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LG 4K UHD, HDR 10, 49 INCH 2017 Model

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TV swaps every 2.1s between normal and flickering horizontal scanlines

I have inherited an unwanted LG 49UH610V TV. It exhibits an alternating visual error: half the time the image shows more-or-less normally, with only 2–3 single-pixel lines showing near the top of the display, and the other half of the time the image is unusable, showing numerous single-pixel horizontal lines across the display which contain image data offset by ~30 pixels. The display alternates between the two modes every 63–64 frames in the video I took, suggesting it switches every ~2.13 seconds.

I have tried all of the following without success:

  • Replacing only the T-con board with a salvaged unit from eBay. No change.
  • Replacing only the main board with a salvaged unit from eBay. No change.
  • Replacing both boards at the same time. No change.
  • Replacing the power supply–main board cable with the one included with the replacement mainboard. No change.
  • Replacing the main board–T-con board cable with the one included with the replacement mainboard. No change.
  • Disconnecting each of the T-con–display ribbon cables one at a time. Even worse image or none at all – I can't remember.
  • Covering various ranges of pins on the T-con–display ribbon cables with Kapton tape, as shown in two YouTube videos: A, B. Even worse image or none at all. ~2.1 second cycle did not go away.
  • Trying a different power cable (C7/C8 connector). No change.
  • Applying pressure while the TV is switched on to the long thin PCB at the base of the display that the two ribbon cables from the T-con board connect to. No change.

Based on the fact that I observe no change at all when swapping the T-con board, main board, and two cables mentioned earlier, these components must all working as intended. As far as I can tell, this leaves only the power supply board, the long thin PCB at the base of the display (like in this image), and the panel itself. I haven't taken apart the TV enough to confirm, but I believe the long thin PCB is soldered or otherwise bonded to the panel and therefore cannot be easily replaced. (On a side note, is there a name for this PCB)?

Does my conclusion sound accurate? Do you think this TV can be salvaged without buying a replacement panel?

Images and video are included below.

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Thanks to a reddit user, I was able to get the TV more-or-less working. Taping over the 8 pins on the inside of the left-hand side T-con-board-to-panel ribbon cable fixed the jittering. This cable is shown in the top-right corner of the second image in my original post.

Judging by the PCB traces, these eight pins connect to capacitors C480–C487 on the T-con board, then presumably to another component. The equivalent pins on the opposite connector are connected to surface pads marked by a box "B".

There is still one horizontal line showing near the top of the display, but it doesn't move or flicker. It appears to be displaying the green channel correctly, but the red and blue channels are absent. The line is not that noticeable, and the display is useable. I assume the real issue is in the board that is bonded to the panel and which the two ribbon cables from the T-con board connect to.

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bli will be eternally grateful.
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