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

[jdk2087]

What are your full settings? So you’re saying, in HDR with game mode on and picture set go native, you’re not experiencing any screen dimming? That’s with local dimming on high? I feel like if that was true someone would have found that out as that would technically be a decent work around that doesn’t sacrifice too much. So yea, what are your full picture settings? 

[Jihionfly]

Outside game mode you have quite more input lag..so no solution for gaming..

[jdk2087]

Got it. I was thinking he was saying that IN game mode with native picture on that it wasn’t doing it. Thought that maybe whatever picture mode you had selected was causing the dimming. 

[Soccercrazy1]

Yeah I was using natural preset to see how local dimming should work. I only get the brightness dimming bug when my picture is set to standard picture preset. I do not get the bug in game mode. I also do not get the brightness dimming bug in the natural picture preset. It is not a solution for anything related to game mode as someone mentioned the input lag is too high. However, It will show you how local dimming should be performing in game mode. I have pics in my thread and hope you support it so samsung can fix it. I have a Sony 900h in another room and it's local dimming in game mode is exactly the same as out of game mode so Samsung has no excuses. If your local dimming in game mode looks like the pics in my thread please post on it.

https://us.community.samsung.com/t5/Qled-and-Frame/Q90t-game-mode-local-dimming-is-broken/td-p/14391...

[jdk2087]

Sadly, I’ve turned GMP on for now so that I don’t get the dimming bug in game mode at all. Also so that I can utilize local dimming. It sucks, but it’s our only decent option at the moment. That or mess with the TVs service menu and someone was saying earlier in this thread that not even that is really a fix for the issue. *Hopefully* this September 26th update we’ve now been given by Suriya is true. 

I just want the tv fixed. I love it and it would be the perfect tv for me if it weren’t for this issue. 

Off-topic: Could anyone provide me with an overall good picture settings for game mode HDR/SDR and tv(movie/shows) HDR/SDR? I feel like the ones on the AVS forums just don’t wow me like they should. And no ones posted their game mode custom settings. I see some of y’all post your tv screens(Q80T, etc.) with WAY better looking colors than the same tv I have. Any help would be greatly appreciated! 

[Soccercrazy1]

My local dimming in game mode is exactly the same whether game motion plus is on or off. Is yours different?

[LCDeez]

Yup, no dimming with GMP on. It seems like it’s dimmed automatically though, like it’s closer to what happens after 6 minutes with it off.

[SidL]

This is really not normal, because before the 1304 update when GMP OFF the local dimming function worked perfectly. Now it only works normally if you activate GMP, which sucks because the image is full of invertghosting in yellow, green and purple.

[SidL]

No. if GMP is disabled, the local dimming does not work correctly

[Soccercrazy1]

So your saying activitating Game Motion Plus makes local dimming work in game mode the same way it works outside game mode. Is this post update or pre update. Was local dimming good at a point before in game mode. Can you talk about it in this thread so that issue becomes popular as well and we get this brightness dimming bug fixed and the local dimmi g fixed as well. 

https://us.community.samsung.com/t5/Qled-and-Frame/Q90t-game-mode-local-dimming-is-broken/td-p/14391...