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[GH-ISSUE #705] Apple Thunderbolt display stays dark #468
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Reference: github-starred/MonitorControl#468
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Originally created by @Dynynaxerny on GitHub (Oct 11, 2021).
Original GitHub issue: https://github.com/MonitorControl/MonitorControl/issues/705
Originally assigned to: @waydabber on GitHub.
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Question
Hello! Do any of you have any advice? I installed MonitorControl and after a few tests my 27 inch Apple Thunderbolt display suddenly went very dark. All attempts to reverse this are unsuccessful. I can only darken further. The Apple Thunderbolt Display is connected to a 2018 MacBook Pro together with Apple LED Cinema Display. The Apple LED Cinema Display behaves as before.
@waydabber commented on GitHub (Oct 11, 2021):
Hi, which app version are you using? Are you using v4.0.0-beta2, or 3.1.1? If the latter, can you please try the former as it should handle Apple displays better. Thank you!
@waydabber commented on GitHub (Oct 11, 2021):
Hey @Dynynaxerny - any update on this? Were you able to resolve the issue or does it still persist? Apple Thunderbolt displays are controlled via USB using Apple's own DisplayServices protocol. The previous MonitorControl releases however treated them as ordinary external displays, trying to send DDC commands to these displays. According to reports, some of these displays do respond to these commands - maybe this caused the issue. Version 4.0.0 should work better in this regard. But this is just a theory on what might have caused the issue, as it might be something completely different.
Please let me know if I can be of any help. Until that time I'll close this issue (but feel free to respond anyway)! Thank you!
@Dynynaxerny commented on GitHub (Oct 11, 2021):
Hello! Sorry for forgetting something as important as the version number! I am using version 4.0.0 Build 6443 Intel.
The Apple Thunderbolt display doesn't have its own USB input, the monitor is only connected via Thunderbolt, right?
cable
• Integrated Thunderbolt cable
• Integrated universal MagSafe cable (up to 85 W)
Peripheral connections
• Three active USB 2.0 ports
• FireWire 800 connection
• Gigabit Ethernet connection
• Thunderbolt connection
• Connection for Kensington anti-theft device
Today I connected this monitor to a MacBook Pro 2015 and it is VERY dark there too, could it be broken by MonitorControl?
Is there any way to reset the monitor?
@Dynynaxerny commented on GitHub (Oct 11, 2021):
I forgot! Thank you for your help!
@waydabber commented on GitHub (Oct 11, 2021):
I meant Apple's protocol to control the display is using MCCS over USB I think, not DDC - but yes, the data communication is embedded in the Thunderbolt link. But if you used v4.0.0 then it should not have sent a DDC command to it so my theory was wrong then.
I am not sure if the display was broken by MonitorControl (or if it was, I don't know how, since we use Apple's own service to talk to the display). It might a backlight issue which manifested itself with a bad timing.
I don't think there is a way to reset the Thunderbolt display except for unplugging it for a while.
Strangely, this issue seems to be common enough (as 89 ppl flagged this):
https://discussions.apple.com/thread/7610153
Also:
https://discussions.apple.com/thread/6791830
https://forums.macrumors.com/threads/very-dim-thunderbolt-display.1606459/
@waydabber commented on GitHub (Oct 11, 2021):
An other thing I can think of is if the backlight was failing or about to fail, maybe if the brightness control was tested a bit too vigorously, it could push it over the edge. But I am not sure honestly. I am sorry that you have to deal with this.
If you want I can convert this issue into a discussion, maybe other Thunderbolt Display owners have some tips or feedbacks whether they experienced anything like this.
@Dynynaxerny commented on GitHub (Oct 12, 2021):
hi, I'll have a look at it again this weekend and I'll report back. to me it also looks like the background lights are off. I disconnected the screen once maybe that helps, I'll report. I can't use him like that anyway.
@waydabber commented on GitHub (Oct 12, 2021):
Hi. Well, if background lights are completely off, then it is most probably the issue described in the forums. This seems to be a common problem for Thunderbolt displays which apparently exhibits itself with age. Hopefully it is something that can be remedied by one of the proposed fixes in the forums but if it is a permanent hardware issue (the LEDs or backlight control panel failed) then you'll need to have it serviced I am afraid.
@T-rot commented on GitHub (Oct 29, 2021):
Hi there, I m having the same issue. I have two LED 27 inch Apple Thunderbolt displays connected to my MacBook Pro (16-inch, 2019). Both displays were working fine until i opened the Monitor Control app. At this point both screens dimmed to what I would say is about 50% brightness of what they are capable. In the Monitor Control settings it says both screens are set to 100% but they are definitely much much dimmer.
I have tried deleting the app to see if the screens would default back to the brightness/settings that they were displaying at before but no luck. I have also tried to re-install the apple firmware 1.2 update for these displays with no luck.
Any help with this would be much appreciated as it is very hard to work on these screen now.
Thanks T
@waydabber commented on GitHub (Oct 29, 2021):
Hi, were you using v4.0.0 or a previous version of the app?
If you were using v4.0.0 then can you please send me what you see in the Displays tab for each displays? Please enable
Show advanced settingsas well. If the Control Method isHardware (DDC)then can you please change theBirghtness/DDC maxvalue to something higher than 100 (200 or 250) and see if you can increase the brightness further?If you used a previous version of the app or the advanced section is disabled and you see
Hardware (Apple)then the instructions don't apply and we will have to try something else.Please let me know if this helps.
@T-rot commented on GitHub (Oct 29, 2021):
Hi there, I just set the screens back up and have tried the "Use hardware DDC control" and changes the DDC max output and that seems to have fixed it. Oh and yes i was on 4.0.0 Thanks so much for your help :)
@waydabber commented on GitHub (Oct 29, 2021):
Hi, I am glad that fixed it. What is strange is that an Apple Thunderbolt Display should not actually be controlled via DDC (as it has a rather buggy implementation) but should use Apple's CoreDisplay protocol which communicates through the USB lane of Thunderbolt 3 and MonitorControl should properly detect that.
Can you double check if you are not using a 27" LED Cinema Display instead? The 27" LED Cinema and Thunderbolt displays look almost the same, the difference is in the connector (one has a mini display port connector along with some other connectors, the other has a Thunderbolt 2 connector which looks exactly like a mini displayport connector).
Also can you make a screenshot of the Graphics/Displays under Hardware in System Report (found under About this Mac in the Apple menu)?
Thank you!
@Dynynaxerny commented on GitHub (Oct 31, 2021):
Hello!
I use MonitorControl Version 4.0.0 Build 6851, have a MacBook Pro (15-inch, 2018), 2.9 GHz 6-Core Intel Core i9, 32 GB 2400 MHz DDR4 and with a Radeon Pro Vega 20 4 GB with macOS Monterey 12.0.1.
The Thunderbolt display is connected to another LED cinema display (27 inches), an old EIZO EV2333W and the internal 15-inch display on the above-mentioned MacBook Pro. Except for the Thunderbolt display, everything works without any problems. I've tried everything possible, but to no avail, the Thunderbolt display remains dark!
However, I tried a tip and held a flashlight in front of the monitor camera and lo and behold, the brightness was immediately there. Apparently the calibration of the automatic brightness adjustment has been lost. I don't know where to turn it off either. Does that help you? Greetings Andreas
@waydabber commented on GitHub (Oct 31, 2021):
I think the ambient led sensor can be turned off in Displays Preferences. If the sensor has failed (for example always reports darkness) and is not turned off, the display will tend to tune down brightness all the time which is rather annoying.
If you can't control the LED cinema display (but you should via USB) and turn it off then I don't know any other method to fix this, except maybe sticking a small led strip in front of the sensor and crank it up. :)
@waydabber commented on GitHub (Oct 31, 2021):
(btw the light sensor is located next to the camera, so you should not direct the led to the camera but the sensor)