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Model A1418 / Mid 2014 / 1.4, 2.7 & 2.9 GHz Core i5 or 3.1 GHz Core i7 Processor

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White stains on motherboard

I have an iMac that is not powering on anymore. After removing the display to inspect the interior, I noticed white spots in a certain area on the motherboard. I'm not sure if this is relevant to the malfunction as I've seen this on working boards as well. It's unlikely to be liquid damage as the screen seals the device pretty well.

What am I looking at here?

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That could e be a couple things could be corrosion which could be related to it not turning on could be a type of grease that is used for keeping moisture out but do don’t remember ever really seeing it on a iMac

I would try cleaning it away with some isopropyl alcohol and some cotton buds/Qtips

Hopefully this helps

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Huh, it's really curious that the two biggest spots have a very distinct semicircle shape. Is there any other component mounted right above the board there?



Yeah strange isn’t it

Apple used to use this grease powder stuff that looked a lot like on the photos but I remember it being used in the ram slots

From the photo it looks like where the cpu cooler screws on because the screw stand off things look similar


The semi-circles match the outline of the capacitors on the other side.

I'm guessing the system is used within a humid area or climate near the ocean as this looks like salt deposits.



That’s probably it!


@danj That's wildly interesting Dan as the iMac was sitting 2 rooms away from a pool. Any explanation as to why these salt deposits would form around a cap? Something to do with amount of heat from capacitors?


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