Score:1

Ubuntu 20.04.2 Screen Dims Randomly

us flag

I have tried all relevant Settings choices, including "xset s off; xset s noblank; xset -dpms; xrandr --output HDMI-1 --brightness 1.0" as ordinary user and root, but the screen still dims itself occasionally at random. How can I permanently turn OFF screen dimming?

There must be some code in the Ubuntu installation to do this!

Maybe something in /etc?

Dmitry avatar
gg flag
I've got the same on Dell G15 5515 and Ubuntu 21.10, it just dims randomly without reason
Dmitry avatar
gg flag
The problem is in ubuntu power manager upower. But you cannot uninstall it, ubuntu isn't flexible like debian. I'll try to install xcfe4-power-manager on top of it and see if would help.
Score:1
us flag

I have the same problem. I opened a bug on ubuntu's launchpad. Hoping they fix it.

Interestingly the bug stopped happening on this particular kernel version: 5.11.0-16-generic. Now it's back again.

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1938477

ldias avatar
cn flag
Welcome to Ask Ubuntu! Be sure to only post real answers to the poster's question in the Answer section.
cn flag
Even if this post doesn't provide a solution, I find it provides further valuable information.
Score:0
ar flag

As this is a perspective hasn't been discussed yet in this post, you might just have a setting that you don't want. You may have automatic brightness on, which changes the brightness depending on how bright the space around you is. In my opinion, ubuntu isn't the best at it, and it doesn't do it smoothly. This is made for laptops, so if you have a desktop, it's pointless.

You can change this in the settings app, under brightness.

John Williams avatar
us flag
That fixed it: I changer the (LG) screen brightness to 45%, Now everything seems fine.
Score:0
gb flag

Based on the Ubuntu help-page, it seems there are some settings that you can check in the Power Saving section of the Power settings.

Per official Ubuntu helppage: https://help.ubuntu.com/stable/ubuntu-help/power-whydim.html.en

If it is possible to set the brightness of your screen, it will dim when the computer is idle in order to save power. When you start using the computer again, the screen will brighten.

To stop the screen from dimming itself:

Open the Activities overview and start typing Power.

Click Power to open the panel.

Switch the Dim Screen When Inactive switch to off in the Power Saving section.
John Williams avatar
us flag
Thanks, but I've already run "Power" and tried all the displayed commands -- no matter what I do, my screen dims (including while running "power")! I need some info on HOW the various CLAIMED power-control commands control my computer.
Bish avatar
gb flag
Have you seen this answer by @vanadium ? I assume you're using the default Ubuntu with Gnome, unless you're using another desktop environment? https://askubuntu.com/a/1346130/1074455
John Williams avatar
us flag
I tried running the four screen-disablers listed there - my screen still dims uncontrollably. There is something in my OS which is wrong, but I don't know what. I suspect there is something in /etc or /var involved . . ..
John Williams avatar
us flag
I reinstalled Ubuntu (same v. 20.04.2 LTS), but the uncontrolled dimming STILL occurs. Power setting is "Blank Screen = never"; Screen Lock is "Blank Screen Delay = never", with everything else off. What controlls this screen dimming? There must be some command somewhere which can be disabled or removed!
John Williams avatar
us flag
NOTE: I have no "Dim Screen When Inactive switch" in my Power directory, which has no "Power Saving" section. Can this section be installed somehow?
Score:0
gb flag

I am using kubuntu 22 and in my case I have detected that the system set dynamic contrast option in the configuration of my additional monitor. I uncheked the option and that corrects the dim behaviour.

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