Late model "40 RCA LED LCD, upper 1/3 screen distortion, no T-Con board

[NorthernCrow]

Greetings,

I have a quick question for some of the more experienced techs out there.
(my background: I do component level work and am somewhat experienced with TV repairs)

"40 RCA RLDED4030A-B-RK LED LCD TV, about 2 years old, the set experiences distortion in the upper 1/3 of the screen, distortion is not static (at least not all of it),
It appears as what seems to be fast rolling reflections of what is displayed on the lower screen sections and also some light colored horizontal lines.
A thing to note, if a large portion or all of the screen is black, then the distortion would almost be unnoticeable.
It appears right from power on, on the white background with the RCA logo.
Another note is that some times the screen will go black, disconnecting and reconnecting the LVDS cable brings the picture back.

This set uses one main board which incorporates all functions and has the LVDS cable going to the small board that is attached right to the LCD panel, it is attached with permanently bonded flex cables and cannot be removed from the panel in an easy way.
The board is only attached with 2 cables, and there are no more boards or flex circuits attached to the panel anywhere at all.
The panel appears to be made by Samsung, and the long and narrow LCD board contains the following ICs:
Samsung LTF62B0 (larger IC adjacent to the LVDS connector)
RT6929 & RT6930 (to the left of the LVDS connector)
My attempt to find info or datasheets on those ICs didnt yield anything useful.

Things attempted:
-Disconnecting some of the LVDS wires, which causes the image to either disappear or freeze (including the distortion) and fade away
-LOTS of wiggling while the set is operational, mainly of the long narrow board and ribbon cables
-Applying moderate heat with a heatgun to the board and the ICs
-Thorough inspection with magnifying glasses and good light for anything unusual on the LCD board
-Applying moderate heat to all outer sides of the LCD panel
Aside from the image disappearing completely in a few cases where I've heated up the ICs too much (and then coming back when they cool for a minute), no change at all has been noted in the distortion.

I would like to get some advice, whether the issue is possibly with one of the ICs on the long board attached to the panel, in which case I assume that I could replace it (the IC), or whether this can actually be a panel defect, since judging by the only two cables connecting it, I assume that a lot is going on inside the glasswork as well.

Please correct me if I'm wrong here, but I'm pretty sure that this type of interference wouldn't be caused by an issue on the main board or the controller on it.

Thanks in advance for any input, and please see the attached images.

[lonewolf55]

Re: Late model "40 RCA LED LCD, upper 1/3 screen distortion, no T-Con board

my guess would be Gate Drivers but others here may know the RCA better than I.

[tom66]

Re: Late model "40 RCA LED LCD, upper 1/3 screen distortion, no T-Con board

100% bad panel
It's a Samsung panel and this is a common failure.

[Davi.p]

Re: Late model "40 RCA LED LCD, upper 1/3 screen distortion, no T-Con board

The defect is in the Chip on glass, if it is present, or in side tabs, you can salvage the big part of the image but needed some patient work, do you have wish? Needed pictures of the sections of the tcon (long b.).. writings must be readable..

[NorthernCrow]

Re: Late model "40 RCA LED LCD, upper 1/3 screen distortion, no T-Con board

Thanks for your quick replies,
The panel doesn't have any side tabs or any visible chips...
I am attaching a few detailed photos (in sections) of the long board that is attached to the panel, as well as two photos showing where one ribbon connects to the panel and a pic of the panel's corner, showing that there really is nothing there to fiddle with.

If it is indeed a panel defect and I can perhaps do something about it and salvage a large portion of the display then I will be up for that, as I have nothing to lose here in this case, the TV can't be pleasantly watched in the condition it is currently in.

[Andrew F. Ali]

Re: Late model "40 RCA LED LCD, upper 1/3 screen distortion, no T-Con board

You could try the 'Cut off' method to block out unwanted Gate Driver signals.

[Davi.p]

Re: Late model "40 RCA LED LCD, upper 1/3 screen distortion, no T-Con board

OK, watch the first photo, there is a STVP testpoint, in the other side (not other face) of the board there must be another one but it's not caught on camera, first cut one of them and watch if the defect improve, if not then join back this and cut the other one, if you have luck your job is done..

for ALI: if you see cutoff with tape can't be made, the board is one piece..

[RJARRRPCGP]

Re: Late model "40 RCA LED LCD, upper 1/3 screen distortion, no T-Con board

Is Samsung going the way of Sharp? Shit like this was probably why the Sharp TV division was sold to Hisense!

Having to remove a panel driver to restore functionality, would explain Sharp getting sold to Hisense!

[NorthernCrow]

Re: Late model "40 RCA LED LCD, upper 1/3 screen distortion, no T-Con board

Thanks for the tip, Davi.p.
I've tried this method, first STVP point that was cut caused the panel to not display anything, it has been restored, then the one adjacent to the other ribbon was cut, at which point the distortion changed from severely on the top 1/3 of the screen to even faint lines all over the screen, it was a little better but still visible and far from an ideal image.
Then something happened, the trace of the previous STVP point that I've cut and repaired has burned (I first smelled and then saw it light up in orange), I've repaired it again but from that point on the panel would display a little distortion on power up and won't display an image anymore.

Anyway, since it does indeed appear to be a panel issue, it's time for me to give up on this set.
The main board and backlight strips would be salvaged and the rest would be scrapped.

Thanks everyone for their input!

[RJARRRPCGP]

Re: Late model "40 RCA LED LCD, upper 1/3 screen distortion, no T-Con board

Then something happened, the trace of the previous STVP point that I've cut and repaired has burned (I first smelled and then saw it light up in orange)

That, to me, would look like corroborating evidence of a panel short! More so than the screenshot that I saw! The screenshot to the most left and top left in the first post, would have me suspecting the T-con or the mainboard.

[Davi.p]

Re: Late model "40 RCA LED LCD, upper 1/3 screen distortion, no T-Con board

Hi, first excuse me because i noticed now the previous time i have watched bad the last of the 4 long board images, i said the VCST was not caught on camera... ehm i was watching on the left i don't know why, instead watching the right i see that there's no VCST t.p. so i guess this screen is one of the most cheap i ever seen therefore there's i think 1 only gate driver array, and it's on the side where VCST exists. If you remove the panel glass and flip over you can see that or those at the sides with a magnifier... In this case nothing can be done by humans, only ants with micro drills and soldering irons...

[jjanssen7]

Re: Late model "40 RCA LED LCD, upper 1/3 screen distortion, no T-Con board

"ants with micro drills and soldering irons..."

Haha. If you source those let me know, I could use a colony.

[RJARRRPCGP]

Re: Late model "40 RCA LED LCD, upper 1/3 screen distortion, no T-Con board

"ants with micro drills and soldering irons..."

Haha. If you source those let me know, I could use a colony.

That's how I feel with motherboards and video cards, L O L