Q: Greyish Smudge marks behind the glass screen.

I have a 27 inch mid 2011 iMac. I bought it while living in Germany. I got the grayish smudges (but only on the right hand side of my screen). I had the display changed out under warranty but right at the end of the warranty. After it was changed a few months later I got the grayish smudges again. At this point it was no longer under warranty and I didn't buy the extended warranty. I started noticing black fuzzy stuff sticking to the back of the desktop. If I touched it, it would smudge. I talked to the place who handled my repair and they said it may be dust. Now in Germany we didn't have forced air heating so I couldn't figure out where it was coming from. I made sure to not burn candles in that room with the computer (just in case). Now I have moved back to the states was in an apartment for six months with forced air heating and central air did not have any problems with black fuzzy stuff even though I burned candles in the apartment. Now after buying a home and the computer only being set up for a week I am seeing the black fuzzy stuff again. Could this be the problem causing the grayish marks on the right side of my display? And what in the world is this black stuff and why is it so attracted to only the back of the computer? Also My iMac seems to be running really warm but only at the top.

Hi Heather

Some photograph of the screen would tell more...

It could be dust that is better because that can be removed.

But it can also be heat related just like in may case.

Is the smudge goes away whan the computer is cold??? Turn it down for a night next morning look at it while it is still cold, if it is clear than then is a heat issue (it will come back 10-20 minutes)

My heat caused mark were also in the right side of the screen

rockjano

Same issue here.

Bought a 21 inch 2013 iMac. After a few months, a grey smudge started to appear in the lower left corner of the screen. I'm in warranty so the display is going to be replaced...

Other than that I'm very pleased with the overall product. It's very well built and designed. I would very much like for Apple to look deeper into this issue, because it seem to be a recurring problem for many people.

Thank you.

That also seems to be heat issue...

Some update from my experience!!!

I put a new Seagate HD into my iMac and still no smudge... nothing so my smudge was heat related caused by the previous dying HD. It took a long time to die smudge was there for almost a year... but now it has completely gone.

I am a happy mac user again...  I just spent a lot of time with it (and the official service had no idea what caused the problem I also informed them)

rockjano

Grey smudges on my screen.

That looks like dirt.

If you are out of warranty (as I am) you can try to clean it yourself.

Daring process but it works... (except if it is a heat issue like I had, that cannot be cleaned :-)

rockjano

This is the black fuzzy stuff that gets all over the back of the commputer and makes its way into this area as well. I clean the back off several times a week and try and vacuume this area out but the smudges still came back. 

Interesting.

Well it is good to keep the machine clean but if dirt goes into the LCD unit than you have to take apart that. And clean it ...

How to clean the actual LCD screen and seal it properly so it doesn't stain again.

http://www.youtube.com/watch?v=8EY36MnPneM

iMac's are a total waste of money.

I had a 21 inch 2007 iMac for several years and had zero issues with it and it worked great. I only got rid of it because I moved out of country and just took my Macbook. Then I bought this because I got rid of my Macbook and figured I would have a desktop and just use my iPad around the house. If I can just get the issues fixed to stay fixed I would be a happy camper. I don't want to get rid of this one just yet because all of the new ones do not have the disk drive.

Aloha all,

Joining the bandwagon here!  Bought a Macbook Pro (love it!) and Thunderbolt display for digital art projects.  Used the monitor for 6 months and just noticed the appearence of smudges.  Have an appointment with phone support tomorrow.  Hope they back the guarantee I payed for on such expensive equipment.

Another iMac joining or rather rejoining the bandwagon. My iMac has had 4 failed LCD panels. The last one the 4th after 8 mos. AppleCare covered with a lot of trouble the first three. The current response now is that maybe I should buy a new iMac since this is old now and spend the extra $1500 on another failing product.

That sounds really crazy Ranand!!!

What were the problems with them?? Dirt or something else what were the simptoms???

(so ApleCare is nice but if it is a fundamental design problem nobody can really make enything...)

This strory is really a disaster for all of us (including Apple)

I think this is really a design problem. I also tend to think that desktop is not so important anymore for apple they just make waaay too much money with iOs devices...  (which is OK just don't forget the desktop crowd)

Each time it was a failed LCD panel. The geniuses told me repeatedly that I smoked, which I don't, have high humidity (23% very dry) dust which is nothing abnormal for the Sony and Dell displays don't die like these do. Mine always fails from the top right. It is where I was told the power supply sits. Apple customer service exec and AppleCare told me to get a new one but honestly don't want this product. Looks nice but is designed to fail.

Oh does geniuses :-)

The power supply I think is down (at least it is in my 27" imac) the top righ is the place of the DVD

Was the same problem allways the same? Did it come immediately when they changed the LCD or just after some time? Was it always on or just after some time if you turned on the mac?

My problem was a dying HD that caused my smudge which was NOT DUST but HEAT RELATED!!!

I have a new HD in and the problem gone.

You might have the same problem something is heating up in the machine and that could cause LCD problems and it comes back even if they change the LCD.

rockjano