LG 42LG5010 LCD picture issue

[notallbad]

The left half of the screen is darkened and the very far left side has a delay in the picture refresh, retains image almost like slow motion with moving objects and with subtitles the text remains after it changes.

The image has the same fault on all source inputs, Hdmi, DVB, Scart.

I am dreading the thought of it being a tab bond issue but believe that is the fault, would prefer more expertise knowledge to confirm before proceeding further. It does occur to me that it could be the T-Con due to the slow refresh rate though.

The first image shows the darkened area and the second photo is showing the effect of switching from blue screen to black screen in the Service settings, ignore the text my hand was not very steady holding the camera so a bit blurred etc.. but pay attention to the blue area still visible, it takes a while to completely change to black.



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[tom66]

Re: LG 42LG5010 LCD picture issue

Definitely looks like a tab bond fault to me, has all of the characteristics, it's getting so common nowadays.

[notallbad]

Re: LG 42LG5010 LCD picture issue

Thanks Tom

[cashkennedy]

Re: LG 42LG5010 LCD picture issue

I agree its most likely tab bonding, but try pressing the rim / or disassembling it and pressing all the tabs. If you find one that is clearly bad, (and the tv works when pressing 1 place ) then you can use a ruber spacer / foam to hold it in place get some more use out of the set.

[tibimakai]

Re: LG 42LG5010 LCD picture issue

I would rather use Bud's suggestion and use that heat transfer material, which are used on top of ICs, to transfer heat to a metal cover, like the ones at the T-con board.

[cashkennedy]

Re: LG 42LG5010 LCD picture issue

Yeah if you can get your hands on non conductive heat transfer pads, those would be the best fix if you have a set that responds to pressure on the tab.

[budm]

Re: LG 42LG5010 LCD picture issue

I got mine from Digikey, it has sticky one one side which help keeping them in place when you put the frame back on. fold it 90 degree so it make contact with the tab and the IC on the flex board.
https://www.badcaps.net/forum/showth...LN52A530P1FXZA

[notallbad]

Re: LG 42LG5010 LCD picture issue

Thanks for the replies, it was indeed a tab bond fault! Hence why I haven't responded sooner, been busy disassembling and re-assembling til I got it right.

Bench testing at the moment to see how long it lasts, shall report back when I am convinced either way.

Thanks again.

[tom66]

Re: LG 42LG5010 LCD picture issue

Out of interest what LCD panel was inside it? ChiMei, AUO, LG Display, Samsung, Sharp? Those five I know for sure have tab bond problems, so common. Strange there was no recall on them, like what happened with the Samsung bad caps scandal.

[cashkennedy]

Re: LG 42LG5010 LCD picture issue

I was under impression the early Samsung 46 / 52 failures (that also affected sony) were all Samsung panels, and those are usually the easy ones to fix with pressure. Although it seems like probably 50% have failed at this point 5 years later, there wasn't a huge sudden fail rate at 2 years like with the caps , so I think it kinda prevented it from getting as much attention.

There was also a bunch of 15" monitors back 10 years ago that the tab would come completely off.

And I think the 32" / 40" sonys are chimei or something and might be something more complex then simply coming loose, like perhaps the antistropic adhesive was put on slightly wrong / or the tabs weren't aligned well. (this seems like a very small group of bad panels compared to the other 2 groups above)

It is interesting though that's its really flaring up lately, seeing people constantly with tab bond issues around here now.

[tom66]

Re: LG 42LG5010 LCD picture issue

LG Display (formerly LG.Philips) had some early problems with tab bonds on their 37" panels only, quite rare, but there weren't many issues, minor in comparison to the others. It was only around the time when they were actually called LG.Philips, but Philips bailed. (Poor decision: LG Display is one of the largest OEM suppliers now. Their position was weak a few years back, but it's only got stronger and they are steadily eatng away at Samsung's market share.)

Samsung were definitely the first ones to have it on in such severity on both their 46" and 52", then later some 40", all 1080p.

Then AUO started seeing problems (half/full screen scrambled/missing) on at least their 42" and 46" 1080p panels.

ChiMei have problems with 26" 720p panel tab bonds and with a friend I have fixed two of them. Not sure when these began.

Sharp have had a few minor issues with them, affecting mostly their smaller 19~32" 720p panels which are manufactured in partnership with Samsung and ChiMei (perhaps shared technology here causing the issue. Sharp invented the LCD TV, and the modern large screen LCD, over 25 years ago, so they should know what they are doing with tab bonds.)

Industry wide problem, and little or nothing has happened as a result.

My theory is it is do to with the switch to lead free solder and the changes in the driver ICs to push higher density/higher speeds out of these chips (120Hz etc.) making them run a lot hotter and thus putting more stress on the bond.

Interestingly the failures between panel manufacturers are almost always consistent, suggesting common faults:

LG Display loses vertical sync and becomes darker on the left or right edge (VCOM, TFT ON/OFF voltage loss perhaps, or VSYNC signal loss.)
Samsung loses vertical sync, browish tint, and gets motion blur on the left edge (VCOM, TFT ON/OFF, etc.)
AUO loses vertical sync/video clock ONLY, and can affect either side but left hand edge is more common.
ChiMei loses whole picture when tab bonds go bad. Sometimes faint image visible but that's all. Maybe loss of AVDD.
Sharp loses vertical sync with whole image affected, vertical bars blurring etc. Probably loss of some important clock or control signal

so whatever is failing, it is in the same place on each tab bond every time. Hmm...

[notallbad]

Re: LG 42LG5010 LCD picture issue

Just for info it is an AUO panel on this TV.

[tom66]

Re: LG 42LG5010 LCD picture issue

Ah, so if AUO panel, then AUO can also suffer from browning and blurring failure, which is a lot more similar to Samsung. So AUO have more than one mode of tab bond failure suggesting multiple weaknesses.

[notallbad]

Re: LG 42LG5010 LCD picture issue

So after sometime of testing the fault re-occurred so have decided not to bother with it again.
Mainly as I would not feel comfortable selling this TV with a fault that without a doubt will just come back most likely within a months use.
Don't get me wrong, I am sure some fixes will last, just not mine!

Its unfortunate as the panel is in pristine condition, oh well!

[tom66]

Re: LG 42LG5010 LCD picture issue

I've only had one like that which was intermittent, if done right tab bond repairs would appear permanent.

[notallbad]

Re: LG 42LG5010 LCD picture issue

Yeah, I think this must be an odd ball one.

Well at least I am now familiar with typical faults caused by it, it did give a number of peculiar display symptoms, now I see how they can be easily mistaken for T-Con b/d issues.

[highpulse]

Re: LG 42LG5010 LCD picture issue

I there , sorry the ignorance , my main área is laptops and videoconsoles .. ^Tv's i know a bit but not much as you guys , i've the same issue on the same TV , but now im asking to myself what is the tap bond you guys mean ? , is does lockers on the Tcon board the one were the ribbon cables connect ? . all the help is very welcome .

sincerely

Jonathan

[tom66]

Re: LG 42LG5010 LCD picture issue

There are some flex boards running along the length of the panel. The tab bonds are the connection between the flex board and LCD panel.

[highpulse]

Re: LG 42LG5010 LCD picture issue

yes exactly what i was thinking . thk guys , let see if it solves the problema

[highpulse]

Re: LG 42LG5010 LCD picture issue

Btw i find only 2 ribbon that come from the screen , both on the top and they connect to the Tcon board . the outher 2 ribbon i notice , are the ones that connect to each board of the inverter(way of syncronization of both maybe)