Flashing Horizontal Stripes on LED TV LG 42LA691S: Post-Warranty Screen Issues & Solutions

Hello all
I have had a LG 42LA691S 3D / SmartTV / FullHD / 400Hz TV for two years and 5 days. The television was covered by a two-year warranty and three days after it had expired, problems started. Namely, turning on the TV on the first day after the warranty expired, vertical stripes appeared on the entire screen. There was sound and vertical colored stripes flickered across the black screen. After turning off the power for a while, the TV turned on normally and played all day without problems. On the second day I turned on the TV and it started up normally. in the afternoon of the same day when turning on the problem returned and again after turning off and on everything went back to normal. On the third day, the television turned on normally until the air humidity in the house did not exceed 65%. Then the image seemed to crop and jump slightly in different directions. I turned it off with the remote, turned it on and there were stripes all over the screen. After turning off the power and turning on, the problem disappeared for 2-3 hours and then it repeated several times. In the evening I turned on the TV and everything was fine. After an hour of watching, I noticed that 2-3 horizontal stripes started flashing at a height of about 10-15 cm from the bottom edge of the matrix. The stripes are horizontal across the screen, each approximately 1mm wide. I noticed that they are blinking constantly in one place and at regular intervals. they appear for 2-3 seconds and then disappear for 2-3 seconds and so on. Turning the TV off and on does not give anything anymore and the stripes appear immediately after turning on the TV. In the attachment he adds photos and a link to the video (https://youtu.be/8eW--pyurOk) how it looks. I unscrewed the back cover of the TV and with the naked eye did not notice any overheated or damaged elements on the plates. Everything looks rather normal. I also checked the connections and the cleanliness of all connectors and tapes as if everything looks good. I thought maybe something related to dampness, so I treated all the elements with a dryer for a good hour without any results :-(

I am afraid that the matrix may sit down, but maybe someone of you will tell you what the reason for this situation may be. Due to the fact that the TV has a 3D matrix, matrices are quite expensive and I would not be inclined to replace it. If any electronics fell, it would be better because these elements are not very expensive. Please give me a hint if you can do something about it yourself.

Thanks in advance for any suggestions
best regards
Andrew

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Link to the video with the signs of the LG 42LA691s defect - https://youtu.be/8eW--pyurOk

Hello. Did you deal with this defect in the TV and what was the cause of the stripes, because I have the same defect.
I would like an answer.

Hello. Such similar stripes may appear as on the motherboard or t-con, ie you have bga chips. Lead-free tin technology is what forces the consumer, just like you, that usually such miracles happen shortly after the warranty period.
As for repair. If you are familiar with a really good service with bga ball changing machines, you will find the solution to your problem there. Let them exchange the lead balls under the process and memories for good and that's it.
I was just not having access to such a service, so I risked a repair at home. For me, the album had as many as 10 Bga chips. I undressed the tv gently. I initially dusted the tiles and washed with technical alcohol. Then I covered all plastic elements with Kapstan tape, connectors and even smd electrolyte capacitors. Successively I smeared a good FLX RMA223 around all the bga systems so that they would flow into the systems.
I heated the oven to about 170c and placed the protected electronics in my own original frame halfway up the oven shelves. I slowly increased the temperature and controlled it with a pyrometer so that the plate at and on the systems reached a temperature of about 220 225 degrees. I heated it for about 25 minutes and then, without touching it, I turned off the oven and let the plate cool down to room temperature.
Then everything was gently cleaned of the flux and installed in the chasis tv.

Started up without straps. I keep my fingers crossed that the repair will be effective for longer. I didn't find functional electronics for my Sony TV anywhere, so I had to risk getting rid of the strip defect. For me, the symptom of the bars indicated the electronics because they could move when I changed the TV operating mode regarding the screen refresh rate. And so much good.