So I have a 27" Thunderbolt in my office that somebody else used to use. Now it is considered "broken", but I think it can be made to work. Here's a rundown of its current state:

I can connect it to my MacBook Pro, and the computer recognizes the display. It shows up on the "Arrangement" tab. It has working USB ports when I connect its USB cable. Even its speakers work. But the display is completely black, doesn't even turn on or flash.

What do you think can be done to fix it?

Thank you.

  • not sure if this is helpful but see here
    – Honey
    Mar 2, 2017 at 4:28

7 Answers 7


I have had a similar issue a few weeks ago. In my case the screen was not "completely" black, but it was close. Going to the "Display" tab in the settings app and turning up the brightness did the trick.

However, it may also be an actual hardware failure if there is nothing at all visible on the screen. In that case you should take the display to an Authorized Apple Service center.

In the pulldown, select Mac repair since these require the same training, tools and skill to repair as an iMac does.

  • There is only 1 brightness setting in the Displays tab, and that changes the brightness of the MacBook screen. Is there another setting that I can access that refers to Thunderbolt?
    – cartonn
    Sep 25, 2013 at 20:28
  • At least in my case the brightness setting in the Displays tab also turned up the brightness of the Thunderbolt screen. In that situation the slider was at the lowest possible setting and the Thunderbolt display was almost (but not entirely) black. I am away from my office now so I cannot confirm whether it always works this way, but at least in that situation it was the display brightness of the Thunderbolt not the MacBook screen that was affected.
    – user8472
    Sep 26, 2013 at 5:38

My Thunderbolt cable was recently diagnosed as the cause of a 'dark' display. Like you, I have basic secondary features -- such as the Thunderbolt display bridging my MacBook pro over to the LAN. So consider a) getting a new cable; b) wiping any dirt accumulation in the cable or interface.

  • 3
    But how would I use a new cable? The cable is attached to the back of the monitor. As far as I can tell, I can't simply unplug it.
    – cartonn
    Sep 25, 2013 at 14:47
  • You open the display and replace the cable.
    – vy32
    Jun 21, 2015 at 12:49
  • @vy32 you mean buying a new thunderbolt to thunderbolt cable and attaching that the visible ports of the thunderbolt display and my macbook?
    – Honey
    Mar 2, 2017 at 1:55
  • That works. Or you can open up the monitor. The cable that goes into the monitor plugs in.
    – vy32
    Mar 3, 2017 at 2:13

I had this issue. For me the fix was to leave the display unplugged from the power for a few minutes. It came back to life after that. I did also blow into the cable in case there was dust inside. The PRAM reset had no effect


In case somebody is here with the same issue I had...

I had a brand new 27" Thunderbolt display, it replaced my previous one. Came out of box DOA. No power, no show in "display" settings. Tried on Mac Mini, and MacPro (late 2013). Tried the Command+Option+P+R key combo and did the reset there, but it did not work. Tried unpower for 30 minutes, many many attempts....

Just about to give up and rebox for another trip to a service center. Then I found a list of startup shortcut keys. One of the ones on the list was just pressing the "D" key during boot up. I did a shutdown, put back on the Thunderbolt display (was using an old HDMI screen to run the mac temporily) booted MacPro once the 'start up ding happened' I hit the D key and held it. Seconds later 'BAM!' I got the screen showing me a shutdown/restart and a login screen (slightly different from normal, but similar to login), after reboot its back up and going again. Hope this stays that way.

Hopefully someone who has a similar issue can get going this way too.


Black screen issue resolved... I purchased a fully working and tested used Thunderbolt monitor yesterday. Everything worked fine at the store when tested on a MBP that is identical to my own.

At home, the screen would not come to life and remained black even though it was available in System Preferences. I could also mouse over to the black screen. So clearly it was recognized, just no display.

After trying a new Thunderbolt cable, resetting PRAM, restarting my MBP multiple times and unplugging and plugging in the Tbolt cable (original and the new one) with no luck, I plugged the power directly into the wall. The screen flickered a bit so I knew I was onto something. A few more times switching between wall power and surge protector and the display finally came to life. I have the Thunderbolt plugged directly into the wall now which is not ideal, but hey - at least it works.

So, not exactly steps you can follow directly, but it does prove that these monitors are glitchy but can be resurrected. Frustrating! At least I'm in business now and I hope you're as lucky.


You could use a Thunderbolt cable to connect to the display Thunderbolt port. That should let you know if it's a cable issue or a display issue.

  • Unfair to vote this down. These displays have a cable that cannot be removed, so testing another cable is a perfectly viable diagnostic. Aug 17, 2016 at 9:07

I had this issue and tried all of the suggestions here, and on many other threads. Reset SMC, PRAM, tried different computer, cable, brightness settings, etc. I also tried unplugging it and leaving it for a few minutes. Nothing I did would wake the display up. The display was detected: I could hear music through the speakers; I could see the preferences and adjust them; the only issue was that it was not showing the video signal. Last night I had given up and started looking for a new display, a Dell or something. So I unplugged my Thunderbolt display and went to bed.

This morning, I plugged it back in and tried again - it came to life immediately! Inexplicably.

So, I have arrived at the conclusion that the inherent problem with these displays is related to temperature. It's hot here at the moment, and my office is not air conditioned. The back of the display is also pointing out of the window at the morning sun. These displays have fans inside, so need to be running as cool as possible; I think they need to be turned off completely now and again, and cooled down sufficiently.

Hope this helps someone. Please comment if this also fixed your 'dark screen' problem.

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