I have created this post to explain the defects that I have recently noticed in my Samsung UE48JS8500 TV. I must say that the goal of this post is not to search for a solution to my problem (I think there is none), but to show other potential buyers what they might be facing when purchasing a high-end Samsung TV (~2000 euros) with high specs of brightness and luminosity.
My TV is only 5 years old and, as you can see in the attached pictures, the picture quality is quite poor due to the degradation of the display. In my opinion, this is caused by a combination of overdriving the backlight LEDs and deficient cooling, just to achieve the levels of brightness that Samsung claims to provide.
Since the TV is out-of-warranty, Samsung just redirects me to the local technical service, whose solution is to change the display at a cost of 700 euros. This, of course, sounds to me like a joke, taking into account that the TV had a price of around 2000 euros, and it was bought specifically to get the best possible picture quality. Comparing to what I have seen so far, the burn-in issues of OLED TVs are negligible, and this is the technology (or an equivalent one) that I will probably consider in the future when changing my current TV.
I hope my experience is useful for someone.
This is the explanation for all the defects that I have noticed in my TV:
1.- There is a group of pixels on the left side of the TV that turn off slowly from the moment the TV is turned on. This issue can be seen after using the TV for 30 minutes approximately, and the problem increases to a maximum until the TV is turned off for a prolonged period. These are not dead pixels since the issues come and goes. In my opinion, the root cause is the backlight LEDs overheating on that side. See Image-1 and Image-4.
2.- Around ¼ of the screen (top left corner) is much darker like burnt. I am not referring to image retention but literally burnt. See Images-2 and Image-4.
3.- Small areas of the screen close to the left border are much brighter than the rest of the display. See Image-3.
4.- The TV has a backlight bleed on both sides. See Image-3 and Image-4.