One vertical green line on my AQUOS LC-70LE740E TV

[hoot]

Hello,

on my AQUOS LC-70LE740E LCD TV there is a vertical green line on the screen. (pictures below)

Does anyone know what the issue could be?





Up close it looks something like this.



Can this fault be serviced?

What I want to do is the following:

gently pressing on the ribbon connections along the top and bottom of the panel in the area of that line. Pushing a driver IC onto the flex cable it sits on to restore the lost connection. When the problematic area is found installing something that pushes it permanently.

Thanks in advance

[hoot]

When I loose the contact on the connection and apply different amounts of pressure I get this kind of artifacting (some of it looks just like the original vertical line. The original vertical line however does not go away when reconnecting):

[hoot]

To be clear...
This is the connector fully engaged:

This is the connector fully loosened

This is one of the many artifacts that apear, when the loosened connector is lightly pressed down (notice the permanent line is brighter):

This is another one of the many artifacts that apear, when the loosened connector is lightly pressed down:


These artefacts are lines or plains that are white, blue, red or green. Next to that connector is another one that behaves the same as far as I can tell.

Another idea would be to replace one of the PCBs:


There is another one on the right of them but its covered by a metal plate. The whole housing is of metal, beautiful construction.

Maybe unplugging the cables on the pcbs and cleaning them would do the job? I have no clue about this stuff, but im feeling like dumpimg this high quality made in japan TV is a waste. Defenitly no warrenty on this one. Pressing the ribbon under the connector doesnt effect the screen at all.

[ivtec]

There is nothing you can do, this is a display fault, I have a Philips 46 with same line but my luck is right in the left side close to the side and only notice if i watch a movie and i fixate my eyes on it, since i use this tv most times for soccer and field is green, not bothering me at all,

[Davi.p]

you can only try to slightly reflow the near COF using stylus soldering iron, some precautions must be taken..

[hoot]

Sorry, I'm not a native english speaker. What does COF stand for?

@ivtec I see. Maybe I could get into golf... If per chance Im able to come up with a solution Ill let you know, so you can enjoy your soccerball games in full glory!

[Davi.p]

COF are the chips soldered on to the tab, therefore the tiny flat cables glued to the screen, if you watch them normally the chips are in the opposite side of tab, so you must carefully heaten the top side under the chip pins, but first: remove/flip the panel's board and put a shim under the right cof so you can make pressure without benting / breaking it, not use plastics or metal, must use some heat resistant and possibly not much heavy. Then remount the pcb, now with a tip scroll under the chip pressing it until you find the point that restores the correct image, so you can heaten with sodering iron, do it gently with increasing duration / pressure.. until the line goes away and stay there. Be very sensitive because the chip is like glass and breaks very easily..

[hoot]

I see! Thank you for that detailed describtion. This seems to require a substancial amount of skill. I will think about it, but I am not sure if I am skilled enough to do this. Shouldnt have the pressure I applied on there have had an impact on the green line on the screen?

Is it possible that a PCB swap could do the trick?

[Davi.p]

You don't understand me, the fault is in cof chip soldering, don't stupidly waste money in boards that would be helpful for another user, i'm about 13year behind lcd repairs, i know what i say.. if the heating doesn't improve, the fault is in cof line output circuitry..

[hoot]

Originally Posted by Davi.p

You don't understand me, the fault is in cof chip soldering, don't stupidly waste money in boards that would be helpful for another user, i'm about 13year behind lcd repairs, i know what i say.. if the heating doesn't improve, the fault is in cof line output circuitry..

That is good to know, thank you. I'm lucky to benifit from your experience. So I will need to fix the soldering of the COF chip. I'm worried about going near that area with a soldering Iron, but since you have so much experience I will approach this subject.

I will read your description very carfully and will write more soon.

I will respond tomorrow. Thank you very much.

[Davi.p]

feel free to ask if you have doubts, those films are high temperature resistant plastic films, so you can insist some seconds with the iron on.. to locate the faulty soldering point before using the iron, use a toothpick. If you manage to cancel the line, before closing all up add a soft shim in front of the cof chip to be able to keep it slightly pressed to the frame.

[CityZen]

For reference, here is a set of COF (chip-on-flex) on the tabs of a Samsung TV. Note the long and thin driver IC's. "Tab" refers to tape-automated bonding, and it's the method used to attach the chip to the flex tape, though the name is also applied to the whole COF/tape assembly as well.

[hoot]

Thank you very much, this is critical information.

So Im going to loosen the PCB put epoxy under the COF and put the pcb back to its place.


Then Im going to apply pressure with a toothpick on differrent spots on the area shown below.



After I have located the critical spot Im going to take a soldering iron and apply heat until the line disapears. What temperature do I set my soldering iron at?

[Davi.p]

Ok it's all correct except for epoxy that i don't know its property but i don't have a good material to suggest, i think is ok, for the temperature keep it low like a 20w iron, sorry i've never had a soldering station... empty pockets here..

[hoot]

Very well. Im going to try to locate the spot by appling pressure. Then Im going to apply something between 270 and 370°c for around 0.5-2 seconds on that located spot. Wish me luck.

[hoot]

Appling pressure to the COF next to the green line did not work.

[Davi.p]

Sorry, so decide whether to apply heat or not and keep the screen faulty.
Are u sure is the right tab or is the next one?

[hoot]

Might be the next one. I will double check on both. If it is still worth a shot appling heat although pressure did not show any change I think I'll do it anyway.

[Davi.p]

COF contacts are in the perimeter, but not all the lines to the screen start from the side that face to the screen

[hoot]

Okay, I will focus on the COF closest to the green line and the one next to it.