[GH-ISSUE #1001] Apple Cinema Display immediately too dark #604

New issue

Closed

opened 2026-05-05 06:21:36 -06:00 by gitea-mirror · 3 comments

gitea-mirror commented

2026-05-05 06:21:36 -06:00

Owner

Originally created by @thedesignerdave on GitHub (Apr 12, 2022).
Original GitHub issue: https://github.com/MonitorControl/MonitorControl/issues/1001

Before opening the issue, have you...?

Searched for existing issues
Read through the Monitor-Troubleshooting Wiki
Updated MonitorControl to the latest version (if applicable)

Describe the issue

I installed monitor control on my Macbook pro to control the brightness of an external monitor. After instillation, I adjusted the brightness slider in the app. The second I touched the slider, my monitor when to about 40% brightness even though the slider bar shows that it's at full brightness. I've tried disconnecting, reseting v/pram on my mac. Removing and reinstalling monitor control and the monitor is stuck. I've even hooked it up to a different macboook pro that doesn't have Monitor control and it's still dark.
Please save me from the darkside!

Expected behavior

I expect the software to be able to adjust the brightness to 100%

Anything else?

No response

Environment Information (please complete the following information)

- macOS version: BigSur 11.6.5
- Mac model:Macboook pro 15 inch 2017
- MonitorControl version:?
- Monitor(s): Apple cinema 27 thunderbolt display
- Monitor Cable(s)/Connection(s):Thunderbolt to usbc adapter
- Apple Silicon/M1 (yes or no):?

Originally created by @thedesignerdave on GitHub (Apr 12, 2022). Original GitHub issue: https://github.com/MonitorControl/MonitorControl/issues/1001 ### Before opening the issue, have you...? - [X] Searched for existing issues - [X] Read through [the Monitor-Troubleshooting Wiki](https://github.com/MonitorControl/MonitorControl/wiki/Monitor-Troubleshooting) - [X] Updated MonitorControl to the latest version (if applicable) ### Describe the issue I installed monitor control on my Macbook pro to control the brightness of an external monitor. After instillation, I adjusted the brightness slider in the app. The second I touched the slider, my monitor when to about 40% brightness even though the slider bar shows that it's at full brightness. I've tried disconnecting, reseting v/pram on my mac. Removing and reinstalling monitor control and the monitor is stuck. I've even hooked it up to a different macboook pro that doesn't have Monitor control and it's still dark. Please save me from the darkside! ### Expected behavior I expect the software to be able to adjust the brightness to 100% ### Anything else? _No response_ ### Environment Information (please complete the following information) ```markdown - macOS version: BigSur 11.6.5 - Mac model:Macboook pro 15 inch 2017 - MonitorControl version:? - Monitor(s): Apple cinema 27 thunderbolt display - Monitor Cable(s)/Connection(s):Thunderbolt to usbc adapter - Apple Silicon/M1 (yes or no):? ```

gitea-mirror closed this issue

2026-05-05 06:21:38 -06:00

gitea-mirror commented

2026-05-05 06:21:42 -06:00

Author

Owner

@waydabber commented on GitHub (Apr 12, 2022):

Hi there,

try setting this to 255, that tends to help with older Apple displays which (in an undocumented way) support DDC commands for brightness control:

@waydabber commented on GitHub (Apr 12, 2022): Hi there, try setting this to 255, that tends to help with older Apple displays which (in an undocumented way) support DDC commands for brightness control: <img width="842" alt="Screen Shot 2022-04-12 at 17 24 02" src="https://user-images.githubusercontent.com/37590873/162997507-b1bbed4f-d8e0-49c4-8a69-0d16675ee49f.png">

gitea-mirror commented

2026-05-05 06:21:44 -06:00

Author

Owner

@thedesignerdave commented on GitHub (Apr 12, 2022):

Hi there,

try setting this to 255, that tends to help with older Apple displays which (in an undocumented way) support DDC commands for brightness control:

Thanks for the suggestion but it didn't work.

@thedesignerdave commented on GitHub (Apr 12, 2022): > Hi there, > > try setting this to 255, that tends to help with older Apple displays which (in an undocumented way) support DDC commands for brightness control: > > <img alt="Screen Shot 2022-04-12 at 17 24 02" width="842" src="https://user-images.githubusercontent.com/37590873/162997507-b1bbed4f-d8e0-49c4-8a69-0d16675ee49f.png"> Thanks for the suggestion but it didn't work.

gitea-mirror commented

2026-05-05 06:21:47 -06:00

Author

Owner

@waydabber commented on GitHub (Apr 12, 2022):

Well, connecting the display to a Mac that has an OS from before Apple just removed brightness control support supposedly fixes the issue. The problem is that these displays respond to DDC commands to some extent and depending on firmware and hardware revision they work or they just do this. Others reported that using Lunar by @alin23 did fix the problem (maybe because it uses different timings somewhat or repeats DDC commands more or differently - who knows). The problem is surely fixable and probably by tuning DDC commands things would work but I don't have a display like this to experiment.

for more info see these:

https://github.com/MonitorControl/MonitorControl/discussions/970
https://github.com/MonitorControl/MonitorControl/discussions/739

@waydabber commented on GitHub (Apr 12, 2022): Well, connecting the display to a Mac that has an OS from before Apple just removed brightness control support supposedly fixes the issue. The problem is that these displays respond to DDC commands to some extent and depending on firmware and hardware revision they work or they just do this. Others reported that using Lunar by @alin23 did fix the problem (maybe because it uses different timings somewhat or repeats DDC commands more or differently - who knows). The problem is surely fixable and probably by tuning DDC commands things would work but I don't have a display like this to experiment. for more info see these: https://github.com/MonitorControl/MonitorControl/discussions/970 https://github.com/MonitorControl/MonitorControl/discussions/739