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LED TV Repair- Cheap Replacement Parts
The complaint of this Changhong LED Screen TV was no display (no picture) and in standby mode (red color LED light). The usual problem for a standby LED can be due to bad mainboard or power supply whether it is from Samsung, Philips, Vizio, Pnasonic, Toshiba, Sony, LG, Sharp or Coby brand. The mainboard must receive a stable standby 5 volt from the power supply in order for the MCU and memory ICs to work. If without the 5 volt, the mainboard is totally dead.
If the 5 volt dc supply is improper or unstable, the MCU IC will not send an On signal to turn on the full power and the standby light will remain red and will not turn to green or white. Sometimes the power LED will have flashing light too. So the first thing you need to check is to make sure the power supply is producing a good and stable 5 volt dc supply. As usual, in order to troubleshoot the circuit board, one has to open up the set cover. Below is the photo of the mainboard and power supply board once the cover was removed.
Just by looking at the electrolytic capacitors on the power supply board, we can know that these capacitors were causing the standby problems. It was not one capacitor bulged but 4 of them! Look at the two photos below:
I did not even measure the standby 5 volt voltage because from experience, I can tell that the cause of the problem was surely these bulged capacitors. Replacing these parts was easy, just solder out the capacitors and replace with the same value of capacitance, same voltage and same temperature. These capacitors does not cost much and many times you can use a salvaged capacitors from a junk board.
Just make sure those capacitors are the branded one so that it will have a longer live span as compare to those non branded capacitors which do not last especially working under hot environment. I have tested other capacitors in the power supply and all seems to be within spec so I never replace them.
Once the capacitors were replaced and powered On, the blue screen immediately appeared which prove that indeed it was just the capacitors problem only. It was an easy job and I have earned some profits from this 25 minutes work. Please give me a like in the below if you found this article useful. Thank you.
This article was prepared for you by Suranga Bandara who owns an Electronics shop in Anuradapura, Sri Lanka.
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