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ArchStudent

macrumors newbie
Original poster
Jan 31, 2020
15
1
Hello,


I am hoping someone can help with my issue and shed some light on the situation.


I have an Apple 27” LED Cinema Display MC007LL/A (non Thunderbolt model - just in case someone confuses the two) which is being problematic.


Current system setup - Mac Pro 5,1 latest bios with High Sierra, R9 280X Gigabyte Windforce with Mac EFI.


Current issues:

  1. I plug in the 27” monitor while the Mac Pro is off, and fire up the system. The monitor works, but if the screen shuts down for power saving mode it will not switch back on, just stays black. Occasionally the screen will flicker momentarily when attempting to wake it up, but still remains black.
  2. I have tried unplugging the monitor (power cord, mini display port and USB cord) and then plugging it back in, and it gets a flicker on the screen but then goes black.
  3. when the screen is working and I can see everything, I have noticed that I can not adjust the brightness level. The slider is there, but when I use it, the screen neither gets brighter nor darker.
  4. If I let the monitor sit for a day completely unplugged and then plug it in the screen comes back on and works (except for the brightness control).

I can confirm there is zero issues with the Mac Pro as I also have a an Apple 24” LED Cinema Display. When I swap the two and plug in just the 24” monitor, I have zero issues with the 24” monitor.


Hypothesis 1: the I/O cable on the 27” monitor is failing or has failed since I am unable to adjust the brightness level (and yes, the USB cable is plugged in as well).


Hypothesis 2: the I/O cable and monitor’s internal power board are both faulty based on results.


Has anyone else had a similar issue or read of an issue similar to the issue(s) I am having.


Thanks for any and all help!
 
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