Yellow tinge from bottom to top of the screen, 27" iMac

BTW, a good 800 of my Posts have been on this iMac. That's Incredible! I need to get a Life! 🙂

PaoloS wrote:
But I still have some doubt about this hypothesis: being each pixel composed of three (RGB) LEDs, if all of them emit less light the result is a very light grey instead of pure white, but still a neutral color.

PaoloS, that's unfortunately not how LED backlit LCD's work. If I'm correct, then there are basically two ways to backlight an LCD display with LEDs:

1. With an array of LEDs around the perimeter of the screen
2. With LEDs placed at a grid spaced behind the screen

Only those super large displays you see in stadiums have separate LEDs for each "pixel".

Since we observe a color shift (towards yellow) that means that the balance between the three RGB components is altered, as if some LED colours were more sensitive to temperature changes than others. Can this be the case?

Could be, I'm no expert on this subject. Let's assume that temperature is a variable, then it would make sense that the color shift is vertical: the heat is transferred upwards within the iMac body and released at the top. It would be interesting to see when I rotate my iMac upside down (my iMac is on a VESA mounted arm with a pivot for rotating it), or lay it flat. I might try that tomorrow. The heat dissipation will be hindered this way (it was obviously designed to release the heat from the top, going upwards), but in the worst event the fans will kick in to get rid of the hot air.
It might well be that the screen is not tinted yellow at the bottom, but rather tinted blue at the top. Heat could make the screen more 'blueish' (I have no proof for this).
From some the pictures I've seen in this thread, many have a more yellow right-bottom area as well. Looking at this picture:

http://s1.guide-images.ifixit.com/igi/TLfSqZEZWnTwKylR.large

...it seems as if there's not anything 'hot' in that area (BlueTooth card?).

Someone with decent knowledge of LCD technology could probably shoot holes in my hypothesis within seconds though.

What bothers me, is that people say that when they change their viewing angle (to lower), they can make the 'yellow tinge' disappear. I see the same thing here, although I can't say it totally disappears. Could it be that some of the layers in the panel are causing some sort of refractive effect that causes the hue change? We need experts here...

They have had my 21.5" for a month now. They said they needed to "Capture" it for Testing. Many 21.5" iMacs have been sent back to Apple. That's an old story they keep telling. They KNOW the 21.5" has the Problem. I, as well as 150 other people on here, have made sure of that.

what about asking for a full refund?

How's Apple attitude for "non online" purchases?

I'm not sure? Anyone? If you bought it from a Reseller, like I did, I don't think that is offered as an option. But I'm not sure.

This is an Italy-specific post, sorry about that.

renzopanta wrote:
what about asking for a full refund?

This is a link to a document (sorry guys/gals, it's in Italian) describing warranty rules in Italy (should be the same all over Europe anyway): http://www.mdc.it/documenti/guidagaranzieweb_2.pdf

Basically it says that _if the defect is serious enough_, after a first repair or replacement you're entitled to a full refund; moreover, in the first two months it's up to the seller to prove that the defect wasn't there from the beginning (later on, it's up to you to prove it was).

_If the defect is not that serious_, as in the case of a slightly yellow screen (unless you're a professional photographer/graphics artist) and neither repair nor replacement could solve it, you're entitled to a partial rather than full refund.

All of this in theory, of course, since the difference between legality and reality in Italy is often striking, notably when trying to have someone's money back (it's sad to admit this in front of an international audience)

How's Apple attitude for "non online" purchases?

Having bought mine online, I was offered at least twice a full refund as an alternative to replacement; so to that respect Apple is playing very fair.

For non online buyers, you cannot obviously ask Apple to refund you, but if you find the seller doesn't support you enough, give AppleCare a call, you'll find a good support and a professional attitude (but remember: cell phones are charged much more than fixed ones)

Ciao, Paolo

I bought the iMac 27 (week 46) and the new Macbook pretty much at the same time late November. The first couple of weeks I was using the Macbook and doing not much with the iMac. Bottom line my 14 days return right was gone. Now here I am with an average yellowing on the bottom of the screen.
Based on what I read here, if I call Apple they would offer me repair, or replacing the screen.
Here is my question: doesn't it bother you guys that a new computer is taken apart in the back of the store? Then a new screen is installed that is probably not better than the old one and as if this is not enough, eventually the aluminum case is scratched, etc.
Considering I have the 3 years Apple care plan, what are my chances they would exchange the whole thing. Or how about I wait another few months until Apple sorts things out.

Saturday I took my fourth iMac 27" back for a full refund. I had called ahead and let them know I was coming and after number four they didn't even bother to open it and look at it...it could have been a box full of bricks for all they knew! The genius I had this time was remarkably forthright, and when I told him I was on number four he said "ah, you're doing well!" then proceeded to tell me that the problem had been fixed and that any iMac sent in for repair would get a new screen that was of different manufacture. He said "So if you want to buy a new one, we can open it and take a look at it, and if the screen is bad we can check it right in for a replacement." While I appreciated his candor, I thought that solution was a bit absurd for a brand new machine. Still, I guess its something.

On the same trip my friend picked up his replacement 27" iMac (I was his ride) as the screen on his first one had completely died after two weeks. Apple got him a full replacement and even did the data transfer for free, but his week 7 replacement had the yellow problem (not very bad, but present) and some dust particles behind the glass in the lower right hand corner. He's not sure yet if he is going to return it or not.

So here I sit with money to spend but no machine to spend it on. I'm going to wait for the shipping time at the apple store to go down to 24 hours, then wait two weeks just to be sure and check out preliminary reports, then order one direct. In the meantime, not having a computer at home is killing me slowly... 😉

Mike, you made the right choice. Be Patient! When the smoke clears you'll get what you want. Now your friend wound up with the same problem all over again. Again, be Patient.

sundisk, Yes it bothers me so much that I would not let Apple replace my Screen. Again, mine only shows Color Variance defect with Grey Bars up, so I'm OK & very satisfied, since I was upgraded from the base 21.5 Model to the 27" AT 1TB Model. I'm not allowing some sloppy technician's paws on my beautiful iMac. 🙂 I would scream if I got it back with Fingerprints, Scratches & Dust. I'm incredibly fussy with my equipment, so having anybody open it up unless it was DOA, is out of the question. Call Apple & tell them and first see what THEY say. Then if they say repair screen, tell them you would rather a replacement. Negotiate.

Dino, there we go. You are exactly like me. Jut thinking that someone would take the new iMac apart makes me sick. But the question is what to do? Are you going to keep it the way it is and just not think about this "yellow" business? Have you talked to any Apple rep about exchange? Which production week is yours?
On another note, I read some comments about the relationship between temperature and the yellowing of the monitor. I guess this may be the case, because when I turn the iMac on, for the first 3 minutes (being cold) the display is perfect. After 3~4 minutes the bottom of the monitor starts to turn yellowish.

sundisk, mine is a Week 06. I don't see any yellow or Color Variance when I'm using my iMac. The only time I see it, is if I run that Grey Bar Test. And it's not Yellow, it's a Color Variance. I'm not a Photographer or a Graphic Artist. My screen looks perfect full screen in Safari. I know what Yellow looks like. I had 2- iLemons in a row. This one is not Yellow. So yes! I'm keeping it. IMHO, I think these LCD Screens are sensitive & get misaligned during rough Shipping. Not enough protection in Packaging. I told Apple that, but they said, they test all their packing. But did they drop it from a 10 Ft High Truck & throw it like UPS & FedEx do? I doubt it! 🙂

I received a call tonight from my local Apple store that my iMac was repaired and is ready for pick up (dropped it off this past saturday). I was impressed with the turnaround time to repair. I ask what was done and the Genius said a display replacement and testing. I didn't bother to check the display in the store. Once home I turned the unit on and let it stand for an hour or so before I calibrated the display. I am pleased to announce that so far I can not see the yellow tint after running through all the tests! It was so obvious of the problem with the old panel in. I'm calling it fixed. I feel so bad for people who have been through numerous whole unit replacements only to see nothing is being resolved for them. I guess I'm lucky or Apple truly has got the fix for this. I hope you all have the same experience if you decide to do what I did this week. Good Luck.

Message was edited by: Paguyo

Message was edited by: Paguyo

I received my iMac i7 yesterday (two weeks before scheduled delivery date). It's a week 09 model from China, and it also has the yellow tinge at the bottom/right of the screen. I was hoping problems would've been resolved by now, but the tinge is just there. I'm not paranoid, it's clearly there.

I'm getting a replacement machine. Let's hope it stays with just one replacement. I'm having flashbacks to the Alu Powerbook G4 white-spots issue back then...

"I feel Apple is far too incompetent and focused on stupid little gadgets like the iPhone and iPad to every properly resolve this problem."

Yes it seems that Apple is not focused on computer anymore. Phones and gadgets are making far more money I think...