2020 QLED T models (Q80T, Q90T, Q800T, Q900T) HDR game mode brightness / local dimming bug

[Rauttis]

I bought a Q80T a couple of days ago and have noticed a really annoying issue when using the tv with the combination of HDR and game mode.

I'm fairly certain this is a software bug in the TV since I can reproduce this issue with 100% accuracy, and it happens on the dot at the same moment every time. It's basically on a timer.

Basically when the game is displaying a HDR signal and game mode is enabled, exactly after 6 minutes the brightness of the TV suddenly drops by around 20 (50 -> 30). The value of brightness setting doesn't actually change however. Messing with the brightness setting does not restore the brightness to it's original state, but changing the local dimming setting from standard to low and then back to standard does. Switching game mode off and then back on also fixes the issue, but then it happens again EXACTLY after 6 minutes (I've timed this with a stopwatch).

Has anyone else experienced this issue? Or can someone maybe test this on their TV to see if you can reproduce it?

Exact repro steps on how I can reproduce this 100% of the time on the PS4 Pro:

1. Set brightness to max (50)
2. Set local dimming to standard (bug happens on high as well)
3. Enable game mode
4. Turn off game motion plus
5. Turn off intelligent mode and all the brightness related settings in eco settings, as these can influence the brightness level of the tv.
6. Launch a game that runs in HDR
7. Start your stopwatch
8. Do whatever you want in the game or you can also go back to PS4 menus, find a bright scene where you can notice a brightness drop easily
9. When the stopwatch hits 6 minutes, you should see the TVs brightness suddenly drop by a large amount. By eye the brightness drop seems about equal to dropping the brightness from 50 -> 30 by hand.
10. Go to picture settings and set local dimming to low (brightness does not change)
11. Set local dimming back to standard (brightness suddenly jumps to the original level. Brightness can be restored by switching input away and back as well, or by disabling and re-enabling game mode)
12. And again after EXACTLY 6 minutes the bug again repeats and the brightness drops down again

Some other notes: The PS4 has a screensaver that basically dims the screen if it is idle for a while. This is not the cause of this, this happens even when the console is in active use and the brightness can be restored temporarily by changing the local dimming setting like described above. I have not managed to reproduce this issue with game mode off, so it seems to be related to game mode.

Software version: 1304

[Peto Pedro]

Actually the sensors are on top corners... tiny 1mm or half cut 1mm of black tape square and tape it on both upper left and upper right corner of the screen .. U will see micro dots... 

[Doog]

Wouldn't sticking tape over the light sensor make the TV think the room was really dark, and thus making it produce a darker picture? I would think the TV would be designed to provide a brighter picture when it is in a really bright environment, and as my screen problem is that it dims automatically, I would think covering the sensors would actually make it worse?

[Peto Pedro]

 hmm so try anyway, try  to clean them ... or check them they might be faulty 

[Peto Pedro]

I have everything turned off  in that eco settings

[Doog]

yeah it's not as simple as that unfortunately. If you read through the 200-odd pages here complaining about dimming issues then unfortunately you'll see it's not as simple as changing the settings. Covering the sensors also makes no difference.

What I really want to know is - what did the many people in this thread who were extremely unhappy with this TV do with it in the end? Did everyone sell up and get rid?

[kaveh serousheh]

Samsung Q800t 2020 75”

I’ve been having this issue back and forth.. i dont know if i have found the solution for me but it seems to have to do something with either setting to 120hz or game mode on or off (HGIG). i’ve read somewhere that the tv has something called ABL(?), and they say that the TV handling this ”ABL” very good. it basically protects the compontents in the Tv for being overheated.  Try to set your settings to 4k 60hz instead with game mode On/off (i prefer off). or if you insist set it on 4k 120hz, game mode on (HGIG on), set your HDR calibration in xbox : 1 scene: Lowest black as possible. 2 scene: 1400 nits ( 24 times right). each click represents 50 nits and it starts with 0 = 300nits. 3 scene: the same as the 2nd scene. 

But i have so much other problems with my TV regarding eArc, grey stripe line in middle of tv so i have aprox 50 errands with samsung. Finally a technican har planning to come 16th November for changing the display. if your warranty still exists.. use it. if they tell you something similar like the problem isn”t theirs.. speak with you local consumer right department (?). in Sweden they call Konsumentverket 😂

[Doog]

My issue is much more simple even than game mode on/off etc.. As soon as I turn the TV on it looks great, really bright, and then after around 10 seconds it dims really noticeably and stays that way. No adjustment can make it brighter again. On a sunny day it is almost unwatchable.

I spoke to a Samsung guy today and he just talked to me like I was stupid and said "it is supposed to do that, it's energy saving".. which makes absolutely no sense as I have all the energy savers turned off, it does the same thing regardless of how bright the room is, and why on earth would a TV turn on nice and bright, wait 10 seconds and then just go 30-40% darker?

I asked him if he was aware off the 200 page thread on the Samsung forum and of course he said he was not

[kaveh serousheh]

Oh okay! I  would say rather the samsung support is stupid than you. my experience with samsung support is ****.. one time i told them if the tv should support LPCM? and the answer was ” yeah this tv supports dolby atmos, it is something that throws the sound from wall to wall..😁 

i Have also noticed that if you change the gamma or shadowdetail down 1 level, the display will dim after few minutes dramaticly. if you have done that- try to set it at ”0” again. I’m mistaking that all this have to do something with the ”ABL= auto brightness limitation” function, a way the TV protects the other compontents for being overheated. after all my tv for example has class ”G” for energyconsumption.   Try also to put the power cord directly to the wall instead. 

[Peto Pedro]

I know I know but if I would have something in warranty I woul dnever ever bother spending time reading forums  straight send back for refund ...

Try turn the HDR off it is useels anyway

[Peto Pedro]

I have connected my PC RiG  and I would never EVER go back to 60 Hz  HORRIBLE !  Tearing  

I have desktop 4k freesync (vrr 120Hz) HDR off otherwise  picture is awful I have amazing picture in Windows without HDR