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Greyish Smudge marks behind the glass screen.

I have a 21.5 iMac bought in November 2009.

There appears to be numerous greyish smudge marks behind the glass screen on the top left hand corner.

It was not apparent to me at first, but after I started using OMMWriter it became easily visible. I also tried placing a neutral white background like TextEdit and it was easily visible even then.

I have cleaned the screen on numerous occasions and it has not had any effect.

What should I do?

These spots are quite disturbing.

iMac 21.5, November 2009, Mac OS X (10.6.2)

Posted on Jan 15, 2010 10:55 AM

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Posted on Jan 15, 2010 2:06 PM

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Dennis
1,291 replies

Dec 22, 2011 10:10 AM in response to Omek

I'm starting to think the only way Apple will recall these iMacs is if they start bursting into flames.


They would probably say it's due to some environmental factor! "Is your iMac located near a window?" ... "Yeah, that's probably what caused the spontaneous combustion then. Sorry but we can't repair since it's your fault!"


(to be clear, the Apple Store near me was extremely helpful and accomodating when I first took in my iMac with the screen smudges, so I can't complain too much about their service! But I've read horror stories from others on this thread where they got turned away from covered repairs due to the "environmental" line...)

Dec 22, 2011 10:24 AM in response to Omek

Omek wrote:


I'm starting to think the only way Apple will recall these iMacs is if they start bursting into flames.


You're right. There will be no recall.


Customer service has never been a strong point in any computer companies and Apple is possibly the worst.


I was about to think that it might have something to do with Steve Jobs being a control freak, but it was the same even during the years he wasn't around.


I sorta gave up on their customer service when I bought a PPC machine some years ago and the monitor was virtually DOA. But could I get a replacement? Nope.


The best I got was a refurb - 2 years older, which also went wrong. Only a week into the 90 days I should have got a replacement.


Bouncing back and forth between the reseller and Apple got me nowhere. I gave up on Apple for a while, and then came back for the iMac... Hmm.


I've recounted other cases on this thread with older machines. Same story.


⚠ I'm wondering if the other big company (beginning with S) who produce expensive all-in-one machines like the iMac have similar screen problems. Anyone know?


Might be worth perusing the competition's message-boards...

.

Dec 22, 2011 12:07 PM in response to Grace Munroe

After 3 imacs and several self repairs.


This is Most DEFINATELY a hardware issue. And PLEASE DO NOT TAKE APART YOUR SCREEN!!!. I've done it more than once... Let me explain:


FIRST THE EASY STUFF.

1. The smudges that are a problem are NOT located between the glass and the LCD which is easliy removed with a suction cup or two. and a bit of windex will clean that area in about 5 minutes... THIS IS NOT THE ISSUE.

2. Taking the screen out as if to replace a hard drive is fairly easy and there are instructions online to do this.

3. Cleaning the interior of your iMac is not too bad if your a little techie and VERY CAREFUL.

4. Cleaning a few pressure points or smudges between the LCD and the FRONT protective glass is easy HOWEVER if you leave even one little piece of dust or a streak of glass cleaner it will drive you insane.

5. 1 caviot. if you twist the screen when you take it out. you can permantly destroy it just because the little ribbon cables around the base of the glass are brittle from heating. Sometimes just disturbing the screen to change the hard drive will ruin it.


NOW to the core of the HARD STUFF

1 Mac Anatomy 101: There is a magnetized front protective glass cover. Then there is a LCD/LED screen underneath that. Once you unscrew the edges and remove all the ribbon cables it comes out in 1 piece.

This exposes the hard drive, mother board and fans and filth. inside the machine.

a. The SCREEN: In order to repiar these issues the actually internal screen must be disembled. This is normally done in a clean room. They are NOT DESIGNED TO BE TAKEN APART AGAIN...The actuall screen is made up of several layers. There is a Power supply/controller on the back of the screen. Then there is a metal box that contains a bunch of Ultraviolet lamps about 1/16th of an inch thick which will break if the screen is bent or twisted during dissembly. There is then a white ribbed light difusser which smooths out the light from the lamps so you don't see individual bright lines from the backlights.

There is then a polorizer/silver reflector/diffuser kinda piece of plastic. and Finally there is the actually LCD/LED glass. All of this is sandwiched together with a plastic spacer metal tape, regualr tape and sometimes sealed edges.


2. The PROBLEMS:

a. Dark smudges sometimes grey sometimes brownish. Ultra find dust and smoke particles are between the LCD and the the 1st layer of plastic. These can be cleaned off once the screen i dissembled.

b. Dark yellowed lines horizontally across the screen. These are yellowing on the Ribbed Difusser due to heat from the lights and power supply. This is not repairable. This yellowing can be removed a little with an anti-oxidizing agent like the lens cleaner for headlamps and A LOT OF RUBBING... be careful this difusser is brittle and will crack easily and then you're screwed.

c. Dark Hazy Horizontal lines. These are usually also due to smoke/dust particles inside the screen and can be cleaned off with windex or the like.

d. Colored lines and dark tiny 1 or 2 pixel lines on the screen: These are caused by heat and are not repairable. The surface mount ribbon cable that attaches the edge of the LCD are damaged. They can sometimes be re-flowed if you dare heat the heck out of your screen with a heat gun. HOWEVER usually this is a bad idea unless you're really an expert or unless you're really desperate and the success rate is less than 50/50. This often happens after someone like me has tried to clean the screen and even though being very careful has bent the little ribbon cables even a tiny amount (they are brittle and old and damaged due to heat already. sometimes just touching them will cause the problem.

e. banging on the screen or Twisting the screen from by grabbing the corners causes little lines to appear or disapear. Same problem as d. above. Your on your way to a permantly destroyed screen... hang it up and cry.


OK there you have it...

Good luck folks and never ever buy an imac older than 2 years or so... The problem will appear in almost all imacs after the 3 year point. imacs have been plagued with problems from day 1 due to heating and this.


That being said. I love them and continue to buy used ones for great prices on ebay. The smudges are not a problem that will destroy your mac. They are just ugly. If you leave it alone and deal with the discoloration you will be best off and your mac will probably last 5-7 years. Or sell it on ebay to a fool like me 🙂

Dec 22, 2011 1:08 PM in response to timfrombrisbane

timfrombrisbane wrote:


As much as I would love to sift through the 32 pages of this thread, can anyone clarify if this is an issue where there is some sort of condensation on the inside of the glass?


iMacs ventilation pulls air from down near the speakers to be ejected at the top of the machine. So in a humid environment, the iMac screen may become cloudy of smudgy on the inside.


To work around something like this I have found that leaving the computer on at full brightness for several hours in a low humidity environment gets rid of this issue and hasn't returned in the cases that I have looked at.


Hope I am on the right track 😝


My conclusion based on the information in this thread is that this grey smudge issue can be a number of things, and it is possibly near impossible to decipher if a cosmetic fix as I previously suggested will work. You just have to try it and see.


You mentioned a very important additional point. Often screen burn-in marks, which are grey as well, will appear. In my experience these marks look slightly different than the grey smudges discussed in this thread. Screen burn-in marks take on a shadow, traced like look. They will appear as a faint shadow traced portion of a previous wallpaper image, your dock, a Finder window or a desktop icon. And yes Tim, your fix does work - yet I recommend doing it slightly different. Download a blank white screen image (search on google for a large sized blank white screen image). Select this image as your screensaver, turn off your display sleep and crank up the brightness. This takes many hours, sometimes overnight, and it is not the greatest thing to do if you are trying to preserve the age of your screen, yet it is the only thing that will work to get rid of these particular grey marks. And this fix, unlike the other quick fix I recommend works 100% of the time.

Dec 22, 2011 1:40 PM in response to Steve876


Steve876 wrote:


PLEASE DO NOT TAKE APART YOUR SCREEN!!!.


1. The smudges that are a problem are NOT located between the glass and the LCD which is easliy removed with a suction cup or two. and a bit of windex will clean that area in about 5 minutes... THIS IS NOT THE ISSUE.




It was late when I was responding to this thread initially - lol. I left out an entire sentence which resulted in my advice being very misleading. I meant to say that the smudges, in my experience, were beneath the next layer down - the thin plastic layer, getting pushed against the layer beneath it. Taking apart the screen has fixed the problem 100% of the time. So it's ill-advised to insist this will not help. Yet that being said, taking apart the screen is not something that a non-technical person should do.


Also - regarding buying a used iMac. Buying a refurb iMac from Apple is like buying a new iMac. Chances are the screen is new. Also, and most important, you have the same 1 year built in warranty and the option to purchase extended AppleCare as you would a new computer. The thing I would not advise is buying an iMac on Ebay without AppleCare.


🙂


Message was edited by: pianoman1976

Dec 24, 2011 3:13 AM in response to Grace Munroe

Well, my computer worked fine whilst I had the problem, as you'd expect really. The smudge was a distraction, nothing more.


You know what I want for Christmas? A way of making this discussion go global, in the same way that 'bumpergate' did for the iPhone 4. I've got one of those, and I advertise it to friends as "The iPhone. Great pocket computer, naff phone". Looks like the iMac is going the same way. There's no way I could recommend one of these to a friend now.


Anyway, if we could get the same level of media attention for this problem as bumpergate, we'd be fixed. But I guess it ain't gonna happen. Thoughts?

Dec 24, 2011 7:43 PM in response to pianoman1976

These posts are amazing. I wonder if Apple techs read them? lol. well the mark on my screen has gotten bigger. I hope that this will be the only issue and that I will get another five years out of it considering it's my second replacement. having said that I may go for a mini mac next time and buy a different type of monitor. does anyone know much about the mini mac or if there are any concerns with hooking it up to a monitor that isn't apple? maybe this will be a resolution for my next time around and I never recomend apple products to my friends now. unfortunatley despite all of this I still love everything about how an apple computer operates.

Dec 24, 2011 8:47 PM in response to Grace Munroe

Grace Munroe wrote:


having said that I may go for a mini mac next time and buy a different type of monitor. does anyone know much about the mini mac or if there are any concerns with hooking it up to a monitor that isn't apple? maybe this will be a resolution for my next time around



You don't have to stick with an Apple monitor for your Mac Mini (or the Mac Pro), yet imo Apple displays are far superior than the competition. They look stunning. In fact, this seems to be a defining trait of Apple's - incredibly beautiful, crystal clear displays! I have family and friends who are graphic designers and they would never dream of using anything other than an Apple display.


Isn't the problem we are discussing here isolated to the iMac? Just because the iMac screen seems to be prone to trouble (prolly due to the nature of the iMac compact build), does not mean that the Apple Cinema and Thunderbolt displays are troubled as well, does it? I haven't heard anything negative in that regard, yet I haven't researched it.

Dec 27, 2011 5:57 AM in response to Grace Munroe

At one point in this huge thread I think it was discussed that the iMac is unique in its design with fan intake on the bottom base of the monitor which has no filter so it inhales everything around it. And the iMac has hardware packed-in behind it that causes a lot of heat. Apple's Cinema display has neither fan ports nor the kind of hardware that exists in the iMac, so it doesn't generate nearly as much heat nor does it suck-in dusty air. I haven't done any research on issues with the Cinema display but I have to imagine it wouldn't be experiencing the kind of problems as us iMac owners.


But who wants a Mac Mini powering their beautiful screen! 😉 I had a Mini for a while and I loved it (used a regular Samsung monitor with it, any will do), but this quad-core i5 and discrete graphics card just blows it away.

Dec 28, 2011 8:34 AM in response to BinaryMango

I'm having the same issue on my 27" imac. I have grey marks looking almost like liquid running down from the top. It covers over 1/3 of my screen and is a real issue. Brought my computer in and because it's 52 days past my warranty (had extinuating circumstances not allowing me to make it into a store under warranty period) I'm having to pay for a replacement screen and it's only going to come with a 90 day warranty. I am guessing it has to do with the amount of heat on the top 1/2 of my imac. I've been turning the computer off everytime I'm not using it and today after having it on for about 30 minutes I noticed that the center of the screen started to get a haze that was growing. I tried to wipe off the outside but it seems to be on the inside! I'm very dissapointed in my 27" imac! This is the 3rd apple computer I've purchased, all in the same room and I got the same it's an environmental factor excuse but we can all tell that it has something to do with the specific design. I really wish apple would step up to the plate with the people who are having issues on a $2,200+ computer...I know for one I can't afford a $600 screen replacement every year...

Greyish Smudge marks behind the glass screen.

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