Sony LD-65X850-8c vertical lines on display problem

[nomoresonys]

Re: Sony LD-65X850-8c vertical lines on display problem

The peel off one side is maybe an option, usually when it works, the tv has a good picture on the half screen with all good drivers, unhooking the tcon ribbon cables to panel one at a time and seeing if you get half a good screen, it's usually the outside ribbon cable. The peel off method is for tvs with tabs on the sides.

[clabr]

Re: Sony LD-65X850-8c vertical lines on display problem

The peel off one side is maybe an option, usually when it works, the tv has a good picture on the half screen with all good drivers, unhooking the tcon ribbon cables to panel one at a time and seeing if you get half a good screen, it's usually the outside ribbon cable. The peel off method is for tvs with tabs on the sides.

I know about the COF peal of method, and about the tape cut out method which I didn't find it feasible in my case, but that is probably because I didn't know enough about it.

I really wanted to go with the method of cutting the lines that go from the buffer PCB boards to the left side gate drivers, if just somebody had pointed me out which exactly do I need to cut for this particular AUO chip TV.

As I've said the problem seemed to be and indeed was one of the COFs on the left side that was in short. It didn't let the Tcon function properly.

I peeled off all the left side COFs eventually and it solved the no good picture from the start (all those vertical lines).

I will post more details.

[nomoresonys]

Re: Sony LD-65X850-8c vertical lines on display problem

No need, Freakafter8 enlightened us of this nifty fix 4 years ago, his tv saving thread has nearly 1000 posts,
THANKS Freak.

[clabr]

Re: Sony LD-65X850-8c vertical lines on display problem

No need, Freakafter8 enlightened us of this nifty fix 4 years ago, his tv saving thread has nearly 1000 posts,
THANKS Freak.

Yes I know, many have done it with success.
I meant to post some of my findings changes of the display after removing one side of the COFs (brightness sharpness loss etc)
There is also a problem, a not so thin horizontal line left in the display that was before and is now aswell (i guess 4,5 real LCD lines) that I hope I could get rid of.
and maybe gain more info about the role of double sided gate drivers (how are they used)

[clabr]

Re: Sony LD-65X850-8c vertical lines on display problem

As I said, I finally decided to remove the problem COF (and all the side COFs afterward)

The display has a problem still:
A horizontal line (a pretty thin line from normal viewing distance (I guess 4,5 real liquid crystal lines in reality; 4k Tv))

It is from edge to edge (in the sense it doesn't fade away at all).
It changes colors interestingly:
it gets it colors somehow from the adjacent lines
it has different colors from edge to edge (not just one solid color from 1st column to last)
also it seems slower (changes colors slower)
it goes to black only when the picture is all black

Is there anything I could do to make it go away?
From what I've described I guess I could conclude it is not a short in the glass, transistor lines from the LCD.

I pressed the COF that is responable for those lines (there are 10 on the side) but there was no change at all.
And I know if a COF has connection problems to the glass because (as you could see in the 3rd attached image) I, unfortunately, had (because of handling I guess) some problems at one of the COFs, which I had resolved easily with a little bit of scotch tape

So, I don't think it is related to the side COF, because this line was from the beginning (you could see the pictures in my original post) even when I disconnected the left and the right side of TCON ribbons.
This is what gives me hope.

Maybe someone with experience has seen this kind of lines and would give me some insight into this problem
Thanks.

[budwich]

Re: Sony LD-65X850-8c vertical lines on display problem

check to ensure that the tabs that you removed were "clean" and nothing was left behind that could "contaminate" the panel tracks. Its possible that the original problem tab on that side "loaded down" the opposite enough to cause a problem on it that unfortunately can't be addressed any further.

[clabr]

Re: Sony LD-65X850-8c vertical lines on display problem

check to ensure that the tabs that you removed were "clean" and nothing was left behind that could "contaminate" the panel tracks. Its possible that the original problem tab on that side "loaded down" the opposite enough to cause a problem on it that unfortunately can't be addressed any further.

Yes budwich, seems like a good explanation, one that I briefly taught of aswell.
Mainly because I have observed (I didn't mention it yet) that the opposite side COF (to the one in short) is a bit hotter than the others (40-50gr; all others are cool 20-30gr).

But how do you explain then, that this horizontal line was present all the time, even when I disconnected the the left and the right "U" ribbons from the source PCBs?
1st attachment - left side COFs active - line is there
2nd attachment - right side COFs active - line is present
(these are older picture I had taken more than a month ago)

That's why I said I still have hope.
How could this be side COF related, then? (when with active right side COFs line is there, with left side active it was there too)

And as you could see there was a 2nd thinner line that was also present most of the time. That one even disappeared before I have attempted to remove the COF.
And there aren't COF connection to glass related problem because I have pressed those COFs thoroughly (and as I said in my previous post, one COF had glass connection problems and managed to press it to function properly (that one that caused an half inch band))

Regarding the cleaning part, indeed I just peeled them off manually with my fingers (using nothing else).
I didn't check if it was a uniform cut at the base.
I didn't clean anything.

[budwich]

Re: Sony LD-65X850-8c vertical lines on display problem

The lines / connections at the panel where the tabs are bonded are fine / small. Any contamination could cause a "slight short" (ie. not a total short but enough conduction that it changes the impedance such it changes the electrical response of the signal).

Not sure you understand the "tabbing" (maybe I don't either).... but the panel is driven by both sides in an "alternate fashion". Your statement "How could this be side COF related, then? (when with active right side COFs line is there, with left side active it was there too)" seems to imply that only the "cof" (what are you actually referring to with this ... post a picture) is the only thing involved. This is somewhat true but the actual physical connection at the panel is also involved in the "signal response" and resulting line display. There was a thread in the past that one person found that adding some "conductive tape" back to the area of the removed tab helped removing left over "display issues" ... in that case, iirc, dealing with slight darkness associated with side that was removed.

It is likely, in your case, that the remaining driver or panel area is still damaged... as you indicated perhaps in the panel / lcd layer itself. :-( There have been a number of posts of "less than complete line removal" with the tab removal operation so it is not surprising again depending on what the ultimate failure is.

[clabr]

Re: Sony LD-65X850-8c vertical lines on display problem

I obviously don't/didn't know much about the internals of the gate driver chips. Today I took some time to learn about their composition (shift register, level shifter, buffer).

I assumed if one is in short, the gate driver is broken and that is it (it will not function at all). And It will not control the opening of any of the 216 lines connected to the chip (this is a 4k, 10 side cof, thus 2160/10 lines).

I didn't think that the gate driver could still function if there is a short on some of its lines.
The more lines it has in short the higher the energy consumption and is impossible for the T-con to function properly

Here (http://lcd-television-repair.com/new...Be_Repair.html )
I can see how a TV with just one side COFs is functioning if enough cooling is applied to the COF with the problems.
Thus, when there is not too big consumption there is a good picture
And you could see those black lines, that band (the lines, the part in the gate drivers that malfunctions, and is in a short state)

But still, here in particular, with this TV I had for repair, the lines are changing colors even though slower somehow.
so I still have hope it's not a short in the opposite COF determined by the COF that had the initial short (and I have removed)
and that it could be some short in the outside connections left by the other chip that malfunctioned, or something like this.
I hope I understood correctly.
I will take a look and clean as much as possible. I don't know yet how much of the connections to the TFTs could be seen though.

[budwich]

Re: Sony LD-65X850-8c vertical lines on display problem

the fact that the one of the remain tabs associated with the area of the lines is warmer than the remaining others is not a good sign. In terms of your "cooling statement" (ie. adequate cooling there after), I am not sure how critical it is but it certainly depends on what the underlying problem was / is.

My first hand experience on a 70 in sharp indicated that the troubled tabs / cof's were hot enough to melt the outer frame at the panel area. Once they were removed, the set was "happy" and has been in service (the same service operational time as before the problem) ever since (3-4 years). There probably are currently "thousands" of these types of saves probably "floating" out there as numbers of posters have carried out the operation. Occasionally, some have issues (lines) after removal. Some have been lucky and looked / cleaned the areas near the tabs that were removed. But if there is a deeper problem (ie. opposite tab), then I am not sure that any one has resolved that beyond "just living with the line" if the set is only being used for "non-critical viewing". In your case, the initial display looked severely compromised with both lines and "blotches" which suggests the drivers may have been stressed significantly... not necessarily shorted but "less than perfect" electrically. The ultimate "perfect" outcome was unlikely.

[clabr]

Re: Sony LD-65X850-8c vertical lines on display problem

I am hoping those lines are in short outside of the COF on the opposite side touching by some residue left by the other COF I had removed.
But I understand it could very well be something inside the remaining COF determined by the problems the other COF had.
But I will see.