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

[RouDeR]

Hey guys, I`ve started a new thread with similar(but not the same issue) with Local Dimming on High
https://eu.community.samsung.com/t5/tv/q800t-q900t-local-dimming-on-high-is-crushing-dark-colors-if/...

Please check it and report if you have this problem with the 4k models (I have only Q800T)

[Alekkk]

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@LCDeez wrote:

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@Alekkk wrote:

Posted a reply here and it got taken down as 'spam'. Because I mentioned that Q80R users also had this problem and have had to resort to using the service menu to fix it? Are you going to delete this one too?

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Is it the exact same issue?

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Seems like it to me. Global dimming problem (whole screen dims), not local dimming problem (which is about only diming localised parts of the screen) on inputs in Game mode. I've got a Q80T, so am not able to fix it they way they did because of things I probably can't express here. Not going to repost everything I wrote, but Samsung ought to make the global dimming threshold user configurable like they have for local dimming. Global dimming works well in Movie mode, poorly in everything else. Not confident they'll do anything if they never fixed it in their 2019 models.

[jayh89]

Hopefully with it being reported by @AntS, they will actually fix it. I'd be pretty upset if they don't as it has potential to ruin games. It would also appear to be an easy fix! 

The whole service menu thing is something I'm aware of but I wouldn't risk going in there personally. 

[Alekkk]

Yeah, hopefully everyone who notices this problem finds this thread, keeps the issue visible and amplifies our voices, like you've all been doing.

I don't think anybody actually wants to stuff around with the service menu, but some Samsung customers have had to resort to doing this because they want their expensive televisions to work properly. I've seen a lot of people complaining about Samsung's TV firmware and how it often gets worse rather than better, so it's hard to know how realistic this getting fixed is. That said, this is an obvious and repeatable problem, so should be easy to replicate and fix if someone at Samsung investigates it.

[Luke_H]

I was lucky enough to get my set from a good friend who works at Samsung, Ive raised the issue with him with my fair share of moaning. Its fair to say he's a little embarrased about the whole situation and has promised to raise it as a matter of urgency with managment. Ive also sent him links to this thread for refference. 

[jayh89]

I certainly won't be giving up with this issue. It absolutely needs fixed as soon as they can. Why spend all this money on a TV that is "great for gaming" when the game mode is basically broken!? I'm hopeful that a fix is coming

[Iskandarkebab]

I just noticed something. Its not that turning on Game motion + makes the bug dissapear, when you turn on this Mode the TV reduces brightness automatically, and keeps It like that all the session. If you compare brightness with and without this Mode, you Will notice a difference in brightness, and is the same brightness that the TV shows when the bug appears after 6 minutes without Game motion Mode. So its the same thing, brightness goes down in game mode whatever you do, but when playing with Game motion off, you have full brightness at the beginning, but It goes down after 6 mins, whether when  motionp on you have this downgrade on brightness since you turn It on, so you dont feel the annoying bug and your eyes get used to this brightness

[RouDeR]

@Iskandarkebab

Game Mode does not reduce brightness, you have Led Clear Motion (Black frame Insertion) enabled, disable it and the brightness is going to be the same as outside GM.

[Iskandarkebab]

Nope, I dont have led clear motion on. Im not talking about turning on Game Mode. But turning on Game motion plus, but without led clear motion. When you turn on this Mode TV turns black for a moment and reduces a bit of brightness, the same amount as in the bug, but you dont notice because It keeps like that all the time.

[jayh89]

I've used GMP with clear motion on and off and not really noticed much difference. I'd say GMP does decrease brightness a little but nothing major (that I've saw). The main issue is in normal game mode, GMP off, after 5/6 mins, the brightness visibly dims quite a lot. As someone said, it's global dimming (the whole screen) and not just patches. So it's very jarring and sudden and definitely isn't meant to happen!