Chosen Solution
Hello everyone, I just sold my “old” iMac 5k 2017 because it was out of warranty so Apple asked 650 Euro to replace the display because dust started accumulating in the corners. For the same amount of money I replaced it with the “new” iMac 5K 2019 and now I have Apple care so I have peace of mind for 3 years. As this is not a final nor elegant solution I would like to understand what causes this problem to some people over and over even with 2 or 3 replaced displays, but not for others. I also made some primitive dust filter out of blocks of open cell foam I placed between my desk and iMac so I would like to know what you think whether this is going to help with dust accumulating in the corners again. Here is how it looks:
How it likely happens is the screen is bonded with LOCA glue so it’s usually a factory defect or develops over time as the LOCA glue degrades as it ages. There is no cure as it fails as the system ages, unless it’s a factory defect. Test the new computer with a black test image and check it when it’s new, so you can tell apart age vs. factory failure. Short of living in an ISO certified cleanroom and wearing a bunny suit, it’ll happen as it ages again. Sadly there is no good fix since this is much more difficult to “debond” and correct since it’s much larger then an iPhone - it isn’t even a DIY job on the iPhone and other mobile devices, but anyone with pro experience can typically get it on the phones. This is beyond DIY and high experience.
Sadly, I think you’ve cooked your display! The backlight LED’s sit at the bottom of the panel. Overtime the lack of cooling causes the LCD material to loose its solution from evaporation.
This is sorta like how maple syrup is made from the maple tree sap by evaporation of the water in that case, as the liquid thickens to a syrup. The liquid in the case here so the LCD material gets thicker causing it not to react as quickly making it look muddy like yours looks along the bottom. Basically you don’t have a dust issue at all!
