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Old 09-15-2019, 12:28 PM   #1
clabr
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Question Sony LD-65X850-8c vertical lines on display problem

A friend of mine brought in a Sony KD-65X850-8c for repairs.
I have some experience with TV repairs, and I am a DIY type of guy so I am trying to solve this problem if possible.
But I need your help and knowledge, as well.

This is the problem it has (vertical lines on the whole screen)
IMG_20190915_142638_2.jpg (first pic in attachments)

It is the same, from the bootup process (logo), even with or without any signal input.
The vertical lines are more or less on the whole screen, and do change with the animation.

Where could this problem come from?
The panel or the t-con board ?

Right now (in my pictures) the signal it has, is from a HDMI input (laptop).
The TV is upside down, in order to have access to the ribbons of the T-con and buffer boards.

It's a big 65'' TV, thus the T-con board (t650qvn04.0) has 4 outputs with 4 ribbons that go to 4 panel buffer boards (linked in series with another 2 ribbons).
I numbered the ribbons, like this, for the forthcoming pictures examples.
IMG_20190915_193405_2.jpg (2nd pic in attachments)

Right now ribbon nr 1. is on the right, but with the display on ribbon nr. 1 is on the left (in order to clarify the examples)

I tried cleaning all the ribbon connections and also pressing the tabs on the buffer boards. But no change whatsoever.

Then, I tried powering it up with disconnected ribbons (T-con to buffer board and between buffer boards) and I got picture on display.

This is what the display looks like with:

- with only ribbon nr. 1 disconnected:
IMG_20190915_141332_2.jpg (3rd pic in attach)
remember, right now, i.e (in the pictures with the display on) ribbon 1 and 1b are on the left part of the TV.
- with both 1 and 2 disconnected:
IMG_20190915_141515_2.jpg
- with only 2 disconnected:
IMG_20190915_141850_2.jpg
- with 3 disconnected
IMG_20190915_142141_2.jpg
- with 3 and 4 disconnected:
IMG_20190915_142231_2.jpg
- with nr 4 disconnected:
IMG_20190915_142404_2.jpg
- with 1b disconnected:
IMG_20190915_143100_2.jpg
- with 2b disconnected:
IMG_20190915_143411_2.jpg (last pic in attach)

There are also some artefacts though (with a zoom on some images, it can be seen)
2 horizontal lines
One is more visible than the other.

Do this examples prove anything?
Should I go with changing (and investing in) the T-Con board?

Thank you.
Attached Images
File Type: jpg IMG_20190915_142638_2.jpg (433.6 KB, 18 views)
File Type: jpg IMG_20190915_193405_2.jpg (322.3 KB, 25 views)
File Type: jpg IMG_20190915_141332_2.jpg (288.9 KB, 22 views)
File Type: jpg IMG_20190915_141515_2.jpg (301.5 KB, 17 views)
File Type: jpg IMG_20190915_141850_2.jpg (246.8 KB, 18 views)
File Type: jpg IMG_20190915_142141_2.jpg (223.0 KB, 17 views)
File Type: jpg IMG_20190915_142231_2.jpg (271.1 KB, 16 views)
File Type: jpg IMG_20190915_142404_2.jpg (303.3 KB, 14 views)
File Type: jpg IMG_20190915_143100_2.jpg (331.9 KB, 18 views)
File Type: jpg IMG_20190915_143411_2.jpg (394.1 KB, 25 views)
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Old 09-16-2019, 10:03 AM   #2
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Default Re: Sony LD-65X850-8c vertical lines on display problem

along each side of the panel, are there tab bonds? these can usually only be seen from the front with the bezel removed. IF so, check to see if any look like they are heated. Similarly there are tab bonds on the bottom, going from the bottom edge boards to the panel... do any of those look heated. Gently feel them with your finger to notice any difference.

As for the "2 horizontal lines"... not sure i see what you are saying... the picture you have is too busy. Try inputting a "standard test pattery" (eg. smpted color bars)... this may highlight things better.
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Old 09-16-2019, 11:02 AM   #3
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Default Re: Sony LD-65X850-8c vertical lines on display problem

with yours photos by disconnect 1b and 2b it lead to as suggested before , remove the bezel and inspect the side bonds and the down one too include the LCD self if you have small crack at any of lcd print film. you can see it at the bottom of LCD where the taps connected
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Old 09-17-2019, 09:35 AM   #4
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Default Re: Sony LD-65X850-8c vertical lines on display problem

Quote:
Originally Posted by budwich View Post
along each side of the panel, are there tab bonds? these can usually only be seen from the front with the bezel removed. IF so, check to see if any look like they are heated. Similarly there are tab bonds on the bottom, going from the bottom edge boards to the panel... do any of those look heated. Gently feel them with your finger to notice any difference.

As for the "2 horizontal lines"... not sure i see what you are saying... the picture you have is too busy. Try inputting a "standard test pattery" (eg. smpted color bars)... this may highlight things better.
Thanks for pointing that out.
I didn't think there could be tabs on the sides as well. I don't have much experice with big LCD panels.

Right now I only removed the side bezels and checked them visually.
I will remove the upper bezel also, when I will have more time
and I will check them thoroughly, visualy and by fealing, pressing them
I will get back with what I've found.

Here is a picture more suitable for distinguising those 2 lines that are always present.
Attached Images
File Type: jpg IMG_20190917_161013_2.jpg (63.3 KB, 16 views)
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Old 09-17-2019, 10:26 AM   #5
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Default Re: Sony LD-65X850-8c vertical lines on display problem

Sometimes a shim on the loose tab bond will work if it is not getting good contact and sometimes this will work, that is IF it's a tab bond issue: https://www.youtube.com/watch?v=ZJwu7cwrttk

Last edited by nomoresonys; 09-17-2019 at 10:37 AM..
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Old 09-17-2019, 12:41 PM   #6
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Default Re: Sony LD-65X850-8c vertical lines on display problem

Quote:
Originally Posted by clabr View Post
Thanks for pointing that out.
I didn't think there could be tabs on the sides as well. I don't have much experice with big LCD panels.

Right now I only removed the side bezels and checked them visually.
I will remove the upper bezel also, when I will have more time
and I will check them thoroughly, visualy and by fealing, pressing them
I will get back with what I've found.

Here is a picture more suitable for distinguising those 2 lines that are always present.
so this picture does show the two lines more clearly. It appears that there are at least issues with the side tab drivers / bonds.... but notice the color "blotches" in the area where one would expect "clean" / uniform color. This may indicate a problem with the edge boards... possibly a weak smd capacitor or resistor. The significant dark "blotching" in the first pictures is also a worry. These to me indicate a problem somewhere in the bottom boards.

As you said, check the tabs on the side first and then again on the bottom boards also.

Last edited by budwich; 09-17-2019 at 12:43 PM..
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Old 09-19-2019, 11:50 AM   #7
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Default Re: Sony LD-65X850-8c vertical lines on display problem

Quote:
Originally Posted by budwich View Post
so this picture does show the two lines more clearly. It appears that there are at least issues with the side tab drivers / bonds.... but notice the color "blotches" in the area where one would expect "clean" / uniform color. This may indicate a problem with the edge boards... possibly a weak smd capacitor or resistor. The significant dark "blotching" in the first pictures is also a worry. These to me indicate a problem somewhere in the bottom boards.

As you said, check the tabs on the side first and then again on the bottom boards also.
When you say, bottom boards, I guess you are reffering to the 4 PCB driver boards (those that have 4 tab bonds that go to the panel on each of them)?
which in my initial thread post pictures appear on top
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Old 09-19-2019, 11:57 AM   #8
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Default Re: Sony LD-65X850-8c vertical lines on display problem

Today I managed to take a closer look at the TV.

So... there are 10 COFs on each side of the panel (where I took off the bezels).

With the TV on (obviously), I started to press (feel) them.
No change to the screen, and none of them was getting hot.

One of the two artefacts, lines disappeared though. I don't know how and why, but pretty sure it happened while I was trying to get the bezels out.
It surely happened before I started the process of feeling , pressing the COFs, because then I wasn't paying much attention to the panel.

After that, to my surprise, after around 10-15min with the TV on and a HDMI signal source connected, I turned off and then on the TV again, and there was a good picture on the whole screen (no vertical lines anymore, ony one horizontal artefact).

And only now, with a good picture on whole screen, I could feel that 2 COFs are getting hot.
It's the 3rd COF from the base, on each side. Placed somewhere where the 2 lines (artefacts) were (now there is just one).
One of them is getting very hot (arround 80-90 i guess), and one just a bit (arround 40-50)
All others have a pretty cool temperature.

While there are vertical lines on screen none of them was hot.
If I turn off the TV for a longer period (5-10min) and then on, the vertical lines reappear and the COFs are not getting hot.

If I turn on the TV for 10-15min with the HDMI source in , turn off then on the TV imediatly, only then I could get a good picture again.
Only now those 2 COFs are getting hot.

Thanks for your help and info (especially budwich and to the others as well)
At least now I know where the source of the problem is, and that it is not the T-con (so I won't invest in that anymore)

The question is what can I do now, that I know which COF is getting hot?
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Old 09-19-2019, 12:53 PM   #9
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Default Re: Sony LD-65X850-8c vertical lines on display problem

can you post a picture of one side to give us an idea of what you are dealing with in terms of tabs?

The tabs will likely only get hot when they are trying to do something.... when you see verticals lines, basically the side tabs at that point are doing little to nothing.

The horizontal lines are likely the area / tabs that are in question.

NOTE: now that you kind of got somewhere... don't go too fast... there are some things that you can do to save the set... maybe. But at the same time, going too fast, you might go the wrong way and basically end up with a "bad" set. There is one method that is a "tape cutoff" method which uses tape to block signals at the tcon to shut off a set of "side drivers". This method is usually used when there are no physical side tabs but drivers in the panel. It is a "try and test the amount of tape to use" and is thus reversible at any point because all you have to do is removed the piece of tape.... assuming of course, you don't damage the tcon connector during your "play". The other method is a "tab removal" method. This is quite drastic and should only be done as a last resort as it is not reversible. Once tabs are removing, they cannot be replaced. To this end, you need to determine which side is bad and go from there. Do some reading around tab removal and tape cutoff to get an idea of things.

Last edited by budwich; 09-19-2019 at 01:00 PM..
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Old 09-19-2019, 01:48 PM   #10
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Default Re: Sony LD-65X850-8c vertical lines on display problem

One other thing to help identify where the problem lies.... you mentioned there are FOUR bottom "edge boards" on the set. IF this is correct, there are TWO per half of the panel. Each "pair" is interconnected with a "U" flex ribbon cable that is "unclampable" much like the tcon cables. You are able to disconnect the interconnection point therein. By doing that you can isolate the "far side" of the panel. IF you do this, one side at a time, this may tell where your problem lies. Of course, do any cable "changes" with the power OFF.
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Old 09-20-2019, 09:35 AM   #11
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Default Re: Sony LD-65X850-8c vertical lines on display problem

Quote:
Originally Posted by budwich View Post
One other thing to help identify where the problem lies.... you mentioned there are FOUR bottom "edge boards" on the set. IF this is correct, there are TWO per half of the panel. Each "pair" is interconnected with a "U" flex ribbon cable that is "unclampable" much like the tcon cables. You are able to disconnect the interconnection point therein. By doing that you can isolate the "far side" of the panel. IF you do this, one side at a time, this may tell where your problem lies. Of course, do any cable "changes" with the power OFF.
In my initial post, I did explaind how the TV reacts with those "U" flex cables disconnected (I called them 1b and 2b (as it can be seen in my 2nd attached picture))

The TV has good picture on 2/3rds of it with those disconnected (one at a time).
The problem, vertical lines on screen, arises only with ribbon 2 disconnected and also with ribbon 3 disconnected (all other ribbons including the U one are in)

At that time I didn't know about the side tabs, gate drives, or how are they called.

As I said before , there are 10 of them on each side
and 2 of them are getting hot

They are produced by RAYDIUM and have this code RM76160FA.ODF
(As it can be seen from the attachments, I hope)

These days I researched about COFs and I also came across about those 2 methods you mention, and about bypassing method, as well.

I can't find any pinout for those test points though.

I don't know how I could find the equivalent on the edge pcb boards of the lines that come to those tabs that are getting hot.
What method can I try to fix this, and what is the logic of it?
What is the logic of them getting hot, is it a short in those lines along the edge of the screen?
Also is it the TCon that is not letting the whole screen to function, when it senses a problem with those COFs?

I surely should try to get a good answer to questions before I try something irreversible.

There is no rush; the owner gave me enough time maybe even more than a month, to try something and maybe fix it.
Attached Images
File Type: jpg IMG_20190920_145337.jpg (310.3 KB, 8 views)
File Type: jpg IMG_20190920_145601.jpg (378.4 KB, 10 views)

Last edited by clabr; 09-20-2019 at 09:39 AM..
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Old 09-20-2019, 10:08 AM   #12
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Default Re: Sony LD-65X850-8c vertical lines on display problem

Let's back up a bit. Forget disconnecting any cabling at the tcon. Do the test again with disconnecting on of the "u" cables and post a picture using a good input of a test pattern. Repeat the same test with the other "u" cable. go from there with the results.
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Old 09-21-2019, 01:23 AM   #13
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Default Re: Sony LD-65X850-8c vertical lines on display problem

The test with the ones you call "u" cables it's been already done and it's very well explained by the poster, that test did not show which side has the fault and since the hot cofs are on both sides it's realistic to think both sides are faulty, the fault it's caused by shorted cofs, i don't think that in Romania there are labs that replaces those cofs, so this is a lost cause.. in think..
Maybe the only one resource is to try to cut the output line of the 2 faulty lines, that exits the cofs versus the screen, using a sharp needle, this will end in a surely shut off line but with the rest visible.. MAYBE!

Last edited by Davi.p; 09-21-2019 at 01:31 AM..
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Old 09-21-2019, 11:48 AM   #14
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Default Re: Sony LD-65X850-8c vertical lines on display problem

The display signal that he posted is too busy to identify sides. Yes both sides are warm, one more than the other according to the poster... that could because one side is dragging down the other. Poster, redo the test as suggested... it costs nothing. or follow the "other advice". good luck.
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Old 09-21-2019, 01:14 PM   #15
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Default Re: Sony LD-65X850-8c vertical lines on display problem

Quote:
Originally Posted by budwich View Post
The display signal that he posted is too busy to identify sides. Yes both sides are warm, one more than the other according to the poster... that could because one side is dragging down the other. Poster, redo the test as suggested... it costs nothing. or follow the "other advice". good luck.
I will do it soon budwich, just haven't got enough time for it right now.
I will post pictures with a better display signal and also pictures of the side COFs (all 10 of them on a side)
The side gate driver IC technology looks similar to that in the video

I can't seem to find the pinouts of the gate driver IC anywhere on the internet.

Thanks for your and other's help!

Meanwhile I've found probably a pretty similar problem and solution in a video on youtube
https://www.youtube.com/watch?v=ooaM7PnGUfM

Last edited by clabr; 09-21-2019 at 01:15 PM..
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Old 09-21-2019, 01:42 PM   #16
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Default Re: Sony LD-65X850-8c vertical lines on display problem

Yes seen those type videos several times, too bad you didn't find one in English, would be much easier to follow.
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Old 09-21-2019, 01:50 PM   #17
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Default Re: Sony LD-65X850-8c vertical lines on display problem

I think that one COF is broken for the line 1, the other one for the line 2, since it is very uncommon that with only one line the opposite COFs are broken both, as for the tip of the needle, it's only a little suggestion, never tried it by myself, it can be an impossible thing 'cause counting the lines that exits from the COF it's very hard or impossible, maybe only with a USB microscope, and a realtime video graphic editing, the pinout is not needed, the line to be stopped is one of the many and many that goes out from the chip and reach the screen, not only from one side but part also in the outer side, you can even try to cut some of the surrounding tracks if the task is impossible.. bye..

Last edited by Davi.p; 09-21-2019 at 01:51 PM..
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Old 11-14-2019, 02:03 AM   #18
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Default Re: Sony LD-65X850-8c vertical lines on display problem

Hello everyone.
Sorry for the delayed answer, but I was cut up with some personal problems and the owner of the TV left the country (so he didn't need it)

As I mentioned in posts before, the culprit of the problem (the fault) most probably lies in one gate driver that is getting hot (the third from the left side. they are 10 drivers on both sides)
I reckon because the driver malfunctioned and it is in short, the T-CON does not function as it should.

I think I would try and cut out that particular gate driver or try and cut the lines that go the gate drivers method.

Anyone that knows pretty sure and cares to help me, please tell me what lines that have a connection to the gate drives, should I try and cut? (so that, I would deactivate the whole left side).
I have attached all the test points from the panel PCBs in a txt file.
From LCD repair manuals I understand that older TV models usually have lines names as CKB, CKVB, STVP, that should be cut. (lines that go to the shift register on the gate drivers)
But on this particular large display with AUO chips, these lines are not named the same.
From my dilettante research, I guess YDIO1, YDIO2, YCLK1, YCLK2, or/and some OE named lines, go to gate drivers. Am I right?

Also, I know I could try and just cut out that particular gate driver.
Is it OK to cut out just one driver on a side, and not all the gate drivers from that side?

Will the TV image be the same (brightness, contrast, definition) after disabling one gate driver or all from a side?
Is it better to cut out (or deactivate) all the drivers from one side, and why?

I understand that bigger displays usually have gate drivers on both sides.
Are these gate drivers redundant, are they used as a backup?
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Old 11-14-2019, 03:55 AM   #19
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Default Re: Sony LD-65X850-8c vertical lines on display problem

Maybe try the "cut tape" method, works for some, may have to adjust the size or position of the tape: https://www.youtube.com/watch?v=j7vl7-vZEL8
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Old 11-14-2019, 04:42 AM   #20
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Default Re: Sony LD-65X850-8c vertical lines on display problem

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Originally Posted by nomoresonys View Post
Maybe try the "cut tape" method, works for some, may have to adjust the size or position of the tape: https://www.youtube.com/watch?v=j7vl7-vZEL8
Yeah, I know about that (that particular link video is not relevant though).

It is the third method to deal with bad gate drivers, the tape cut method.

I didn't mention it because I don't think I could possibly be lucky enough to find the right pins to cover with tape (there is no schematics around for the Tcon as far as I know, and it has 4 large connections, like in attachment)

I guess I should rather try the cut line method or removing the gate driver (maybe the whole left side gate drivers?)
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