LG 55sk8000 plb ..snow in the middle of screen but can see that picture exists there

[burbutsalos]

Hello everyone.

I have this TV set which has this issue. It shows a vertical bar im the middle of the screen.
The panel has 12 cofs and the problem seems to be on the territory of the first cof on the right side.
The tv fires up and you can see a good picture exept that vertical part where multicoloured pixels exist.
The strange thing there is that you can see behind that snow that it shows picture but as if there are these pixels in front so you cannot see clearly.

The effect is there even on a completely black screen.

The screen does not change if a press slightly the cof.

no shorts on capacitors there after a quick test

Any suggestions on what to look?

[nomoresonys]

Re: LG 55sk8000 plb ..snow in the middle of screen but can see that picture exists th

If your bonding of the panel to the driver boards all look ok, I think I would try a tcon replacement.

[KYBOSH]

Re: LG 55sk8000 plb ..snow in the middle of screen but can see that picture exists th

The chip itself could be bad right?

[nomoresonys]

Re: LG 55sk8000 plb ..snow in the middle of screen but can see that picture exists th

Maybe, it looks like there's a couple areas, If that middle line is right on one of the cofs, feel if that cof is hotter than the rest, also many times you will see the cof is darker/burnt looking/distorted/might be a little hole nearby, look for a clue like that.

[burbutsalos]

Re: LG 55sk8000 plb ..snow in the middle of screen but can see that picture exists th

thanks for the replies guys.
This model has no separate t-con. only mainboard.
All cofs from both sides are hot but not so much that i cannot touch them for a while.
As far as i am able to see the cof it seems clear .
I have not tried to dismandle the panel to see the cof from the panel side if it has any burns or black spots.
You think i should check that also?
@KYBOSH you mean the actual chip on film is gone bad?

[nomoresonys]

Re: LG 55sk8000 plb ..snow in the middle of screen but can see that picture exists th

I'm trying to remember if there's a easier way to test them but I'm drawing a blank.

[nomoresonys]

Re: LG 55sk8000 plb ..snow in the middle of screen but can see that picture exists th

Ok, does this tv have cofs on the sides? Sometimes they are pretty small and don't have boards attached.

[nomoresonys]

Re: LG 55sk8000 plb ..snow in the middle of screen but can see that picture exists th

There's a technique that I have seen many times on youtube, involving running a strand of wire from cof to panel driver board.

[nomoresonys]

Re: LG 55sk8000 plb ..snow in the middle of screen but can see that picture exists th

Not sure if this is your problem tho but here it is: https://www.youtube.com/watch?v=HNsI8Lx0ro4

[burbutsalos]

Re: LG 55sk8000 plb ..snow in the middle of screen but can see that picture exists th

Thanks for the info nomoresonys !!!
As far as i know after checking the panel model it does not seem to have any side cof's .
It seems to be with chip on glass at the sides
I watched the video very tricky job to do !!
But i see that the Tv there has problem all over the panel and the lines are smooth and not like the old time no signal snow
This is what is very strange here, I tried searching for pictutres over the internet with same issue as mine and i see none..
Also the most weird of all is that <<behind>> the snow you can see the pixels changing according to the shapes displayed on tv that time ..

[nomoresonys]

Re: LG 55sk8000 plb ..snow in the middle of screen but can see that picture exists th

Indeed it's a strange kind of bar that I haven't seen before.

[burbutsalos]

Re: LG 55sk8000 plb ..snow in the middle of screen but can see that picture exists th

Please help guys .... Has anyone ever seen such an issue? I have been searching for days now and nothing comes up. Its like that cof is working but ..with noise....

[burbutsalos]

Re: LG 55sk8000 plb ..snow in the middle of screen but can see that picture exists th

I did some tests .I know that the last one is not a correct one but i did it .
I fired up the TV got the expected picture.

I removed the right side ribbon , the one with the problem , and i got a correct half picture from the left.

I remove the left ribbon and i get a half white half black screen .
The white part is on the left side and gradually darkens and the right side stay black even the part that has the snow when working with both ribbons.

And finally i fired up the tv with both ribbons got the picture with the issue and then .. i removed the left side ribbon to see what happens. i got the pictured attached... Shouldn't, i still have the snow on the problematic part of creen????
I tried to get voltage ratings from testpoints and this is what i got

Left side (ok)
CLK1 to CLK8 : 2,37V
VGH :16,5V
VGL1 : - 6,95 V
VGL2 : -14,85 V
VCC : 3.3v

Right side (snow on one COF)
CLK1 to CLK8 : 2.36 V
VGH : 0 V
VGL1 : -14.65
VGL 2 : -14v to 0 V
Vcom : 5,2 V

I am at a loss here..

[burbutsalos]

Re: LG 55sk8000 plb ..snow in the middle of screen but can see that picture exists th

Hi everyone... any ideas about the issue in the screen ? I am lost and domt know what to check. Any help will be appreciated

[Storyteller12]

Re: LG 55sk8000 plb ..snow in the middle of screen but can see that picture exists th

It’s either bad maonboard or bad panel. I have seen a few LG TVs that have similar issue with snowy pic and it’s the mainboard processor that’s failed. You can try a reflow and see if it makes a difference. Most likely it’s a panel issue though