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

[KindOldRaven]

Results in a very dark image. Especially if VRR is enabled, which already provides a much, much darker image than without VRR/Freesync 😜 Then again if I can't find a fix for my Freesync/VRR issues I'll request a replacement set and will experiment with that one 😛 

[LCDeez]

Even with contrast enhancer on high? 

[KindOldRaven]

It's not that type of 'dark'. It's dark as if someone tried to set RGB Gamma to 2.5. That type of dark. So enabling contrast enhancer still crushes blacks and blows out highlights as long as VRR/Freesync is enabled. I haven't heard anyone else having this issue so I guess I've got a borked panel 😜 

[jayh89]

This almost certainly isn't a heating issue. It's appears to be a simple bug in the firmware. I've spoke to people that tested the TV and they didn't even find this issue so I think it has been introduced in a future firmware update from when the TV was originally released. 

[Suriya]

One more thing i have noticed.

Brightness level of Game motion plus ON looks dim compared to the Game motion OFF.

Brigthness of GMP ON Exactly look like the brigthness level after the dimming bug happened. You can clearly see the difference by using any brighter scene ex: snow area.

Also when GMP ON try switching local dimming to low nothing will happen. 

Very shame on SAMSUNG never ever say or advertise anything as a FLAGSHIP. Brightness is the only thing have bought this TV really disappointed.

Going to creat separate thread for this. And one samsung senior engineer visited yesterday and convince me to live with this bug.

Pls compare the brigthness level as i mentioned and rise your voice guys.

[Luke_H]

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@Suriya wrote:

Going to creat separate thread for this. And one samsung senior engineer visited yesterday and convince me to live with this bug.

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@Suriya wrote:

One more thing i have noticed.

Brightness level of Game motion plus ON looks dim compared to the Game motion OFF.

Brigthness of GMP ON Exactly look like the brigthness level after the dimming bug happened. You can clearly see the difference by using any brighter scene ex: snow area.

Also when GMP ON try switching local dimming to low nothing will happen. 

Very shame on SAMSUNG never ever say or advertise anything as a FLAGSHIP. Brightness is the only thing have bought this TV really disappointed.

Going to creat separate thread for this. And one samsung senior engineer visited yesterday and convince me to live with this bug.

Pls compare the brigthness level as i mentioned and rise your voice guys.

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Well thats pretty terrible support, no??????????

[corvuss]

I'm from spain,bought a q95t (which it's the same panel of q90t) 15 days ago,i knew about ghosting problem but since samsung fixed it i decided to buy this tv and now this dimming bug is making me crazy,i also bought this tv for its peak brightness and gaming features and none of this works well with freesync darkening all picture and this new auto dimming bug.
I was playing this 2 weeks on a ps4 pro spiderman and in my case,auto dim happens randomly,sometimes after every 6 min,sometimes it doesn't happen for 2 hours or more so the overheating theory ...i dont know guys but spending 1,5k€ in my country  to fight all this problems is very annoying,hope this get fixed very very soon

[corvuss]

i think there is  a relation between having low input lag+brightness+game mode ,i'm very afraid of the fact that the tv couldn't do this for a long time gaming season,simply because of technologic factors.Everytime i think about the abl of oled and the poor hdr experience (very low peak brightness)that brings the last gaming tv(great input lag) that sony offers (sony x900h,tested by myself last days) something in my head says me that samsung cant make all of this possible without tricks,or bugs if we prefer this name ...but  this is only a personal theory...i have to focus,focus on the idea that there is people who haven't update the tv and they SAY that there is no bug like that...
I would use game motion plus  but it dims the picture like you said, i would say it doesnt dim picture as much as the bug but the difference is visible so no way,please samsung give us a simple firmware that allows game mode without any interpolation+full brightness 

[Suriya]

The problem is in PWM Flickr algorithm because when game motion plus ON the Flickr increases that is the reason it drop certain amount of brightness (for ex: led clear motion). If game motion plus OFF the PWM Flickr reduce its Flickring then the screen become brighter then the game-mode HDR bug is happening. So i think at the end if they fix this by the cost of little brightness loss which is again there is no use of buying it.

But very shame no technical team from samsung addressed this in this forum there is no reply from them only mods are replying here.

[Suriya]

if possible pls add these model numbers  with title q95t/q90t/q80t so that whoever Google the issue they can come here to join us.

Thanks