LG 55UC970V-ZA: vertical bands/lines appear every ~2 seconds

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Joao Martins @joaomartin60969

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Posted: 5 days agoJan 10, 2026

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LG 55UC970V-ZA: vertical bands/lines appear every ~2 seconds

Hi all,
I have an LG 55UC970V-ZA (around 10 years old). The picture is normal right after power-on, but after ~2 seconds vertical bands/lines appear across the screen. Then it clears again, and the issue repeats in a cycle (roughly every 2 seconds).

Symptom (repeatable):
- After power-on, the picture is normal for about ~2 seconds.
- Then vertical bands/lines appear across much of the screen.
- It happens on everything, including the LG boot logo and the TV’s own menus/OSD, built-in apps, and all HDMI inputs.
- Power-cycling (unplugged 10–15 minutes) didn’t fix it.
- No obvious physical impact damage to the panel (no cracks), and the issue is present before any external device matters.

What I think this rules out:
- HDMI cable / source device / signal issue (because it shows on the boot logo/OSD).

ChatGPT-based symptom triage (I know this isn’t a real diagnosis, sharing for context):
“Because the vertical bands appear on the boot logo and start after ~2 seconds, the fault is likely in the internal display chain (T-CON / display board / ribbons / power rails feeding the panel) or panel TAB/COF bonding; main board is less likely.”

ChatGPT suggested approximate likelihoods (again, just a triage guess):
- T-CON / display drive / ribbons / power rails: ~55–70%
- Panel TAB/COF bonding (panel failure): ~20–35%
- Main board: ~5–15%

Parts info I found online (not yet confirmed on my unit; I have NOT opened it):
- Panel reported as LC550CQN(FG)(F1)
- T-CON reported as 6870C-0524A / 6871L-3754A (often referenced with “V14 TM120”, but I understand revisions matter)

Questions for experienced TV repair folks:
1) Does “vertical lines even on boot logo/OSD” + “OK for ~2 seconds then bands” usually point more to T-CON/drive/power-rail instability, or does it still scream panel TAB/COF to you?
2) What safe, non-invasive tests would you recommend to separate T-CON vs panel vs power before I spend money?
(e.g., built-in picture test if available; anything I can do without opening the set)
3) For a ~10-year-old LG, is it reasonable to attempt a T-CON/ribbon/rail diagnosis first, and only then declare “panel not worth it”? If so, what repair-cost threshold would you personally stop at?

I can provide a short video showing “2 seconds OK → vertical bands/lines” and photos of the screen/menus.
Located in Portugal (EU). Thanks for any guidance.

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2 Answers

oldturkey03 @oldturkey03 Rep: 839.5k 1.3k 944 2.4k · Answer 1 · 2026-01-10T19:21:50-07:00

@joaomartin60969 looks like your screen actually changes in the horizontal area after ~8 sec (almost like double vision) This will not be a COF error. It is possible that this is a T-con error but most likely a panel error. Check the components on your driver boards. Those are the long skinny boards where the T-Con ribbon cables connect to.

You can sort of test this by disconnecting your power cord. Then disconnect one of the ribbon cables going to the driver boards from the the T-con board. Connect your power cord and turn your TV on. Now you will only have one half of the screen work. Check to see if you get the anomaly happening on the side that works. Next, test the other side the same way.

Turn your TV off, disconnect the power cable, reconnect the ribbon cable to the driver board, disconnect the other cable. Reconnect the power cable and turn you TV on. Let us know what you get.

The other thing you can always try is to turn your TV on and once it shows that error get some freeze spray and cool down the components on the T-con board. If you can restore your picture temporarily with this, you know you have a bad component on the T-con board.

Just as standard caution, always keep your fingers of the power board since the capacitors will carry your household current and can zap you pretty good. Using common sense makes working on this TV a pretty safe task.:-)

What safe, non-invasive tests would you recommend to separate T-CON vs panel vs power before I spend money? You will have to remove the rear panel for any test. You can't test this without opening the TV.
For a ~10-year-old LG, is it reasonable to attempt a T-CON/ribbon/rail diagnosis first, and only then declare “panel not worth it”? If so, what repair-cost threshold would you personally stop at? That depends on how much the cheapest TV is that has the same features as yours and how much money you want to spend. I will not replace TV panels that large since the cost is more then a new TV would be. That is where I draw my economical line :-)

@jayeff I had to convert your comment to an answer to access the manual. As a comment if would give me a 403 access denied error. Once I converted it, it let me access the manual. Weird.

Anyhow, I thought about this being a main board error as well, but what made me go pass on that, is the double vision as well as the horizontal lines that seemed to pop up on the top of the screen. Those give me some concern that it is an issue with the CKV lines.

You are absolutely right with making sure to check the main board as well. It is most certainly possible to be a fault as well. — oldturkey03