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Old 05-30-2020, 04:09 PM   #1
Ifixstuff9
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Default LG 49UF6400 tint on half of screen + no OSD?

Hi all,
I have a LG 49UF6400 with two issues. The first is a colored tint on the left side of the screen. The color of the tint depends, but I've seen red, green, and purple so far. I can see a normal image behind the tint as shown in the photos. The tinted side flashes rapidly between "normal" and "tinted"

I suspected either the panel or the TCON, so I tested the TV with one of the panel cables disconnected. With the left side unplugged, the left half of the screen is white and the right is black. With the right unplugged, the left has vertical bars and the right is white. I have attached photos.

At this point I felt sure that at was either the panel or the TCON, but there is another issue as well... I can't get the TV to generate ANY on screen display. At no point when testing the TV did it display and content of its own, such as a "no signal" message, the LG logo on startup, the settings menu, the built in apps, etc. If I power it on with no video source I only get a black screen (with the tint mentioned earlier) until I hook it up to a video source, at which point it will display only that.

At first I thought the TV was completely unresponsive but that isn't true. This TV has a frame dimming feature, and I've noticed that if I display a black image on my video source (which causes the backlit to dim) and then press, for example, the menu button, the backlit will ramp up while the invisible menu is open and dim again when I press exit. So it seems like the TV is generating a menu and adjusting the backlit accordingly, but it won't display it.

I've never seen or heard of the second issue before. What do you guys think? If the TV can't display an OSD in addition to the tint, does that imply that both the mainboard and TCON/panel failed, or could all these issues be caused by the mainboard itself?
Attached Images
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File Type: jpg re3.jpg (602.0 KB, 22 views)
File Type: jpg re4.jpg (601.2 KB, 18 views)
File Type: jpg re5.jpg (601.1 KB, 13 views)
File Type: jpg re6.jpg (498.1 KB, 16 views)
File Type: jpg re7.jpg (587.1 KB, 13 views)
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Old 05-30-2020, 04:48 PM   #2
nomoresonys
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Default Re: LG 49UF6400 tint on half of screen + no OSD?

Tcon there for 25 bucks, might be the problem, there's also one for 18 or 19 but it's on a slow boat from china: https://www.ebay.com/itm/LG-6871L-42...AAAOSwDQxezqJ5
__________________
1) https://www.youtube.com/watch?v=4F2J1Dkf4Is
HIGH VOLTAGE HAZARD demonstration. Video by Electronic Doberman.
2) https://www.youtube.com/watch?v=4v8DcqCNG4A
Power supply board voltage testing by shopjimmy.
BE VERY CAREFUL WITH POWERSUPPLY, VOLTAGE ON PRIMARY/HOT SIDE CAN BE DEADLY, THE CAPACITORS CAN HOLD A VERY BIG CHARGE LONG
AFTER TV HAS BEEN UNPLUGGED.
3) Test connector from mainboard to powerboard on powerboard side with all boards hooked up, test with tv plugged in but off then hit power, report both conditions here, give pin number, pin description/name and condition both off and when you hit power on. So we can see all the voltages and what they are doing.
Donations accepted with a smile and a Thank you
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Old 05-31-2020, 12:59 PM   #3
Ifixstuff9
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Default Re: LG 49UF6400 tint on half of screen + no OSD?

I added the TCON to my watch list, but I don't want to spend money on this TV just yet because I still haven't figured out why it won't display an OSD. Surely the TCON has nothing to do with it, right?

I also noticed that the two chips I circled in the picture got VERY hot even though the TV had been running for less than 30 minutes. Seems strange that they would generate that much heat in so little time, especially considering that the TV wasn't running built in apps or doing anything "demanding"
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Old 05-31-2020, 01:17 PM   #4
diif
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Default Re: LG 49UF6400 tint on half of screen + no OSD?

That's a BGA issue on the mainboard not a tcon issue.
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Old 05-31-2020, 08:28 PM   #5
Ifixstuff9
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Default Re: LG 49UF6400 tint on half of screen + no OSD?

Hmm, any idea where I can find a reasonably priced mainboard for this TV? Only one I could find on eBay was $175, and it seems to be out of stock everywhere else.
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Old 05-31-2020, 09:24 PM   #6
neilc6
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Default Re: LG 49UF6400 tint on half of screen + no OSD?

I have used this seller before for main board repair with no issues. Not sure if it will correct your problems so you can contact him first.

https://ebay.us/h6udhv
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Old 06-03-2020, 10:55 AM   #7
Ifixstuff9
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Default Re: LG 49UF6400 tint on half of screen + no OSD?

Thanks for the suggestion, I contacted him and he thinks he can fix it. I'll post an update when I get the board back
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Old 06-16-2020, 10:30 PM   #8
Ifixstuff9
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Default Re: LG 49UF6400 tint on half of screen + no OSD?

Final update, I installed the repaired main board and TV works fine now
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