2 LG 86UN8570AUD Horizontal Lines, is T-Con likely?
I have an 86" LG LCD TV that is less than 5 years old that has started displaying horizonal lines and freezing most of the screen every 2-3 seconds.
In an effort to get part number and try some simple diagnostics I took the back off and reset all the cables which had no effect, I then disconnected the mainboard and when powered on I get a rotating color pattern and I can see the lines across the top part of the screen, most lines are not constant but follow a patteern with the screen freezes and unfreezes. I then disconnected 2 of the cables from 1 side of the T-Con board and when powered it shows all white on one half of the screen and black on the other and no horizontal lines. When I switch to the other 2 cables on the T-Con board I only get a little bit of the top of the other side of the screen in white with lines and then it goes white across the whole screen with some horizontal lines and then one side fades to black.
I will attach a video, just trying to determine if it is likely a t-con board issue or something with the panel.
Pictures:
Thanks,
Don B.
crwdns2934109:0crwdne2934109:0
@grumpygeek going by your description and your video, this looks like an issue with the left side (Right hand see when you look a the screen) driver boards. those long skinny boards where the T-con board connects to. Now with a screen that size, I would think there are more then 0ne board per side. Those boards should have interconnect ribbon cables. Separate those (one at a time) and repeat the test where you disconnect the T-con ribbon cables to each side. Let us know what you find out. 86" that's a beast to work on :-)
crwdns2934271:0crwdnd2934271:0 oldturkey03 crwdne2934271:0
@oldturkey03 Just 1 board with 4 connections in 2 groups, would that be different quadrants? The cables are only long enough to reach the connections. I might be able swap the cables in the groups, just wasn't sure they were the same... they do look the same. I will add a picture to the main post. And your right it is a beast, the back cover was much heavier than I expected.
crwdns2934271:0crwdnd2934271:0 Donald Bailey crwdne2934271:0
@grumpygeek let's see what you are looking at on the driver boards. I would not like to have you swap a cable just to melt anything on the driver board ;-) Okay I see what they did. instead of running ribbon cables between the boards they use separate cables from the T-con board. Any chance you can get close enough to those boards. What happens if you disconnect one ribbon cable from the T-con board. What does your panel show compared to two?
crwdns2934271:0crwdnd2934271:0 oldturkey03 crwdne2934271:0
@grumpygeek in your video, check around the 30 sec. mark, see how it does from right to left? You will most likely have to slow your video down. That is a common way for your display to act with a bad driver board. The actual issue here are the Gate Drivers that are (very simplified) responsible for the horizontal picture. Sometimes those can be bypassed by disabling them. I spare you the whole talk on the CKV lines and blah, blah, blah but I am thinking that a Tape-Off might make it work. Just need to research "the beast" a bit more :-)
crwdns2934271:0crwdnd2934271:0 oldturkey03 crwdne2934271:0
@oldturkey03 I can get a T-Con board for $20-30, might give it a shot, but I don't think I will go futher than board swaps. Wife really wants a new TV (was looking at TCL QM7K 85") I would just assume save $2000 or at least keep it out of the landfill. My 15-20 year old sharp LCD keeps on ticking and still looks pretty good. Thanks for the help.
crwdns2934271:0crwdnd2934271:0 Donald Bailey crwdne2934271:0
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