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

[Alekkk]

This is a known fix for R series, but won’t work for T series as the advanced submenu unlock code has changed. Note that if you do this on your R, setting values to 100 will disable dimming entirely, better to try lower values to keep some dimming when screen is mostly dark and needs it because Samsung’s local dimming isn’t good enough. Samsung will probably also remove these posts for violating terms blah blah. If anyone has or can find out the new code, though, would love to know.

[Alekkk]

Oh hey! The new code was posted by someone in the comments of that video @RiotRMD posted! Thank God! 🎉 https://www.youtube.com/watch?v=hGCxvYBJoek 🎉

Just verified it works. This is not a real solution, don't use this unless you know what you are doing. Samsung need to fix this properly. But if you read up on what PWM values do and how they work with Samsung sets, this can fix the dimming.

[jdk2087]

So wait, is this a fix for it or not? The instructions seem pretty simple in the YouTube video. I don’t see myself messing it up at all. Would this technically be a complete fix for all the issues I’m having that should technically be firmware fixed by Samsung? If so then I’d rather for now do this so that I don’t have a gimped TV. 

[jayh89]

Accessing the service menu can invalidate the warranty... at least I’ve heard of it happening. I’m not over keen on doing this. 

[Iskandarkebab]

I've read that this fix may also kill blacks as TV no longer dims at dark scenes. This fix is nothing but putting backlight to Max. 

Besides that, modifying this affects all sources, not only games.

[LCDeez]

Yep, it’s not a fix at all in my book. In fact, there is no fix as of yet, needs a software patch to deal with this. If you void your warranty messing with the service menu and another issue pops up, you’re sol and they could easily not fix your panel or replace the TV. 

[Iskandarkebab]

Dont think theres gonna be such patch. People with last year models have similar issue and its still unsolved. Play with motion plus on, optimize your HDR on your PS4 and enjoy... Oh, and put black equalizer to zero, It definitively kills blacks and dark colors. If you setup TV to high local dimming, low contrast enhancer and no black equalizer, when setting up HDR on PS4 It covers all the spectre of dark and bright colors.

[Suriya]

Definitely I'm not going to try this. Looks Scary pwm values related to number of zones and nits of brigthness. Without knowing proper value anything could happen to the TV

[Alekkk]

Best general advice is: don't use the service menu. If you don't understand how dimming works or what PWM is, don't even think about it. If you don't have good consumer protection laws in your country or are worried about your warranty, don't do it. 2020 models are also different to 2019 models, so you can't just blindly follow whatever instructions you find. Don't use the service menu.

If you know what you're doing, however, it's possible to tweak the PWM Mid value to alter the perceptible dimming threshold. The default value is 5 and setting it to 100 disables global dimming entirely, which is a lot of variability; it's not just kill black levels or live with dimming. But again, if you're even remotely unsure about it, don't do it.

This is not a real fix, I just wanted to let people know it's possible. Keep harassing Samsung for a proper fix that everyone will benefit from.

[Suriya]

Guys pls everyone do call samsung toll free number daily and tell them connect with their manager he only push everything overseas.

I did the same and yesterday 4 technician from samsung came and installed beta version of upcoming updates from usb and checked it but it is still happening no fix on the next update itself which is not online then from the service menu enabled the debugger and logged everything on USB drive.

Today i called again and spoke with the regional technical manager he said there is no information regarding this dimming bug on the debugger log file and everything informed overseas they never responded to him. 

Clearly visible that samsung didn't fix the dimming issue on the upcoming update for the T series.

And they are being silent on this issue as per the information given by the regional technical head

But guys pls everyone call service toll free number and fight with your regional manager they only able to push this forward. Or ask refund from samsung not from the shop you bought