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darkus

macrumors 6502
Original poster
Nov 5, 2007
380
151
I have a significant amount of yellow tinting on the 30” Cinema Display and it’s worse at the left and right edges. From some google searches, what I understand is that it might be coming from a plastic diffusor screen that sits on top of the backlights.

If that’s true, it seems like it could be a straightforward fix.

But I have no idea where to source such a piece of plastic, or what that piece actually is.

So I figure I’ll ask here first and see if anyone has experience fixing this, or if the yellow tint comes from something else?

I’m planning on opening the screen tommorow and see what it is for myself, but any advice on this and more importantly where to source such a diffuser would be really appreciated!
 

uller6

macrumors 65816
May 14, 2010
1,036
1,661
Most diffusers are textured polycarbonate sheets. I have no idea where to source one, but good luck! I recently took apart an Apple Thunderbolt Display LCD and it was...tricky. Luckily I wasn't planning on putting the LCD back together again, but I'm not sure I would have been able to do so successfully, and I've done a lot of hardware hacking in the past.
 

darkus

macrumors 6502
Original poster
Nov 5, 2007
380
151
Most diffusers are textured polycarbonate sheets. I have no idea where to source one, but good luck! I recently took apart an Apple Thunderbolt Display LCD and it was...tricky. Luckily I wasn't planning on putting the LCD back together again, but I'm not sure I would have been able to do so successfully, and I've done a lot of hardware hacking in the past.
Thanks! I actually got some retro-bright and Im going to try whitening the anticipated yellow screen first. If that fails, then I'll try to order a new sheet depending on the dimensions of the sheet when I get it opened up.

This screen is so yellow, I figure I have nothing to lose by opening it up and trying to fix it. Will update, depending on what I find.

If there is no update then that means I've broken the monitor and am frustrated and never want to look at this thread again :) 😂
 
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darkus

macrumors 6502
Original poster
Nov 5, 2007
380
151
Well, just a follow up post for anyone out there that is thinking of the same.
I successfully opened the display and got down to the diffuser sheets, it probably took about 20 mins being careful. Most difficult thing is keeping track of all the various sized screws.

once I got in there a few of them were quite yellow. The top layer was about a gold color, it might be part of the design of the sheet and not actually yellow from use. I wasn’t sure. I simply removed and discarded this sheet altogether. I successfully whitened the back most diffuser Which was only slightly yellowed.
I put it all back together and…

success!
screen looks great. Now I’m going to try to add 2 more of displays to my setup 😊👍
 

Sharky II

macrumors 6502a
Jan 6, 2004
957
345
United Kingdom
I’d love to hear more about this…. Did you take any pics!?

What did you clean up and what did you brighten?

How exactly did you brighten up one of the layers?

Thanks!
 

darkus

macrumors 6502
Original poster
Nov 5, 2007
380
151
I’d love to hear more about this…. Did you take any pics!?

What did you clean up and what did you brighten?

How exactly did you brighten up one of the layers?

Thanks!
I didn’t take any pictures but I have it all memorized so I can probably provide some detail if needed.

for brightening I used retro bright.

Tbh, the white layers weren’t very yellow at all so it didn’t take much work. I think most of the difference came from simply tossing out the top most gold layer. To my eyes it looked like it was designed to be that color. Maybe apple was keen on blue light way back then and was trying to give a more war, tome on purpose?
 
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Sharky II

macrumors 6502a
Jan 6, 2004
957
345
United Kingdom
Great, did it brighten up the screen too?

Once calibrated my screen needs to be run at 100% to match my non/less yellowed ACD @ ~50% brightness.

Then, when it's hot, the screen would then slowly dim as it couldn't handle it. I always thought I was imagining it, but I actually had a calibrator on it and kept taking a ready and saw it drop to about just under 100cd/2 at max brightness.

This means the screen is using 150W of power and is very hot.

I suppose this could be a separate issue, in my case... maybe a power inverter or backlight issue. The screen is quite perfect (no smudging like my other screen), so it's a shame.

I'd also be curious to know if anybody has any info on the purpose of the gold sheet?
 
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JulianGray

macrumors newbie
Jun 28, 2018
14
8
Los Angeles
I didn’t take any pictures but I have it all memorized so I can probably provide some detail if needed.

for brightening I used retro bright.

Tbh, the white layers weren’t very yellow at all so it didn’t take much work. I think most of the difference came from simply tossing out the top most gold layer. To my eyes it looked like it was designed to be that color. Maybe apple was keen on blue light way back then and was trying to give a more war, tome on purpose?
Just picked up one of these displays and i'm thinking about doing the same, Did you just follow the ifixit breakdown to get it open?
 

llessurb

macrumors newbie
Feb 22, 2023
1
1
@JulianGray Did you end up trying to open up your Cinema Display using the ifixit teardown instructions? Or another walkthrough? I really want to try to remove the gold diffuser that @darkus removed. Mine has that yellow tint and it looks worse next to my other 2 screens, so I’m hoping to at least get it back to white. But otherwise it works great still after almost 18 years, so I’m wary of opening it up just for that.
 
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Sharky II

macrumors 6502a
Jan 6, 2004
957
345
United Kingdom
Also - does anybody know how to get rid of a 'smudge'? I assume this is pressure somewhere?

I actually sold the 'warm' ACD and have kept the 'good' one, which calibrates pretty well. I have noticed that the right side of my screen is ever so slightly warmer than the left - most people wouldn't notice, and it's an old screen now. I suspect this is down to age and tolerances.

But the smudge on the left is distracting, it doesn't show on all colours, and is a quite exaggerated in this attached photo vs real life. Maybe I've just learned to ignore it.

Given the amount of power the ACD30 uses, its' probably best to sell it and move on...
 

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Diff.eren.t

macrumors newbie
Nov 16, 2021
3
0
Well, just a follow up post for anyone out there that is thinking of the same.
I successfully opened the display and got down to the diffuser sheets, it probably took about 20 mins being careful. Most difficult thing is keeping track of all the various sized screws.

once I got in there a few of them were quite yellow. The top layer was about a gold color, it might be part of the design of the sheet and not actually yellow from use. I wasn’t sure. I simply removed and discarded this sheet altogether. I successfully whitened the back most diffuser Which was only slightly yellowed.
I put it all back together and…

success!
screen looks great. Now I’m going to try to add 2 more of displays to my setup 😊👍
Hello

I have Apple Cinema Display 30 inch too. How could you whiten the yellow sheet ?

Thanks a lot
 

darkus

macrumors 6502
Original poster
Nov 5, 2007
380
151
Just picked up one of these displays and i'm thinking about doing the same, Did you just follow the ifixit breakdown to get it open?

@JulianGray Did you end up trying to open up your Cinema Display using the ifixit teardown instructions? Or another walkthrough? I really want to try to remove the gold diffuser that @darkus removed. Mine has that yellow tint and it looks worse next to my other 2 screens, so I’m hoping to at least get it back to white. But otherwise it works great still after almost 18 years, so I’m wary of opening it up just for that.
Yup I followed the ifixit instructions
 

darkus

macrumors 6502
Original poster
Nov 5, 2007
380
151
Also - does anybody know how to get rid of a 'smudge'? I assume this is pressure somewhere?

I actually sold the 'warm' ACD and have kept the 'good' one, which calibrates pretty well. I have noticed that the right side of my screen is ever so slightly warmer than the left - most people wouldn't notice, and it's an old screen now. I suspect this is down to age and tolerances.

But the smudge on the left is distracting, it doesn't show on all colours, and is a quite exaggerated in this attached photo vs real life. Maybe I've just learned to ignore it.

Given the amount of power the ACD30 uses, its' probably best to sell it and move on...
This could be totally off base, but one thing I did notice when I was inside my screen was that the white plastic backing the lcd screen became yellow unevenly with the far right side in my case more yellow then the other sides.

There are physical lighting tubes in there (think of old halogen light beams in office buildings, but miniature) and I think these tubes are heating the plastic over time creating that yellow ness that comes across unevenly. That might be source of what you are seeing. But that’s just a guess out id thin air.

In my case, just removing the yellow film helped me since my yellowing on the back plastic wasn’t that bad. But if it does get bad I don’t know if there is any fixing it. It would be very difficult to bleach those parts, but I’m sure possible for someone really skilled with removing those lighting elements
 

roberthallin

macrumors member
Oct 25, 2009
92
27
Stockholm, Sweden
I've recently gotten a 30" Cinema Display that has a slight yellow tint on both sides of the screen but primarily on the right third towards the edge. The whole screen has a yellow tint, but it can be calibrated so that most of the screen pretty much matches my XDR-display in spite of this, but the tint is still noticeable on the right side. I was curious to see how this solution of yours is holding up after being in use for a while? I'll probably do the same thing to mine. Also I found this video, is it the plastic sheet at 11:38 that you used retro bright on?

 
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darkus

macrumors 6502
Original poster
Nov 5, 2007
380
151
@roberthallin
That video is great.

TL;DR ==> Mine is holding up AMAZINGLY well. No different from the day after I put it all back together again

The sheet I simply threw away (and I believe had the most effect) is the first one seen @ 10:25 in the video. Mine was really gold colored, reminiscent of the gold foil they use on space flights :) You can see the gold tinge on his, although when he brings it up to the camera his looks more milky white. Could be the lighting.

As for the yellowing more towards the right of the screen, that will liekly be due to either the multiple sheets underneath (10:53+), the hardened plastic diffusor (11:40) OR the white backbase plastic (11:42) (behind the backlight bars). His hardened plastic diffusor is REALLY yellow, mine wasnt that bad so it whitened up very easily. My backbase plastic had uneven yellowing, also I believe more towards the right side of the screen.

I did not try to whiten the backbase because I didnt want to damage the lighting elements as I have no idea how to get replacements for those if I did. I think it COULD be done, but you will have to be meticulous about it, because you have to get your fingers in between the light bars. I also cant imagine what would happen if I got some retrobright onto those lighting bars by accident and forgot to wipe it all of and then turn on the monitor and they heat and something bad happens. I just don't know enough about these chemicals to even experiment.

As for my results, they have held up AMAZINGLY. My yellowing was just not that bad, and I do believe the majority of the effect came from me tossing the gold tinted upper layer which may have come from the factory that way since it was very evenly yellow/gold colored.

On a side note, I used a product actually branded as "retrobright" but retrobright just refers to whitening of old plastics using a variety of different chemicals. After doing some of "my own research" ( :) ) into this, I wish I had used some of the more homemade versions, because the one I used seemed to very mild in activity and had a very gel like base that needed multiple applications to get really white. Some food for thought that might help you.
 
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roberthallin

macrumors member
Oct 25, 2009
92
27
Stockholm, Sweden
@roberthallin
That video is great.

TL;DR ==> Mine is holding up AMAZINGLY well. No different from the day after I put it all back together again

The sheet I simply threw away (and I believe had the most effect) is the first one seen @ 10:25 in the video. Mine was really gold colored, reminiscent of the gold foil they use on space flights :) You can see the gold tinge on his, although when he brings it up to the camera his looks more milky white. Could be the lighting.

As for the yellowing more towards the right of the screen, that will liekly be due to either the multiple sheets underneath (10:53+), the hardened plastic diffusor (11:40) OR the white backbase plastic (11:42) (behind the backlight bars). His hardened plastic diffusor is REALLY yellow, mine wasnt that bad so it whitened up very easily. My backbase plastic had uneven yellowing, also I believe more towards the right side of the screen.

I did not try to whiten the backbase because I didnt want to damage the lighting elements as I have no idea how to get replacements for those if I did. I think it COULD be done, but you will have to be meticulous about it, because you have to get your fingers in between the light bars. I also cant imagine what would happen if I got some retrobright onto those lighting bars by accident and forgot to wipe it all of and then turn on the monitor and they heat and something bad happens. I just don't know enough about these chemicals to even experiment.

As for my results, they have held up AMAZINGLY. My yellowing was just not that bad, and I do believe the majority of the effect came from me tossing the gold tinted upper layer which may have come from the factory that way since it was very evenly yellow/gold colored.

On a side note, I used a product actually branded as "retrobright" but retrobright just refers to whitening of old plastics using a variety of different chemicals. After doing some of "my own research" ( :) ) into this, I wish I had used some of the more homemade versions, because the one I used seemed to very mild in activity and had a very gel like base that needed multiple applications to get really white. Some food for thought that might help you.
Thanks a lot for that! As your procedure seems to be the only one I can find from someone who's actually attempted to sort the issue out I'll most likely just copy it and see what happens. I will not get into messing with the backbase either, it seems like that should have the least effect on the tint although I honestly have little to no idea about how these issues arise. I live in a country where retrobright is not available so I'll end up using one of the many recipes I've found online to cook up some of my own. From what I've read one needs UV-light for the procedure to be effective, and seeing how us Scandinavians aren't too spoiled with that this time of year this project will have to wait until summer, but I'll post back if I succeed. Again, thanks for a very helpful post for us with the ambition to keep these screens running for a while!
 
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