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Apple Desktops Discussion of Apple's desktop machines including Mac Pro, iMac, Power Mac, and mini

iMac Flickering Screen


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galaxy7

 
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I have a 21.5" iMac and the screen brightness flickers! It has posed zero problems on using the computer; everything works just fine and completely normal. The screen doesn't change colors nor does it go completely blank or anything like that. It's almost as if some auto-brightness display feature is freaking out and constantly trying to adjust. It adjusts the brightness completely on its own and completely random. Any thoughts?

It doesn't seem to be creating any types of problems with the display; just really annoying!
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harryb2448

 
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Any chance the iMac is still under AppleCare warranty?

Sounds like it MAY be a backlight problem. You would need to get it diagnosed and perhaps if not under warranty have a go at it yourself, depending on the precise model:-

Intel iMac 21.5" LED Backlight Board

Hang on to those original install discs like grim death! Using OS X.7 or later make a bootable USB thumb drive before running Installer!
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MYmacROX

 
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I assume you've already looked at the auto-brightness settings and turned that feature off.

Do you have Apple Care for your iMac, or is it still under the 12 month warranty period?

16GB iPhone 5, 64GB Wi-Fi only iPad 1st Gen.

Reminder: Please include your Mac's specs. This will make it much easier for the other members to assist you.
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galaxy7

 
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No warranty...she's a few years old. May have to live with it.

I'll try turning off the auto adjust...where's that at? Found the brightness, but not the auto??
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harryb2448

 
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Depending on your operating system found in System Preferences > Displays > Display and a selected box under Brightness. Good luck.

Hang on to those original install discs like grim death! Using OS X.7 or later make a bootable USB thumb drive before running Installer!
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chscag

 
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In addition to the advice received from Harry, also try resetting the System Management Controller. You do that by shutting down your iMac, unplugging it from the AC socket, let it set for about 15 minutes, plug it back in and reboot.
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galaxy7

 
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Quote:
Originally Posted by harryb2448 View Post
Depending on your operating system found in System Preferences > Displays > Display and a selected box under Brightness. Good luck.
I don't have a box under the brightness slide bar...interesting!
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harryb2448

 
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Hard to suggest further you have not supplied operating system details alas.

System Preferences do differ between OS X.6, X.7, X.8 and X.9.

Hang on to those original install discs like grim death! Using OS X.7 or later make a bootable USB thumb drive before running Installer!
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galaxy7

 
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OS X 10.9.1. with Mavericks installed. Problem was occurring before Mavericks though.
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harryb2448

 
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Well rather than a box maybe I should have said a tickable radio button. Make sure it is not selected.

Hang on to those original install discs like grim death! Using OS X.7 or later make a bootable USB thumb drive before running Installer!
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galaxy7

 
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No box underneath the brightness slide bar!
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