Sparking (Arcing) Problem In LCD TV Repaired
This 32 inch LG LCD TV came in for repair with the complaint of no display but have sound. When a LCD TV have display problem it usually related to either the Inverter circuit or the CCFL backlight.
Sometimes it can also be due to bad power supply output DC voltages especially when there is a bulged filter cap at the secondary side.
Once the cover was removed, I could see the power supply/inverter, mainboard and T-con board. But the T-con board was was covered-see the photo below:
When I flipped over the power supply/inverter board I saw burnt marks (due to sparking) at the pin of the high voltage inverter transformer – see the two photos below:
What I did was to clean the burnt area and applied silicone glue to the inverter transformer pins. I did not expect it to run again. I just tested it to see if there is any sparking when the TV was On. To my surprise, the TV worked well and there was no longer any sparking at that inverter transformer area.
The screen came back normal without any distortion in the picture. I considered the repair was done since there was no further problem after running the set for long hour.
Conclusion- If after applying the silicone glue and there is still sparking (arcing) this means something is not right either with the inverter transformer itself or the incoming signal/voltage to the primary winding of the inverter transformer. This means, I may have to direct replace the inverter transformer and to retest it again. By the way Kent had just launched his new ebook on LED/LCD Panel and T-con board repair and you can click here to check it out.
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 in the below links:
https://jestineyong.com/lg-led-tv-repaired-with-no-picture-symptom/
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Waleed Rishmawi
August 24, 2019 at 1:19 pm
good job on the repair. that is a tough situation to deal with but you did a great job. have a blessed day
Albert van Bemmelen
August 24, 2019 at 2:41 pm
Pro repair which much resembles the way in which the HV cables of the ignition coil in Cars are protected with special spray against moisture to avoid sparking. Hopefully the CCFL backlight tube connections do not spark from bad contacts which also could cause black mainboard spots on the outputs. It happened in a HP 2509m monitor where only the backlight HV transformer to the bad connected CCFL tube that was sparking showed blackened pcb tracks. Which clearly over-heated the mainboard in that area.
Parasuraman
August 24, 2019 at 7:00 pm
Excellent service article throwing open, new areas of trouble and professional solutions.
Martin Bednarek
August 25, 2019 at 12:15 am
Interestingly the label indicates the TV originated in South Africa as it is printed in English and Afrikaans - a well-traveled set!
Tito Kanshulu
August 27, 2019 at 5:57 pm
Nice work Suranga, but I need clarification on the why applying silicone glue solved the whole problem. What is so special with this compound?
rajbir
October 15, 2019 at 6:12 am
i have no mail from last 2 months from your side please continue this , it is very useful for bigners. thanks.
Jestine Yong
October 15, 2019 at 11:02 am
Hi Rajbir,
Please resign up from the link in the below:
https://jestineyong.com/free-subscription/
Jestine