Mac Monitor Troubleshooting

September 7, 2018 11:43 AM

I have (had?) a 2009-vintage 27” Apple LED Cinema Display on my 2009 Mac Pro. It was working yesterday, but as of this morning, its screen is black. The Mac can still recognize it, and the display’s USB ports still function. The Mac’s video card still is pushing a signal to a second monitor via DVI. I’ve unplugged the Cinema Display and seen a flicker of an image for less than half a second, but that’s it. Any ideas?

I’ve confirmed it’s not just dimmed all the way (system preferences shows it up all the way—and the couple of flickers have been at full brightness). I thought it might be the backlight, but the flickers I saw would seem to contradict that. I’ve rebooted the Mac Pro a couple times.

I have an adaptor that will allow me to plug the DVI second monitor into the Mac’s Mini DisplayPort, which I haven’t tried yet, and I’ll try plugging the Cinema Display into her MacBook, but I can’t think of anything else to do.

It’s a 10-year old monitor, so it’s had a good life. But I’d love to continue to use it, as the colors are a lot better than the second display.

Thanks!

posted by Admiral Haddock to Computers & Internet (5 answers total)

First step would be to make sure that you can eliminate the cable, port and video cards as potential sources of the problem. Switch the port that you use, and the cable that you use, if possible, or test the same cable and port with a different known-good monitor, or the suspect monitor with a known-good computer/video card.

From the sound of it though, I suspect that the monitor's backlight has given out. If you're handy with electronics, this iFixit forum post looks like it might be a good place to start.
posted by Aleyn at 12:34 PM on September 7, 2018 [1 favorite]

Particularly, there's a comment in that iFixit forum post that links to the Apple Technician Guide for that display. It has a photo diagram identifying all the test points on the logic board and a detailed troubleshooting procedure for the issue you're experiencing. Some of the troubleshooting steps are similar to what you've done already, but going through them in the order given should help you identify the specific problem. Before you remove any screws you should probably check to see if the likely repair parts are available and affordable, though. I'd hate to get something taken apart only to learn I can't actually fix it.
posted by fedward at 12:53 PM on September 7, 2018

Best answer: Ugh-slash-YAY: for some unknown reason, unplugging the power cable where it connects to the monitor succeed in bringing the image back, while unplugging the power at the outlet had no effect. The power cable was fully seated at the back as normal, and the monitor had not been moved (in years), but somehow that fixed it. The computer gods work in mysterious ways.

Thanks to Aleyn and fedward for their help!
posted by Admiral Haddock at 12:59 PM on September 7, 2018 [2 favorites]

Glad it's working for you now! I'd download that technician guide anyway in case it gets memory holed at some point. Seems super useful for DIY repair.
posted by fedward at 1:02 PM on September 7, 2018

I had that exact same monitor and it suffered the exact same fate. You have have got it working for now but the issue will come back, and eventually no amount of tinkering with the cables will fix it. I never bothered taking it apart and figuring out what exactly had failed so I can't help you there, but there probably is an iFixit guide for repairing whatever it is that broke.
posted by Venadium at 2:24 PM on September 7, 2018