Why is this TV's one side darker except for some horizontal zones?

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LG Television

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kentymail @kentymail

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Posted: May 17, 2021

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Why is this TV's one side darker except for some horizontal zones?

TV model: LG 70UM7370PUA

This TV has its right side darker than the left, except for certain horizontal areas where it seems to match the left side in brightness. Additionally, the darker areas on the right side areas seem to refresh slower; when the image abruptly changes, it takes a while before the new image reaches the far right end of the panel, if that makes any sense. Also, it seems there’s some wavelike distortion within the panel itself on the right side, although it’s not too noticeable unless it’s a solid bright color.

I’ve only seen others online whose TVs have horizontal line issues, or whose TVs have one side darker than the other, but none whose TVs seem to match this TVs image condition.

Is there a basic reason why this is happening?

Typical image:

Displaying a white background (with some text):

With one t-con ribbon disconnected:

With other t-con ribbon disconnected (receiving the same image input as above):

Answer this question I have this problem too

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2 Answers

Ben Heinisch @armorben Rep: 1.2k Armor Techs Inc 6 3 1 · Answer 1 · 2021-05-26T12:28:30-07:00

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Ben Heinisch @armorben

Rep: 1.2k

Armor Techs Inc

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Posted: May 26, 2021

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Something is wrong with the backlight. Main things that fail are be the inverter or the leds. Typically when I see an inverter fail, all the leds go out, so first thing I would do is try putting some new leds in. You should know that this typically involves removing the panel from the front of the TV, when doing this be very careful not to catch the ribbon cables running off of the panel on something as this will cause lines running across the screen.

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Thanks for the advice!

I wonder if it's a backlight issue myself. Would a backlight problem cause such a sharp difference in brightness between adjacent regions on the display as shown in the photos? I assumed backlight issues would mostly cause areas of gradual, dimmer lighting, but not such a dramatic shift as what I notice here.

Also, I've uploaded a few more images (1 showing a white image, 2 with a t-con ribbon disconnected) in case it helps.

May 26, 2021 by kentymail

@kentymail Yes, you can get sharp differences with backlight issues. Typically backlights are set up with several strips of LEDs running either across the length of the TV or from top to bottom. If one strip fails, a column (or row depending on placement) of the panel will be dimmer than the rest. How big that zone is depends on a couple different design choices.

Looking at those other images, it does make me question if the backlight is the only issue here. Almost reminds me of some TVs I saw that sat outdoors and had some water leech around the panel. Now that I have seen it in more detail, a backlight swap may help, but there could be another issue here, maybe with the panel or t-con board. Definitely a unique issue.

May 27, 2021 by Ben Heinisch

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