No Power In LED TV Solved
The complaint of this UNIC LED TV was no power. So the first thing to do is to remove the cover as seen from the photo below:
Once the cover was removed, I could clearly see two important circuit boards which is the power supply and the main board.
Some repair techs just call it as motherboard.
From visual inspection I saw one of the legs of the Thermistor was broken but the bottom joints were still intact. When I checked it using Ohmmeter it showed open circuit. By right it should show resistance between 3 to 30 Ohms depending on what part number of the Thermistor you are checking. The main fuse and corresponding components were checked to be good.
Since I do not have the exact part number, I used a replacement Thermistor from a junk LED TV power board. Once the replacement Thermistor is fixed and powered On, the power supply came back and I could see the display in the TV-see the photo below:
Conclusion- If you want to be good in electronics troubleshooting, your testing components has to be strong. If you can’t accurately or do not know how to test components then chances for you to solve an electronics problem will be very slim. All professional repairers know how to test and check components and they can check it very fast. If you want to know how to check components fast, i can recommend you to get Jestine Yong’s ebook Here.
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 previous post about fixing active speaker in the below link:
https://jestineyong.com/no-sound-in-mini-usb-subwoofer-repaired/
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Parasuraman S
March 25, 2017 at 1:08 pm
Good work!
Albert van Bemmelen
March 25, 2017 at 1:35 pm
Good job Suranga! Replacing bad components with spare parts is the only option left to do when no service manual is at hand to order new parts from. Which like in this case only can be done when the bad component still reveals its electrical characteristics.
Paul Cohen
March 25, 2017 at 9:05 pm
This is a trivial repair.
Please tell us more complex and surprising repair stories.
Paul
Mark
March 26, 2017 at 4:58 pm
Hey Suranga,
Even though this is a simple repair, it still helps us to learn the basics of electronic repair and how systems are put into place to protect the circuit from damage. Most likely it blew due to a voltage spike, possibly a lightning storm nearby. It is unusual that it didn't blow apart. Good to see that it did it's job!
Thanks for sharing.
zaheedi farjan
March 31, 2017 at 12:22 am
Hey plse advance elecronics ad theserepairs r for begginers not even for tech each time wr just cant get visual repairs
Regards zaheedi
Ulises Aguilar Pazzani
April 1, 2017 at 11:36 am
Mr Bandara , good after noon Sir, great fix good eays
Chaminda
April 4, 2017 at 2:54 am
Hi Mr.Suranga...
Don't you have an idea to conduct Electronic classes in Sri Lanka
If it is so please be good enough to inform me
Chaminda
Colombo
reza
April 12, 2017 at 1:16 pm
Hi mr Suranga Bandara
u are very good repairman
thank u