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

[ivtec]

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

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

If you have the green line in the meddle or close you have nothing to loose, if it was my Tv had it in the meddle that would bother me and i would have nothing to loose i would try Davi.p instructions if i couldn't get rid of it i would trash tv anyway. Some people don't mind the line, i do,i hate it if they are very noticeable , it's a state of mind thing

[hoot]

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


I will apply heat (270-370°c) for 1-2s on the "1st" COF. If it does not work I will move on to the "2nd".

On each I will start in the middle and move outwards.

[CityZen]

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

I'm not an experienced TV fixer, but based on my understanding of LCDs, the problem could be in a couple different places: the connection of the driver chip to the flex cable, or the connection of the flex cable to the actual LCD. If probing around the chip yields nothing, consider gentle probing where the flex meets the screen.

[hoot]

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

That I will keep in mind. Do you suggest going with the soldering iron where the flex meets the screen?

[CityZen]

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

I don't know, but I wouldn't do it myself. Just try probing with a wooden or plastic probe first to see if there's any effect.

[hoot]

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

Got ya! First I'm preparing for the heating operation. If the TV survives without the issue being resolved, I will do that. Actually I could apply pressure to these points before I do that.

[CityZen]

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

I just had a thought about an experiment that might help us both.

LCD screens have drivers for the horizontal lines (rows) and for the vertical lines (columns). Normally, the drivers for the horizontal lines are on the sides of the screen, and are attached similarly to how you see the tabs on the bottom of your screen.

However, on recent LCD screens, I've only seen tabs on the bottom. I've had a theory that the drivers for the sides are also fed through the tabs on the bottom of the screen. If this is the case, then the next question is which tabs feed the rows, and which ones feed the columns? I suppose it's possible that a tab could feed both rows and columns, as well.

In any case, the experiment is simple: run the TV with one of the outermost tab boards disconnected. (Unplug the U-shaped flex cable that joins two tabs.) Then observe the effect on the image. (There's a small possibility that running the TV like this could result in bad things, but I think it's not very likely. You must decide if you're willing to take this risk.)

I'm currently trying to resolve an issue on a TV of my own, though right now it's in a different place than I am, or I'd try this experiment myself.

How might this experiment benefit you? Well, if it is the case that the outermost tab is responsible for the horizontal lines, then it must be the case that the tabs that feed the vertical lines are just the ones from the center boards, and therefore the ones you need to check are different than the ones you marked. (You marked the 3rd & 4th tabs from the left; you might need to check the 5th or 6th.)

[Davi.p]

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

Citizen the experiment you are suggesting is totally unuseful, 4 your information rows are driven by chips within the glass.

[hoot]

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

According to what I have researched the POC ribbon can take 230°c long time exposure and 400°c short time exposure. So the heat will most likey be an issue for the surrounding components before it damages the ribbon itself. I will get some ribbons from an old and broken monitor so I can practice a bit.

[CityZen]

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

Citizen the experiment you are suggesting is totally unuseful, 4 your information rows are driven by chips within the glass.

I can understand that, but one thing is still needed: how does the data get to the drivers within the glass? The only connections are at the bottom of the screen.

[Davi.p]

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

the question you make is not relevant, the defect is on a column connection of source driver, gate drivers deesn't matters here..

[hoot]

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


Ready for practice!

[CityZen]

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

the question you make is not relevant, the defect is on a column connection of source driver, gate drivers deesn't matters here..

The question I asked is certainly relevant to me.

The relevance to the original poster is as I stated: it could affect which tab corresponds to the line in question.

[CityZen]

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

Okay, so I got back to my own TV and tried the experiment I mentioned earlier (leaving one bottom board disconnected). Unfortunately, the result was not as interesting as I hoped: the whole screen fails to show any image.

I did try various experiments masking out some of the connections, and they did make certain vertical bands of the screen display improperly.

After thinking about the way LCD screens are driven, I realized that the horizontal rows are only driven by timing signals, whereas the vertical columns are driven by pixel data. Only two signals are needed for the rows: reset and count.

For this thread, the only conclusion is that the tabs hoot indicated are probably the ones he needs to check.

[hoot]

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

That's good to hear. I was just guessing.

[hoot]

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

Since I wasnt able to find my modern soldering station I have used this old timey heavy duty one:



Here I have three ribbons. The one at the bottom I have played around with quite a bit to get the feel for it. The middle I have applied 1-2s light touch in the middle as well as 2 points to the left and 2 points to the right. The top one is untouched. The deformation of the flex is due to me taping them onto epoxy:



Here I did apply 20s in the middle:



Here another 20s on the some COF:



Superficially they seem to be quite resilient. When I'll do this on the TV I will stick to 1-2s and a light touch. I will have a metronome running at 240bpm to ensure the timing is right.

[Davi.p]

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

how many watts that iron?

[hoot]

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




Thats all it says. Judging by what your saying the iron did not get hot enough?

[hoot]

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

I now have tried with this one (no station directly into the powersocket) for 20s in the middel (5min heatup time):

[hoot]

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



Started with 230°C 1-2s on different points of the COF on the left and right flex next to the green line, went to 260°C, to 300°C, eventually to 370°C. The TV survived just fine the line however remained.

By playing around with the connection seen below, I can get a hole in the line. Disconnecting completly will turn the whole section white. Dont know if that is a useful clue. If there is nothing more to be done I will get rid of the TV.