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YanniDepp

macrumors 6502a
Original poster
Dec 10, 2008
556
132
Hello,

I've just noticed some really weird dark patches in both lower corners of my 4K iMac (late 2015). I don't normally have anything open full-screen - I normally scatter small windows across the screen - so I can't say whether these have suddenly appeared or if they've slowly appeared over time.

I've never seen anything like this before. If I move any content over it (text, graphics etc), it looks like the dark patches are a few millimetres behind the display. It's like there's some sort of dust or smoke between the backlight and the LCD.

I'll be honest - if I saw something like this on somebody's phone, I'd assume it was liquid damage or pressure. But this is an iMac that's been sitting on my desk for 18 months with no liquid or smoke anywhere nearby. It's not like there's any air-holes in the back that could've sucked in dust at those corners.

I've got it booked into the Apple Store on Saturday, and I've got the 3 year educational warranty, so it should be fixable. But it's really weird. Has anyone seen anything like this?

imac-bottom-left.jpg

imac-bottom-right.jpg
 
I bought an iMac with the same problem off eBay. I had to get a credit from the seller. Apple will charge you about 550 to fix (but you're under warranty so that's good).

It's basically dust that blew into the screen thru the bottom corners. Shouldn't be possible, but apparently it is. The lcd is not airtight. Only thing I can think of is that you live in a humid/slightly dusty environment and that was enough to build up a problem over time.
 
I have had similar on both my 2008 and 2012 iMac. Both were fine from new, both developed it within a couple of years.

I assumed that it was due to condensation as I have my desk right by a window. I have no other place to put it.

Currently waiting to see if my new 2017 goes the same way. I have heard a lot of people have this type of problem with iMacs.
 
I also had very similar smudges on my Late 2013 iMac and Apple replaced the LCD panel under AppleCare. This is why AppleCare is essential.
 
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