- Joined
- Oct 16, 2010
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- Your Mac's Specs
- 2011 27" iMac, 1TB(partitioned) SSD, 20GB, OS X 10.11.6 El Capitan
Rod, both times it has happened the bar graph for the brightness has been hard over to the left.
I wonder if the same problem could be related to this and their fix:
Second, after shutting down the system for an hour or so, it came back on fine for about 15-20 minutes, then the screen started doing its dimming again. Got me thinking it might be a thermal problem somewhere. Well, a little more searching on the internet turned up some cases where the display did funny things when the system got hot ... and there were specific references to checking the ventilation holes on the bottom of the iMac as well as the vent strip on the top. Lo and behold, there was an awful lot of dust clogging over half of the vent holes on my iMac! So I vacuumed everything out, clean as a whistle.
...
Who would have thought dust in the vents would have caused this? I'm glad it seems to have been that simple a fix.
It seems the dust in the vents was causing the iMac to overheat which in-tern lowered the brightness of the display...
Or maybe just a thorough dusting internally might be needed...
iMac screen dims by itself (not set to au… - Apple Community
discussions.apple.com
Maybe worth having a look inside???
- Patrick
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