Three Bad Components Found In Power Adapter
Power supply repair and a good lesson to learn
A customer who owns a store nearby brought a power supply for repair. There was no sign of life in it, it was completely dead.
It is a China made power supply but it was the original one that came with the printer when he first bought it.
This is the layout of the power supply and the first thing I checked was the fuse.
It was blown and that means something is wrong in the nearby components such as bridge rectifier, capacitor or the main Mosfet.
It is a 3.15 amp fuse. I roughly checked the surround components but strangely nothing was shorted out. I did not like the sound of that so instead of putting a new fuse, I added a light bulb to the main connection of the fuse and powered it up.
And as expected, the light bulb was shinny bright indicating a short somewhere and that did not make sense.
I decided to take every component off board and test and hope for the best. the first thing I came across was the bridge rectifier and this time it showed two way reading across the AC and the ( -) side on that part.
The second component I came across was the main capacitor. It tested fine before but now it was testing only 1.7 UF out of 68 UF and that was really bad.
Because of the work load I was getting in the shop that week, I was not doing things the way it should be when it comes to testing. I want it done the fast way so I can fix everything in no time and that is a lesson to be learned here. Never ever rush through when it comes to testing and repairing electronics.
Anyway, I replaced all these bad components and before I added the fuse I checked with the light bulb trick once again to make sure.
This time, the light bulb stayed dim and the LED light of the power supply was on as well. Now it was safe to replace the fuse and get it over with.
This article was prepared for you by Waleed Rishmawi, one of our ‘Master Authors’ and currently working in the Bethlehem area of Palestine repairing electrical and electronic equipment.
P.S- Do you know of any your friends who would benefit from this content that you are reading now? If so, forward this website to your friends or you can invite your friends to subscribe to my newsletter for free in this Link.
Note: You can check his previous repair articles in the link below: