I’d stopped repairing ATX power supply several years back due to the new one cost very cheap. It’s not worth to correct it since the spare parts sometimes were much more expensive than obtaining a new power supply. Searching for ATX power supply spare parts wasn’t easy as many 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 as a result of we truly need time and energy to know the way all these different designed power supply work.
Some of the power supply designs were using the PWM IC (UC3842) and power FET, some utilize the double transistors while some use only a single power IC in the primary side. Because of the manufacturers wants the look to be changed to compact size, many secondary or even primary power supply circuit were build right into a modular board (smaller board). This made troubleshooting even more challenging because often the meter’s probe can’t reach to the testing point.
The real reason I’d stopped repairing ATX power supply was the profit margin. In the event that you charge to high the customers rather buy a new unit with twelve months warranty given. In the event that you charge too low, you could result in the losing side because of the FFPOWER components replaced, electricity and etc. In the event that you charge reasonable, the profit margin gained can’t even cover your own time spent on troubleshooting it. I’m here not to 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 you might go ahead to repair it.
Okay back to this article, among 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 the one that suits his customer’s CPU. He wanted a power supply that is either same size or smaller then a original one with same or more specification but all he could find was a typical size power supply!
As a favors to my customer, I would do my best to simply help him to repair the ATX power supply. When the ability supply was turn on, measurements were taken. The outcome were over voltage. The 12 volts line shot around 13 + volt and the 5 volts line became 5.6 volts. Following the casing was removed, I came across the inside was very dirty and I used a hoover and a comb to clean off the dirt. Then I saw four filter electrolytic capacitors had bulged at the very top casing.
You may already know, we as electronic repairers can’t just see things at only 1 side; we’ve to see one other sides too. What I mean was, try to see if there are any suspicious components that contributed to the failure of the ability supply such as for example broken components, dry joints, loose connection, decay glue and etc before start checking the suspected area.
What I saw was at the primary side there have been some components covered with decayed glue as observed in the picture. I need certainly to carefully remove it by scrapping off the layers of the decayed glue while preserving the outer layers of the components. Once it was 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, be sure you check the fan too because some power supply failure was due to heat the effect of a faulty fan. The objective of the fan would be to suck out all the warmth generated by the components inside the ability supply. For the fan to run smooth, you can service it with a Philips oil base spray as shown in the photo.
After the four electrolytic capacitors were replaced and the decayed glue removed, I then need certainly to plug it right into a junk motherboard along with a hard disk to check the performance of the ATX power supply and measure most of its output voltages. It looks like the output voltages were back to normal. Once everything is okay I then test it in a functional CPU to check on for the display.
The reason why I test it with a junk motherboard first as an easy way not to cause my good motherboard to lose their freshness just in case if the output voltages is still very high. Better safe than regret later. Incidentally you can’t test a power supply without load otherwise it may turned on for some time and then shut down. If you do not have a junk motherboard you can always at the very least connect a drive and a line jumper to its connector to switch on the ATX power supply.