⟐ Commented January 13, 2022 at 13:55 MST

After connecting the display to my Macbook Pro and turning it on, it never fails to dim after several minutes of use. None of my other displays have this issue, and it does this with any computer I hook it up to. I primarily use my displays together, daisy-chained, but the problem occurs even if I just have the one malfunctioning monitor connected directly to my MBP.

I’m pretty sure that even when it first turns on, it isn’t at full brightness (I’ve used one of my other TB displays as reference), but it’s pretty close. Eventually (after 1-6 minutes), it dims, dropping down to around 65-70% brightness. Using the brightness control in System Preferences lets me turn down the brightness but even with the slider at the fullest setting the most I get is that 65-70%. If I unplug the TBolt and power cables, wait a bit, then plug them back in, SOMETIMES I can get it to work again. But most of the time it needs to be off for several hours before it goes back to “normal”.

And finally, it’s started to shut off after using it in the dimmed state for more than about 20 minutes. I can’t tell if it’s just the backlight or if the entire device is shutting down, but I’ll check next time it does this and update. Once it started this behavior a few months back, I stopped using it altogether. But now I’m back banging my head against the wall trying to get it functioning properly.

Here is what I have tried so far…

1. Firmware is up to date (all my monitors are 26.2 firmware, 2.0.7 port micro)
2. “Automatically adjust brightness” is turned off on all screens
3. Thunderbolt/Magsafe cable replaced
4. Power cable replaced
5. Logic Board replaced
6. Power Supply replaced
7. I’m fairly confident that the ambient light sensor is not being obstructed

All of these repairs went very smoothly, and I’m quite familiar with the internal topology of the TB Displays now. I’ve been repairing electronics and building my own computers for two decades now, so I’m fairly certain I didn’t mess anything else up during th repairs. Nevertheless, my exact same problem persists, seemingly no worse or better.

Below is a photo of my last two displays—broken one on the left, normal one on the right. It’s very hard to take an accurate picture, but I’ll say that the disparity in brightness between the two monitors is WAY more noticeable in person.

Also including a screenshot of TBolt system report in case that’s helpful:

I have a new LCD panel coming in next week, but I just don’t feel like that’s going to help. And it’s the last idea I have as to what could be replaced to fix my problem. So, I’m hoping maybe someone here will have a suggestion or something else I can try.

Any advice would be very much appreciated!

==============================================

UPDATE 08/23/2020: The monitor went out during tests again today, and I was able to confirm that it is the backlight that is shutting off when it goes dark. If I shine a powerful light into the screen I can still see the OS on it. Should be receiving the new LCD panel today, and I’ll update again once that’s installed.

⟐ Edited by author August 23, 2020 at 14:56 MST

After a few minutes (time depends, keep reading), the display will give image and the laptops will detect it as normal, and then I can work on it.

How much time it takes to give image, depends for how long has been the display connected to the outlet. If It has been connected for a while (like 12 hours or something), then I get image after 10-15 minutes.

If I have not connected the display to the outlet for more than 12 hours, then it will take 45 to 60 minutes to give image.

The display’s cable to the laptop used to be frayed, and every time you touched it, the display would lose image. I ordered a new cable and replaced it, and that fixed the cable issue, but the image delay is still there.

I also ordered a new logic board, and replaced it, but that didn’t fix the problem.

Have any of you had an issue like this one, and can direct me to a proper thread on how to tackle it? Or does anyone has any idea what could be?

⟐ Edited by author June 08, 2020 at 13:30 MST

It’s not possible to get it, are there any alternatives e.g. from iMac 27 inch 2011 (593-1352 )?

Thanks.

⟐ Reopened April 13, 2020 at 7:33 MST

The A1407 fails to generate an image. Haven’t tried with other Apple computers, yet. Also have yet to shine a light on the A1407 to see if there is actually an image, but no backlighting.

What else can I test and try?

⟐ Commented July 10, 2019 at 4:23 MST

It’s not recognized by MacBook Pro at all, it doesn’t show up as a secondary display.

When I plug in my Cinema Display the fan inside spins for a second and whirrs and then stops.

Could it be my Logic Board has finally gone out?

—————

You can also hear the fan spinning when my MacBook is plugged in, but I still have no visuals, display options, or usb hub.

⟐ Commented December 04, 2018 at 20:38 MST

I got this 27” Thunderbolt Display for less than $50 with no backlight.

The LCD is up and running with the flashlight test but here is the interesting part that makes this one unique: I don’t get any backlight upon connecting the thunderbolt cable, not even a flash.

Is it possible that this is still the same issue that is fixed by bridging some 3.3v connection on the LED driver IC?

I can use the speakers, ethernet, and webcam, so it’s not an issue with the cable and there is no visible damage to the logic board.

I am looking for a quick list of things to check, thanks for any and all comments!

Timothy

⟐ Commented September 25, 2018 at 18:21 MST

I've replaced the frayed All-in-one cable (AIO), and it send power to my Mac (Air Mid-11), however it refuses to recognise that a display is connected via the thunderbolt cable.

Can I troubleshoot this somehow?

Regards,

Stephan

⟐ Commented June 07, 2018 at 17:58 MST

I replaced the power supply for the same buzzz noise issue from an ASP. After 5 days of using same issue again.

please help me for the same, I will be killed by my boss if the issue is not resolved urgently.

Please please please

⟐ Edited December 22, 2016 at 21:07 MST

Here is what I see:

These days the unit has to be unplugged for a while to even turn on. After it goes black everything else is still working. After about 20 minutes of being on this perfect looking screen goes black on me. The Mac thinks the display is still there. USB is still working. Speakers and all is OK. Firmware is all up-to-date.

I had it checked at the Apple store and they say it's the display unit. ($840)

I'm thinking of open the thing up and go at it with cooling spray (maybe it's "just" a cold solder...) What have I to lose? Anybody there with a better idea?

I checked 24.5V - it's in normal range (24.8 - 25.05V). USB, camera, sound still working properly. Picture has no visual issues and artefacts (as much as possible to see with 10Hz and 1% lightness backlight).

I have confirmed 230V going into the board; nothing coming out of the cable that would feed into the MacBook magsafe adaptor; not sure what to test for on the main 12 pin connector going to the logic board. Should the magsafe connector charge a MacBook if the logic board doesn't work?

⟐ Edited by author March 15, 2016 at 21:44 MST

Power turned off - unit cold - all works again....

What could that be?

Can anyone confirm or not that this is possible?

⟐ Reopened October 12, 2015 at 11:02 MST