repairing such supplies.
 

Reloadron

Joined Jan 15, 2015
5,504
First, I have to agree with everyone else in that working on a PC ATX form factor PSU is not a good place to start and can be dangerous, especially for the inexperienced person learning.

Next, be it a computer PSU or any other electrical or electronic circuit one needs to know how the circuit actually works and understand the circuit. Later computer PSUs should have a 5 Volt SB (Stand By) always present and are started using a PS_ON command from the PC they also have other lines on the main PSU to Motherboard connector and you need to know what each line does and at what point in time it should do it. Too many things to list which need to happen in a sequence for the PSU to start.

You can start to study up on computer PSUs but really will need a good foundation to understand their operation. I do not see a project like this as a beginner project. Additionally you are not likely to find a good schematic of exactly what you have to work from and several pieces of general purpose test equipment needed to troubleshoot.

Ron
 

Thread Starter

satouri abdellwahed

Joined Aug 23, 2018
3
thank you for all precious advices, but i think in many cases we have simple verifications that can solve the problem , for example in my case , i found two resistors had one pins broken, so i soldered them , and fortunately the problem seems resolved
 

dendad

Joined Feb 20, 2016
3,564
That's good :)
But all the above advice still stands.
Electronics is a great hobby so I would encourage you to learn as much as you can. The field is so wide now, so many things to play with.
 

dl324

Joined Mar 30, 2015
10,944
thank you for all precious advices, but i think in many cases we have simple verifications that can solve the problem , for example in my case , i found two resistors had one pins broken, so i soldered them , and fortunately the problem seems resolved
They're so inexpensive, it's not worth the bother to try to repair.
 
Top