Not you typical vertical line - Samsung UN60JU7100FXZC

[wrtech_hleung]

Hello All,

This is my first real post so excuse me for any lack of info. I have this 60" 4k LED TV with a blue line on the right side of the screen, this line doesn't go from top to the bottom but instead it fades out as you go about 3/4 of the way from the top... As you go from the top to bottom, it's kind of a gradual gradient until the line is gone or too faint to be visible. This line exist for all input sources and on every menu.

I have some basic electronics knowledge and did some research, so I have checked all the ribbon cables and the TABs. I have attached a close up photo of the TAB that connects to that pixel column as well, it looks in pretty good shape and touching it made no difference.

Any of you experts have encountered this or thoughts? This look too systematic to be a TCON board failure right?

[chrismurphy]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

screen fault. sorry

[budwich]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

try cleaning that tab cable connection / contact area. It looks like it is "contaminated".... some one was "washing the screen"... maybe :-)

[Davi.p]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

I don't know well how it works but it is possible that over than damaging the ribbon with chip the bad driving can have burnt all the column? This has more sense if someone has stupidly washed the screen, maybe the woman of the cleanings, i can't see because the tab photo is out of focus and dark..

[CapLeaker]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

nope, that isn't a TCon failure. I agree with budwich. When I look at the last picture, it looks contaminated to me too, as if some one had cleaned the screen with too much water / cleaner and it ran down, corroding stuff.

[wrtech_hleung]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

Thanks for the reply so far. I will go take some better photos with better lighting!

Here's the full story: I moved with this TV (in the box, but it went up/down the stairs without box at times) and then one man mounted this in an awkward above fireplace wall mount. It's all possible I stupidly over flexed the panel... Then I took it to a Samsung "authorized" service center, who just quoted me a panel and said he managed to get the line go away for a bit and then it came back. It's all possible somebody "washed" it in all these scenerios.

If I need to clean the TAB connection area what do I use? Is 99% isopropyl alcohol too harsh for the adhesive they use for the TAB?

[CapLeaker]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

there is very limited things that you can do. First off, does the line disappear or change a bit if you press on the tab bond? If there is a change, you can "shim" the tab bond with a piece of heat conducting rubber pad or similar. Other than that, by the time you get a new panel, you may be able to buy a new TV. there is nothing wrong with 99% alcohol to use as an electronics cleaner. That's what I use 99% of the time.

[Davi.p]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

I don't agree with Samsung center, the line is not all solid, so for now the only thing that comes in mind is the washing scenario. For the last question i have never used that alcool i dont' know but i think it's really unlikely a fault at mount of the tab, since all the colour info lines at mount controls all the columns of the tab at turn, so you would become to an entire band of a different colour if some of the colour lines of the minilvds was missing. the fault is at valley of the COF (chip on flat) where each pin controls one only column. I think the connection COF>panel or the COF itself is burnt, or at least is broken the trace on the glass. Bye.

[budwich]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

As capleaker says (me too), your unclear picture of the board connection appears to show contamination across a few track of the tab cable. You need to make all those connections appear to be the same by "gently cleaning" them with alcohol and maybe an eraser (clean pencil eraser).... hope that it works. Otherwise, as davi.p indicates the next area of "possibility" is the chip that is mounted on the cable itself which you might see and might be where you can apply some form of thermal pad / pressure (gently) to impact its operation.

[Davi.p]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

sorry i say "mount" , i mean "mountain"

[wrtech_hleung]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

I think I have to agree the failure is at the valley of the fan out chain where it drives only a single column. I learned something new today... didn't know there's a chip on the other side of the film. I did try to clean both sides of the TAB, the COF, and even the area of the rigid PCB near the affected area with alcohol but nothing worked. Pressing the area didn't make a difference either

I still want to learn how this thing actually works though. My understanding is to have a gradient line like mine, the blue colour column and row must be "stuck on" in varying degrees of blue (from 255 to 0 as you go top to bottom for 8bits). Does the COF act as column and row demultiplexers that just rapidly update each pixel in its responsible area to create an illusion of 60/120Hz refresh rate? They look like they are CMOS like chips perfectly suited for that because of area density.

[Davi.p]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

the cof is basicly a shift register , an a/d converter and some other, i don't remember, it drives the drains of the pixel's mosfets, it decides how much current to flow therefore the grey level of each subpixel. Watching better pictures i see that ribbons are on the bottom side and the column is rightly driven for some inches then fades away to dead pixels, so another scenario is a blow on the screen that have left glass intact and pixels dead, i've seen this on a monitor...

[budwich]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

the first picture appears to show some "issue" with the lines heading up from the middle area of the "array"... there are about 3 or 4 in a row which appear to be missing / cut / melted??? and a couple of others closer to the right side with the same appearance.

[wrtech_hleung]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

Davi.p thanks for your education. Your description would make sense, it's basically a deserializer attached to a current steering d/a for the pixel mosfets. Since the I/V curve is so non-linear for a mosfet, is there something truly called a 10bit panel out there even with some fancy linearization DSP?? Just planning ahead while I search for a TV to buy on black friday... all this HDR10 stuff might be just a waste of money.

So the COF drives the entire column and it has the same number of wires to drive each of the 2160 pixels in the column? I have a feeling I missing something because that's not very efficient use of routing real estate. I see some sort of COF on the ends of some of the rows too, what do those do?

[Davi.p]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

First i've said A/D converter, not is a D/A converter, then i dont understand well the DSP thing nor HDR10 tag, i'm not real a circuit expert, i only try to suggest you not to buy especially Samsung tvs 'cause as you can see from the history of the site is one of first in the list of self damaging lcd panels, not really repairable, they use always those crappy SAMWHA / SAMYOUNG capacitors (Samsung brand, and maybe them are the start of any issues), instead you can choose for a better quality components brand like Panasonic, Sony, maybe Sharp (higher level ones, not entry level), at least in italy them appears very rarely on the second hand market as faulty.

The COF has some control pins (for example the gamma correction pins, clock, power lines) and about 6 or more traces/bits per colour RGB at input and has one output per column, so if the COFs are 8 for example, in a fullhd lcd, each cof has 1900(h resol.)/8(num. of COFs)*3(RGB subpixel columns) outputs. Them only drives the drain, the Gates are selected at turn by side COFs (they outputs only 2 states, ON or OFF, when top/bottom cofs have an analog 6/8 bit "grayscale" output level)

Ah sorry again, the top/bottom drivers drives the sources not the drains, e-ehm...

[budwich]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

do you other tab cables on the bottom look like this???? It doesn't look right.

[wrtech_hleung]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

budwich, good eyes!

I don't even realize that's what you were pointing to, i kept thinking you were talking about the gold fingers. I will go home tonight and check... it does look like shorted lines in that picture.. i hope it's just an optical illusion

[budwich]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

Of course, it doesn't really do you much good as they are still not repairable... BUT... you never know. Depending on what they actually represent and how they are damage, a "steady hand" and "good eyes" might be able to do something... maybe. Just a hope.

[Davi.p]

Re: Not you typical vertical line - Samsung UN60JU7100FXZC

Don't hope much, i guess them are a normal design..