Author Topic: Why did my computer screen do this?  (Read 383 times)

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Offline daniel1948

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Why did my computer screen do this?
« on: March 31, 2019, 12:01:58 PM »
I got back to Spokane (not "home" as Maui is home now) yesterday. I turned on the computer after five months of being off. For a little while everything was fine, and then the screen went black, which is what normally happens if I give it no input for 15 minutes or so, or if I move the cursor into the bottom left corner. I moved the cursor around a but, and then the screen came back on, but then after a bit it started to flicker and went black again. During one of the black periods I continued to type, and when the screen came back on, everything I had typed was there. So the computer was still working. Moving the cursor around, and randomly hitting keys at first seemed to bring the screen back on, but then later it didn't, so I don't know if that was actually doing anything.

I shut off the computer and re-started it a couple of times and the same thing happened. I phoned Apple, who were able to look up when I bought the computer, which was about 3 1/2 years ago, so it's out of warranty. They also told me that the "Genius Bar" at the Apple store does not charge for diagnostic work. So they won't charge me to give me a repair cost estimate.

I tried shutting it off and turning it on again, for about the third or fourth time, yesterday afternoon, and since then it has been working without any problems.

Late 2015 iMac, Retina 4K 21.5-inch screen, Intel Iris Pro Graphics 6200 1536 MB. Apple Bluetooth trackpad, batteries were low but it stopped misbehaving even before I put freshly-charged batteries in. Wireless Logitech keyboard. OS X El Capitan version 10.11.6.

Any ideas what caused this, or whether it's a warning signal? If it's a serious problem and expensive to fix, I could dump the computer and get something new when I get back to Maui. If it was just a one-time glitch I plan on shipping the computer, which has to be cheaper than buying a new one there. I've been getting by with just the tablet for 5 months, but it's kind of annoying sometimes and I do want a full computer.
Daniel
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"Anyone who has ever looked into the glazed eyes of a soldier dying on the battlefield will think long and hard before starting a war."
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Online CarbShark

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Re: Why did my computer screen do this?
« Reply #1 on: March 31, 2019, 12:16:53 PM »
Restart in safe mode. Hold down the shift key until the apple logo come up. After it starts let it run for at least ten minutes. You can use it in safe mode but you may notice display issues and some things may seem slow.

Restart normally and see what happens.





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Online CarbShark

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Re: Why did my computer screen do this?
« Reply #2 on: March 31, 2019, 12:18:55 PM »
( I would do that now, and again if the problem comes back.)

Did you notice if the clock and calendar were off when you first started?


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and Donald Trump is President of the United States.

I'm not a doctor, I'm just someone who has done a ton of research into diet and nutrition.

Offline daniel1948

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Re: Why did my computer screen do this?
« Reply #3 on: March 31, 2019, 03:26:45 PM »
If I re-start in safe mode, what am I looking for? Just to answer the question if the problem happens or not? And since it is working fine now, what do I look for if I re-start in safe mode?

The clock and calendar are correct. I can't say for sure if they were right before, but I think they were.
Daniel
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"Anyone who has ever looked into the glazed eyes of a soldier dying on the battlefield will think long and hard before starting a war."
-- Otto von Bismarck

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Re: Why did my computer screen do this?
« Reply #4 on: April 01, 2019, 01:57:40 PM »
If I re-start in safe mode, what am I looking for? Just to answer the question if the problem happens or not? And since it is working fine now, what do I look for if I re-start in safe mode?

The clock and calendar are correct. I can't say for sure if they were right before, but I think they were.

Restarting in safe mode launches with minimal system extensions and resets a number of caches and stored values. What you're looking for, in your case, is no issues the next time you start when it's not in safe mode.

There are 1 or two batteries that the mac relies on to maintain things like the clock. If you haven't started in weeks/months it's very possible the battery has discharged and that can cause issues. The clock/calendar can be a good indicator of that issue but if your mac is set to update automatically, they can reset before you notice they're off.
and Donald Trump is President of the United States.

I'm not a doctor, I'm just someone who has done a ton of research into diet and nutrition.

Offline daniel1948

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Re: Why did my computer screen do this?
« Reply #5 on: April 01, 2019, 03:15:48 PM »
Thanks for all that. The problem still has not reappeared, so I am provisionally putting it down to a passing glitch, and if it doesn't reoccur I'm going to forget about it. Pretty soon I'll be shipping it to Maui, and I'll wait and see if it survives the trip.
Daniel
----------------
"Anyone who has ever looked into the glazed eyes of a soldier dying on the battlefield will think long and hard before starting a war."
-- Otto von Bismarck

 

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