My theory on the Yellow Tinge - The Cause.

tomacintosh

macrumors regular
Original poster
Aug 25, 2005
234
0
After reading all the posts regarding the yellow tainted screens. I got my iMac fearing the worst. Upon first inspection the display seemed fine, but once I started it using it for a few hours I started to noticed the bottom right hand quarter of the screen was no way as white as the rest. Upon using the grey testing image, my screen actually does have minor yellow tinge. It's not really enough to put me off, but I can notice it.

Then I thought to myself, is this problem brought on by heat? Are the CPU and GPU thermal spots causing discolouration to the display? Both are located near the bottom of the screen, and that seems to be where 90% of the problems are?

Have Apple put enough shielding between the screen and components?
 

IndustrialSpace

macrumors 6502a
Dec 31, 2009
696
1
somewhere
Why does the imac have to be THAT thin?

After slimming them down so much, is it even possible for them to go back to a beefer deisgn without losing face?
 

All Taken

macrumors 6502a
Dec 28, 2009
780
0
UK
Read grasshopper.

He wrote

While not worded as theory but more like a question, it does appear to be his theory.
Thanks for the clarification. I was looking forward to reading his theory and was presented with questions instead.

Perhaps a change of title?
 

All Taken

macrumors 6502a
Dec 28, 2009
780
0
UK
My own theory is that the display is faulty and the heat from the unit is not the root cause (It may cause progressive "yellowing"). My theory is backed by the fact that the new unit I received had a yellow tint issue.

How can a brand new unit have a yellow tint issue if it has not been subject to heat?

Apple need to engage with LG on the faulty screens.
 

Bitwise

macrumors member
Jan 1, 2010
75
0
Portland, OR
My theory is that the manufacturing facility received a load of bad screens from LG. QC got bored with their jobs and decided to take a nice long nap. As a result most of us have super sweet yellow displays!
 

All Taken

macrumors 6502a
Dec 28, 2009
780
0
UK
How much heat do you think the iMac is producing under test? How long do you think the iMac is subjected to the heat? Long enough to turn the display yellow?

I think it is much more plausible that LG are supplying defective screens.
My first unit had a High Pitched noise issue (PSU problem) however the screen was fine, how would your theory account for some units having yellow screens whilst others don't? All iMacs would under go the same testing/quality control regardless of where assembled.

In my opinion.
 

Travisimo

macrumors 6502a
Dec 22, 2009
985
223
Then I thought to myself, is this problem brought on by heat? Are the CPU and GPU thermal spots causing discolouration to the display? Both are located near the bottom of the screen, and that seems to be where 90% of the problems are?

Have Apple put enough shielding between the screen and components?
Are you sure that is the hottest place behind the panel? I don't know where the components are located, but when I place my hand on the back of my 27" iMac, the HOTTEST place by far is in the upper left corner (when you are looking at the screen). Maybe this is where the power supply is located? The upper right corner is also pretty warm, but the lower half of my iMac is the coolest, so it IS an interesting theory (since the yellowing gets progressively worse from top to bottom). Maybe the extra heat is actually causing a BLUE tinge and the YELLOW tinge is actually the normal tint. LOL.

At any rate, I often wondered if the LED backlights may be affected by heat but I'm not familiar enough with the technology to know whether this is the case. However, I'm with the others that it's more likely just a defect in the panel itself.
 
My theory is that the manufacturing facility received a load of bad screens from LG. QC got bored with their jobs and decided to take a nice long nap. As a result most of us have super sweet yellow displays!
This reminds me of that Simpsons episode where Homer visits the Duff brewery and while congratulating the quality control guy, beer bottles with rats, syringes, and Hitlers head in them roll on by down the assembly line.
 

WilliamG

macrumors G3
Mar 29, 2008
8,987
2,399
Seattle
You guys are hilarious with your theories. My 24" LED Cinema Display tinges yellow toward the bottom, and I'm pretty sure there's no GPU in my display! ;)
 

Sir Cecil

macrumors 6502a
Mar 31, 2008
793
0
You guys are hilarious with your theories. My 24" LED Cinema Display tinges yellow toward the bottom, and I'm pretty sure there's no GPU in my display! ;)
The common-denominator might be as simple as something like some pressure on certain points of the panel from the glass, due to the way the panel is fixed in place (i.e., not being absolutely 100% flat behind the glass and being pressed at certain points).
 

mtnDewFTW

macrumors 6502a
Oct 26, 2009
875
66
San Francisco, CA
Yeah, but some people have gotten that problem on half of the entire screen.
not just the bottom right side.

So, sure, your theory would make sense, if every one got that problem in the same spot.
but that's not the case, so I can't say that this is anywhere near valid.
good guess though
 

AAPLaday

Guest
Aug 6, 2008
2,414
1
Manchester UK
My iPhone has a yellow tint on it. Not huge but it's there. Side by side my 1st gen Touch, the Touch has far better screen colour and stronger images. Obviously your talking about iMacs but let's not forget it affected iPhones too. Apple has a real problem with displays. The MacBook air line issue as well for example.
 

Kronie

macrumors 6502a
Dec 4, 2008
929
0
Exactly, and is that the GPU or the CPU just to the upper left if that fan?
 

All Taken

macrumors 6502a
Dec 28, 2009
780
0
UK
Before this thread turns into "THE IMAC GPU, CPU, FANS ARE BURNING YELLOW TINTS INTO THE DISPLAY!!!" take a second to calm yourself and have a really good think and a sit down.

How on earth can some displays be perfectly free and clear of the yellow tint issue? :rolleyes:

Your theories are void on that basis alone.

It's because LG are providing batches of defective panels.

I would also like to dismiss the crazy theory of the glass putting pressure on the Panel. I assure you this is not the case (See my tutorial for proof of claim - I have opened, I have seen).

You guys are hilarious with your theories. My 24" LED Cinema Display tinges yellow toward the bottom, and I'm pretty sure there's no GPU in my display! ;)
We need more like yourself William.
 

tomacintosh

macrumors regular
Original poster
Aug 25, 2005
234
0
Before this thread turns into "THE IMAC GPU, CPU, FANS ARE BURNING YELLOW TINTS INTO THE DISPLAY!!!" take a second to calm yourself and have a really good think and a sit down.

How on earth can some displays be perfectly free and clear of the yellow tint issue? :rolleyes:

Your theories are void on that basis alone.

It's because LG are providing batches of defective panels.
Or it could be that some screens are more resilient to the heat than others?
 

MH01

Suspended
Feb 11, 2008
12,118
9,213
Or it could be that some screens are more resilient to the heat than others?
My money is on made by the lowest bidder, and if you get a perfect screen but have some other issue, do not get a replacement, get it repaired, your really Lucky ;)
 

All Taken

macrumors 6502a
Dec 28, 2009
780
0
UK
I think that could be a valid point, however, with the evidence of some screens being free of any yellow tint do you not find it much more plausible that LG are producing batches of faulty panels?

I think there is a chance some panels are susceptible to heat issue either due to backlight heat or CPU heat, heck even a voltage issue. The only problem I have with that idea is that I am yet to read of a case where the iMac has developed a yellow tint issue.
 

Kronie

macrumors 6502a
Dec 4, 2008
929
0
How on earth can some displays be perfectly free and clear of the yellow tint issue? :rolleyes:
I still don't think there are. I think some people are more sensitive to it than others. All three of my i7's had yellowing, and some people I showed it to could clearly see it and some people couldn't find anything wrong with it.

If a 27" screen is yellow in the forest and no one is around to see it does it, is it really yellow?