What can make my screen shifts colors permanently?

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iMac Intel 27" Retina 5K Display (Mid 2017)

모델 A1419 / EMC 3070 / Mid 2017 / 3.4, 3.5 또는 3.8 GHz Core i5 또는 4.2 GHz Core i7 Kaby Lake Processor (ID iMac18,3) / Retina 5K Display. 시스템이 매우 유사하므로 이전 iMac Intel 27" Retina 5K Display (Late 2014 & 2015) 안내서를 참고하십시오.

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Piotr @wyszynski

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What can make my screen shifts colors permanently?

I have uneven colors on my screen. Left side is slightly dimmer and more purple, right side is a little bit brighter and more orange/green looking. Once this problem has occurred. Apple replaced my screen about 6 months ago. Now this issue is back so I'm going to replace it again under warranty but I'm starting to thinking that it's not the fault of bad screen. Can something else damage the screen that way?

Someone suggested to me that it might be fault of GPU heating but I don't have any problems with performance.

I added two pictures. One with boosted contrast and one with neutral colors.

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Dan @danj

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Yep! Your display does have unevenness.

As to the cause as you correctly identified the panel its self has issues, and will need to be replaced (under warranty I hope).

But why? This gets into the chemistry of the liquid crystals and how they work. You likely have played with polarizing sheets where you take two and if you twist them 90 degrees the light will be blocked and then twist them back sigh passes. Simply put, this is a comb filter that filters light that is going in different angles of the sheet. Well it turns out this is the exact same effect LCD displays use. The crystal normally blocks the lights transmission and when power is applied to it, it becomes untwisted allowing light to pass. Here’s a good vid thats shows the effect: https://www.youtube.com/watch?v=k7xGQKpQ...

OK, so the liquid crystals them selves are like valves flexing on and off letting the light through. But, just like a water faucet it can leak! Which can happen here as well. If the crystal is held at a position for long periods of time it can loose its ability to both loosen or to tighten allowing some light to pass as well as not fully block the light. This fatigue is more common on older displays do to age. But it’s not the only cause!

Lets change things here a bit and talk about TV’s they are constantly flexing the crystals yet you don’t see this leakage within them why is that the case? Surprisingly it is! It’s simply the lack of the image from being fixed as long as we do with PC’s. This gets into the background image your Mac likely has running now with the default Sierra or High Sierra Mountain scene or what you’ve replaced it with. Which has some harsh extremes in both color and brightness throughout the scene.

So lets try this, using a plain neutral screen color so the extremes are not present. This will allow the crystals to be less stressed across the panel giving you more evenness of saturation. This won’t fix a screen thats already damaged but it will allow it to recover a bit. Also lower the brightness as well.

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Thank you for your answer! It's nice to understand all of this!

From my point of view two screens gone bad in the same way in 10 months. My understanding is that either screens in itself were faulty or some other parts are damaging them (like overheating GPU) or something which controls them is not working properly (power supply of LCD backlight? some chip that is responsible for displaying colors?). I want to understand this a little bit, maybe run some tests because probably if I just order repair then only screen will be replaced like the last time. If there is something different that may cause this problem then soon I will be out of warranty with badly made unit.

To sum up. Is this type of an issue could be caused by too much heat or faulty motherboard, power supply? Is there something that I could do to check this?

Piotr 의 2018년 7월 27일

The only thing would be sun beating down onto the display overheating the screen from the outside in. Do you have a window nearby that the sun can shine through hitting your display sometime during the day?

There is quite a lot of protection from the logic board side to the backside of the screen so I don't see that as the issue from heat or any other source of damage.

The backlight LED's are on the top & bottom edges of the screen so that too won't alter the inner parts of the screen from heat and they don't burn that hot.

The thickness of the liquid crystals can be different across the face of the screen which can effect the lights transmission. But you would note that when you bought the system or after you got your system back from repair.

Logic board (chips), Power supply, or home/build power issues are very remote and you would know as they would effect other things.

Dan 의 2018년 7월 27일

I do have my mac close to window but it’s back to window so there is never direct sunlight into the screen and most of the times I have covered windows when it’s bright day. Maybe couple of days in a year I might forget about covering the windows but then it would only shine on the back of the mac. On fcpx group someone suggested that it might be couse by close proximity of speakers and my creatives t20 are touching the mac from both sides. Sounds like myth but I think it’s worth mention it.

Piotr 의 2018년 7월 27일

LCD displays are not bothered by magnetic fields. I have two speakers mounted to mine no issues!

I promise you there is no environmental causes that you caused other than the sun overheating the screen (cooking the liquid crystal material).

That leaves the LCD Image Persistence which is what I suspect is the root issue. I tell people all of the time to forget the fun desktop images just use a plain color image with no texture.

Dan 의 2018년 7월 27일

Thanks Dan for your help. You might be right but wouldn’t that be a global problem then?

Piotr 의 2018년 7월 28일

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Thank you for your answer! It's nice to understand all of this!

From my point of view two screens gone bad in the same way in 10 months. My understanding is that either screens in itself were faulty or some other parts are damaging them (like overheating GPU) or something which controls them is not working properly (power supply of LCD backlight? some chip that is responsible for displaying colors?). I want to understand this a little bit, maybe run some tests because probably if I just order repair then only screen will be replaced like the last time. If there is something different that may cause this problem then soon I will be out of warranty with badly made unit.

To sum up. Is this type of an issue could be caused by too much heat or faulty motherboard, power supply? Is there something that I could do to check this? — Piotr
The only thing would be sun beating down onto the display overheating the screen from the outside in. Do you have a window nearby that the sun can shine through hitting your display sometime during the day?

There is quite a lot of protection from the logic board side to the backside of the screen so I don't see that as the issue from heat or any other source of damage.

The backlight LED's are on the top & bottom edges of the screen so that too won't alter the inner parts of the screen from heat and they don't burn that hot.

The thickness of the liquid crystals can be different across the face of the screen which can effect the lights transmission. But you would note that when you bought the system or after you got your system back from repair.

Logic board (chips), Power supply, or home/build power issues are very remote and you would know as they would effect other things. — Dan
I do have my mac close to window but it’s back to window so there is never direct sunlight into the screen and most of the times I have covered windows when it’s bright day. Maybe couple of days in a year I might forget about covering the windows but then it would only shine on the back of the mac. On fcpx group someone suggested that it might be couse by close proximity of speakers and my creatives t20 are touching the mac from both sides. Sounds like myth but I think it’s worth mention it. — Piotr
LCD displays are not bothered by magnetic fields. I have two speakers mounted to mine no issues!

I promise you there is no environmental causes that you caused other than the sun overheating the screen (cooking the liquid crystal material).

That leaves the LCD Image Persistence which is what I suspect is the root issue. I tell people all of the time to forget the fun desktop images just use a plain color image with no texture. — Dan
Thanks Dan for your help. You might be right but wouldn’t that be a global problem then? — Piotr

iMac Intel 27" Retina 5K Display (Mid 2017)

What can make my screen shifts colors permanently?

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