I had stopped repairing ATX power supply many years back due to the new one cost very cheap. It’s not worth to repair it because the spare parts sometimes were much more expensive than getting a new power supply. Searching for ATX power supply spare parts was not easy as many of them you can’t even find them on the internet. Not only that, many complicated and different designed by power supply manufacturers had eaten up our precious troubleshooting time too because of we need time to understand how all these different designed power supply work.
Some of the power supply designs were using the PWM IC (UC3842) and power FET, some use the double transistors while some use only a single power IC in the primary side. Because of the manufacturers wants the design to be made into compact size, many secondary or even primary power supply circuit were build into a modular board (smaller board). This made troubleshooting even more difficult because many times the meter’s probe can’t reach to the testing point.
The real reason why I had stopped repairing ATX power supply was the profit margin. If you charge to high the customers rather buy a new unit with one year warranty given. If you charge too low, you may end up in the losing side because of the components replaced, electricity and etc. If you charge reasonable, the profit margin gained can’t even cover your time spent on troubleshooting it. I’m here not to discourage you to stop repairing ATX power supply, however if you have the time, have contacts getting cheap power supply components, easy to access many power supply schematic diagrams and etc then you may go ahead to repair it.
Okay back to the article, one of my customers had asked me to repair his ATX power supply. I told him to get a new one (since it was very cheap) but he said he couldn’t find one that suits his customer’s CPU. He wanted a power supply that is either same size or smaller then the original one with same or higher specification but all he could find was a standard size power supply!