Modification Of LED TV SMPS
This BG 24 Inch LED TV came in with the complaint of no power. Generally no power symptom mostly are cause by the failure in the power supply board. It can also cause by failure of the mainboard because the power LED signal is coming from the mainboard MCU IC. No matter which board failure, I still need to open up the cover and to troubleshoot it. Once the cover was opened, I focused on the power board first.
Visual inspection did not see any unusual problem be it on the components or the wiring cables.
The main fuse was tested good thus I checked on the main filter capacitor and there was 325 volt present at the two pins. I can actually go straight to check on the output DC voltages at the connector but somehow wanted to show to you how to measure the main filter capacitor voltage.
I further checked on the surrounding components in the primary power section and all components checked to be good.
I suspected it was the power IC that have issue but the problem is the part number of the power IC was removed. It is slightly difficult to know each of the pin function especially to the beginners.
In order to remove the guesswork if the power IC is the cause of the problem or not, I installed the power module (5 pins) to test it out and see if the power will come back or not.
I connected to all the wires to the 5 important points as shown in the diagram below. Sorry if the diagram is blur.
Below is the photo of a successfully installed power module and I tightened the power module to the nearest casing to dissipate the heat. See the two photos below:
Once the power was turned On, the picture immediately appeared.
This has proof that indeed the original power IC got problem.
Conclusion- With the external power module installed and the TV worked, this has save me tremendous amount of time. I do not need to know the exact part number of the power IC. The installation time was fast provided you know where to solder the 5 points. If you have difficulty in understanding how I have fixed this power module, I suggest that you get Jestine Yong’s ebook on Small SMPS Modification. With three real cases, clear photos and explanation, I’m sure you could easily follow his step by step methods and have an easy success modification like what I have done in this article. All the best to you!
This article was prepared for you by Suranga Bandara who owns an Electronics repair shop in Anuradapura, Sri Lanka.
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Note: You may check out his previous post about Olik Amplifier No Sound In Right Channel Repair