I had stopped repairing ATX power supply a long time back as a result of new one cost very cheap. It’s not worth to repair it as the spare parts sometimes were much more costly than getting a new power supply. Looking for ATX power supply spare parts was not easy as many of them you can’t even see them on the internet. Not just that, many complicated and different created by power supply manufacturers had eaten up our precious troubleshooting time too because of we truly need time to understand how each one of these different designed power supply work.
A few of the power supply designs were utilizing the PWM IC (UC3842) and power FET, some use the double transistors although some use just a single power IC in the principal side. Because of the manufacturers wants the style to be converted to 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 often the meter’s probe can’t reach to the testing point.
The actual reasons why I had stopped repairing CN505 power station ATX power supply was the profit margin. In the event that you charge to high the customers rather purchase a new unit with one year warranty given. In the event that you charge too low, you may result in the losing side because of the components replaced, electricity and etc. In the event that you charge reasonable, the profit margin gained can’t even cover your own time allocated to troubleshooting it. I’m here to not discourage you to prevent repairing ATX power supply, however when you yourself have the time, have contacts getting cheap power supply components, accessible many power supply schematic diagrams and etc then you might proceed to fix it.
Okay back to this article, certainly one of my customers had asked me to fix his ATX power supply. I told him to acquire a new one (since it had been very cheap) but he explained he couldn’t find one that suits his customer’s CPU. He wanted a power that is either same size or smaller then the original one with same or maybe more specification but all he may find was a standard size power supply!
As a favors to my customer, I’d do my best to simply help him to fix the ATX power supply. When the energy supply was activate, measurements were taken. The results were over voltage. The 12 volts line shot as much as 13 + volt and the 5 volts line became 5.6 volts. After the casing was removed, I found the interior was very dirty and I used a hoover and a comb to wash off the dirt. Then I saw four filter electrolytic capacitors had bulged at the top casing.
As you know, we as electronic repairers can’t just see things at only 1 side; we’ve to see one other sides too. What I am talking about was, attempt to see if you will find any suspicious components that contributed to the failure of the energy supply such as for instance broken components, dry joints, loose connection, decay glue and etc before start checking the suspected area.
What I saw was at the principal side there have been some components covered with decayed glue as noticed in the picture. I have to carefully eliminate it by scrapping off the layers of the decayed glue while preserving the outer layers of the components. Once it had been done, I clean it with the Thinner solution. Decayed glue might cause serious or intermittent problem in electronic equipment because it can be conductive.
In the event that you repair any ATX power supply, ensure you check the fan too because some power supply failure was due to heat the result of a faulty fan. The purpose of the fan is always to suck out all the warmth generated by the components inside the energy supply. For the fan to perform smooth, you are able to service it with a Philips oil base spray as shown in the photo.
Once the four electrolytic capacitors were replaced and the decayed glue removed, I then have to plug it into a junk motherboard as well as a hard drive to try the performance of the ATX power supply and measure each of its output voltages. It appears as though the output voltages were back to normal. Once everything is okay I then test it in a working CPU to check for the display.
The reason why I test it with a junk motherboard first as a way to not cause my good motherboard to go south just in case if the output voltages is still very high. Better safe than regret later. Incidentally you can’t test a power without load otherwise it may fired up for a time and then shut down. If you may not have a junk motherboard you are able to always at least connect a hard drive and a line jumper to its connector to turn on the ATX power supply.