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2021 Samsung Neo QLED Intermittent backlight failure

Out of nowhere, turned TV on and found black screen. There is a dark image on the screen and sound works fine.

After some trial and error, I have found that if I power on the TV and let it sit for 5 minutes or so, unplug it and plug it right back in, TV operates normally, picture is perfect. It will operate like this for hours. I have never left it on to find out how long. I can switch it off and on without issue after it has "warmed up". If I let it sit off for a few hours and power it back on, same black screen until I let it warm up, unplug and plug it back in and it operates fine.

I was planning on starting with the low hanging fruit and replacing the trio of boards and see what happens. Curious if anyone has ideas on what may be the cause here if it isn't a board. Almost seems like I have a bad connection and after it warms up a bit and expands, connections are made and the TV operates normally.

Thanks for any guidance. Added photos of the boards and the before and after photo after the TV warms up for about 10 minutes.

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Model QN65QN85AAFXZA

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Power board issue. Changed it out and TV powers on normally.

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@cmcpolo Awesome!!! Glad you got it fixed!

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@cmcpolo "There is a dark image on the screen" sounds like some of the backlight for the QLED may have issues. The weird thing is that yours are in the reverse as they usually fail :-) check your connectors and check your boards. See if you can find a "cold" solder connection on either the boards, or on the connectors etc. You can identify a bad solder joint by the looks instead of a silvery shine, they are commonly dull in appearance.

It might help if we can see your boards or even your screen when it displays this error. If you can, post some good images of all of that with your Question. that way we can see what you see. Adding images to an existing question

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Thanks. Uploaded the images.

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@cmcpolo Thank you for that. I dislike to be a PITA but could you post one more of the board shown in the 2nd picture? The power board and the mainboard really are not laid out to control just certain segments of the display. That particular board is commonly responsible for row and columns. I wonder if that is where the issue stems from.

:Look slike there is a BN number on one of the labels but it is hard to identify. Can you give us that number?

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Thanks. The BN number for that board is under some tape. It is BN94-17100A. There are two (2) other smaller tags with BN numbers on this board as well in the photo. Added to the original post.

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@cmcpolo I like this already. A subcon board that also drives the LED's. I think this is the one we need to focus on for now. Looks like each one of those side connectors (CN1000,CN1100 and so on) is responsible for a different set of lights. Is there anything on your board that looks like it cold possibly be different then the other ones. Make sure that the ribbon cables on this are all properly seated and do not have any tears or corrosion etc. Sometimes pulling them and then reseating them helps as well.

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Replaced the subcon board. Unfortunately, problem persists. Power board next I think.

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Chad Cooke will be eternally grateful.
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