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Old Mar 23, 2012, 04:13 PM   #151
Timsi
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it was a Hair ;-)
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Old Mar 26, 2012, 10:34 AM   #152
Gebekophli
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Thanks to Oggy, I cleaned a 24" iMac early 2009

The first message for you guys here is: Apple is definitive not ignorant in this problem. But beating upon SAMSUNG resp. LG was not enough. They made (tried) changings in construction with every new model, but they failed in diagnostics and prevention.

Please, have a careful look upon the opened display housing:



You can see the high-degree-dust flares under the TFT-panel. And you can see periodical sun-beam-like free spaces in between the dust deposits. The "periods" are the analogons of the multi connectors slots.




I searched for one month in October 2011 and found at last Oggy's guide. Without his instructive pictures I would not have done it.
The cleaning went very well. But this alone would not make me writing here.
the dust didn't return after.

I searched very carefully for the way of the dust into the display housing.

I wrote a message to Apple on the support-sides messenger on 14th of Dec 2011:


Hello to the Staff!
This message is one of the rare you should respond to.

I'am Apple User in continuity since 1993 (PowerBook145B) and in my family we use 6 Apple Computers (5x iMacs and 1x Cube)
My message is not, that I cleaned the inner surfaces of the Display of my early 2009 iMac (VM932H420TM) by myself sufficiently.
My message is, that I found out, which way the dust flows inside until between the layers of the display.
In the display device LM240WU2-SLB4 he cover of LCD's electronics work like a collector for hot exausts coming out of the heatpipe air channel(s).
The pattern of preventive actions taken so far show me, that there is a lack of insight in the process of airflow.
The further path leads along the dust-carrying air the same way as the multi-conductors take from the electronic directly under the LCD panel, where the dust condensates or precipitates.
The Way along the 8 connectors is narrow, but the most relevant one. The reason, that former displays didn't had this decontamination-problem is, that the adhesive tapes on the electronic boards there didn't left a slot for the airflow.

I worked one month until I got the skills for cleaning and, much more of interest for you, on the problem to prevent re-contamination:
I sealed the whole upper third of the display device, so the electronic cover will no longer be a channel and collector for exausts.
Maybe you and LG will fix the problem now.
If you think, my information is worth to answer, you will do so.
Best regards from
G....



Of course they never responded...

This was just the PART I of my research.

PART II will tell you why air is forced to flow throughout the display housing.
And that, dear readers, is the reason, why Apple wants to get the whole system in return. You can't get the answer, looking only upon the display housing.

Last edited by Gebekophli; Mar 26, 2012 at 10:42 AM.
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Old Mar 27, 2012, 01:08 PM   #153
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Part II: The airflow in an iMac

You don't need special relationship to Apple Company, to get the knowledge,
that Apple developers learned very slowly, why display housings are collecting dust. You just need to look at the small modifications that have been added from generation to generation. Particularly revealing are the little ones senseless modifications.


Act I: 20"iMacs until 2006: The airflow was ruled by the center CPU fan, as it is like today. But at that time the inner parts became very hot. The air came inside the computer body from down under and went through the two heat pipes in the center. So far so well.
In this model the problem is on the left side: A smaller fan throws the air along the hard drive and along the power supply board after, which became really hot and often failed. Look at the next picture "Smokers corner": You see the beautiful yellowish nicotines flares in the upper part, on the left. You don't need to be an engineer to see, that there is something running damn wrong.





And please have a look under the display housing, left corner:



Why this heat? Where is it from? The answer is: there is an air flow short circuit: the air won't go out of the iMacs body on top. Not in that quantity it should do so.
Look at the upper slot covered with aluminum foil with very little holes, completely yellow from nicotine. You will easily believe, that everything suffers from the too narrow upper ventilation grid. THE HOT AIR RETURNS FROM THE TOP TO THE BOTTOM, from higher pressure to lower pressure at the bottom and becomes even hotter and hotter with every new circulation right through the fan again. That's the magic formula: THE AIR RETURNS FROM TOP TO BOTTOM and back again.

Apple is not in the fine situation to learn from old, worn-up machines. They only sit in front of new machines. Thats the reason they collect old machines now and change them generously against new machines. That yellow stains inside the worn-up old iMacs are worth of gold and more. My recommendation: Only hard-core chain smokers should get this advantage.
I'm non-smoker, to make political incorrect jokes about a beaten minority.

In any year before or in the year 2006 they made a first trial of stopping the air-flow-short-circiut: They added a foam plastic stripe under the display along a line: ODD - Heatpipe - HDD - Backlight power supply to prevent the air from returning to the fans again. But, there were gaps and slots enough in order to return. This iMac late 2006 was saved from boiling condensators on the power supply board or on the logic board like in the G5 iMacs before by a simple plastic foam strip.

Act II: The 24" iMac Generation from late 2006 (next foto) until early 2009 (the one after the next foto):





Stop, you will say, those iMacs are completely different! Let's have a look upon the things which are really different: During the next three generations very sophisticated changings in air flow management were experienced:

Here the late 2006: Some air barriers are built, but not very consequently, so they are not tight against back flowing air. Plastic-elongations at the fans and foam-stripes horizontally.



And they are definitely not airtight against back flowing air: The crude piece of foam is a blame.



Please compare it with the iMac 24" early 2009 2,93 MHz: The effort now deserves the score: serious and air tight:





And before I close this chapter for today, I tell you herewith, that you have acquaintance with the devil of the displays: The sufficient air pressure difference between top (high) and bottom (low). And remember: The way back is closed firmly.

Next Part III:

Last edited by Gebekophli; Mar 27, 2012 at 01:32 PM.
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Old Mar 27, 2012, 01:41 PM   #154
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Hmmm...

Well done for trying to find out the reasons why!!

But I must disagree with you on some points. Since Apple didn't bother to reply to you or nobody else in the world regarding this problem and explain what is the actual problem is pure evidence that they don't give a flying ******* about it.

They obviously did make some upgrades for the air flow. Witch you elaborate.

You haven't given us clue to why you think they did try to solve the sealing of the panels. Dust appears on 20", 24", 27" of all variants.... This problem appeared long before 27" iMacs came along and they still refuse to acknowledge it. The overheating is obvious but the panel sealing...

Maybe they didn't take in account that objects expand in the heat... I don't know...

And I think the sunny streaks on your iMac's display just show that the whole upper side of your display wasn't sealed properly and that the connectors acted like dust barriers. On other iMacs with dust problems the streaks don't appear.


So, we agree on one thing. The panel isn't sealed properly! I don't think that the way air flows has anything to do with it except that it causes extra heat. In the end: Hot air and dust have to go out and not inside the panel! That much is obvious.

And one more thing. I apologize in advance if I sound rude but maybe you are too technical for me. I had problems understanding what you meant with what you wrote. I had to read it three times to get it. I'm sure the guys at Apple had problems with it also, if they read it at all. And probably there lies a part of the answer why they didn't write back...

Maybe we can collect our experiences here and get somebody to write Apple some good guide for the next iMac generation.

Good luck on your further research!!!

Last edited by Oggy; Mar 27, 2012 at 02:12 PM.
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Old Mar 27, 2012, 04:15 PM   #155
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Hello Oggy, and thanks again for the pioneers role

First of all I want to thank you for your guide, I would not have dared to open a display housing without your thread. Now here in Germany there are following more and more people your guide. (MacUser-Forum)
And, ist clear, that I always cited your thread as the source of my skills.

http://www.macuser.de/forum/f7/braun...ml#post7371765

Second - my english is horrible, so sometimes we tend not to believe to people without good speech knowledge. But that would be a fault. I am definite not a technician, but an analyzer of certain scientific problems. And I tend to buy used iMacs on e-bay. So all the pictures are from my recent iMacs. This is a hobby, not more.

The PART II has the title: FROM HEAT PROBLEM TO PRESSURE PROBLEM.
In PART III I want to show the progress until the last 2011 27" iMac, which is said in one word: PRESSURE WALLS (of course also in former 27" iMacs.)



Let me outline the next:
You wrote:
"You haven't given us clue to why you think they did try to solve the sealing of the panels. Dust appears on 20", 24", 27" of all variants.... This problem appeared long before 27" iMacs came along and they still refuse to acknowledge it. The overheating is obvious but the panel sealing..."

First answer: They sealed here and there, but never completely tight.
They opened the upper exhaust slot a bit.
They made Aluminum-Backside, which contributes to cooling a bit.

I am not convinced, that the problem occurred already in the white iMacs.
Yes, there were bad problems with Phillips Displays in the 17"iMac 1,83 MHz Core Duo and maybe in the Core2Duo later. But I think they hat to do with the multi connectors, at least in one of ours. The display fainted segment for segment according the multiconectors. In that 17" the multi connectors were taped and so fixed to the frame, maybe they were unable to expand with the heat like the newer do in their slots. But I never saw dust traces in those 17".

The 20" Displays are of a more modern kind of construction, they are not sealed completely and they were built in an open frame.
I never heard of dust inside of them. Okay, that doesn't mean anything.
But the pressure-generating-design was incomplete and there was one more door open, like in all the white iMacs: The small gap between Frame and display prevents of to high pressure differences between upper and lower part.

I allways had the theory, but I don't know exactly, that first problems occurred with the glossy cover plastic front. At first, in iMacs from mid 2007 and early 2008 we got a different problem: The dust under the cover "glass". Thousands of threads fill the forums with happy Cover-glass-cleaners. The reason was: After generating the pressure difference in mid 2007 or around that the gap between frame and display, but under the cover "glass", remained open. There the air under upper high pressure had two ways back: Out into the gap under the cover "glass" or through the displays housing from top to bottom and out again.
Of course most of the air goes the way out through the upper exhaust slot, but not all.

I would go so far to say, that the problems were minimal in the open front iMacs and started with the closed glossy front.
Later in the 24" iMac from early 2009 I found a tight lip between frame and display to prevent the spoiling of the cover "glass". That in my opinion was the moment they closed the last door exept the display housing itself, which was now from the iMac early 2009 on was the victim of the air overflow.

Okay, many "clouds" in the displays look different from mine, but that does not speak against the multi-connectors-slot entrance-theory. Of course there may be other entrances. But all of them need to be situated in the upper part cause there is some pressure need to bring in air and dust... I was convinced that my iMac was a very dirty one. I bought it at e-bays with that fault and search in the web for inside-cleaners-giudes.
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Old Mar 28, 2012, 12:35 PM   #156
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PART III: Air flow in a new IMac as a result of many mechanical upgrades resulting in high pressure gradients: introducing THE PRESSURE WALL.
Air pressure's degree as a function of fan velocity (heat generating usage).
Displays pollution as a function of usage.

What is a pressure wall? There are 3 or 4 or 5 pieces of black plastics standing upright in the middle of the electronic parts to separate the low pressure side (green color) of the iMac from the high pressure side (red color). The pressure walls are essential to provide a controlled airflow and a sufficient cooling without short circuits and reheatings in the airflow.

But they divide the iMac into two parts, which are unfortunately bridged by the inner of the display housing, leading the air back to the low pressure side.
HERE AT FIRST THE PRESSURE WALLS (named so by Apple).







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Old Mar 29, 2012, 01:03 PM   #157
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Part iv: The airflow into the display

PART IV:

OGGY ASKED: „You haven't given us clue to why you think they did try to solve the sealing of the panels.“

My problem now is, that I am allways talking about the venting system of iMacs, where all readers want to see wholes and gaps in the construction of the display housing, more or less ignored by Apple and their suppliers.
It would be much easier to write simply: „The displays are unthight, a big mess and Apple doesn‘t care about it.“ But that‘s what you can read everywhere, formulas without arguments.

OGGY ANSWERED: „I don't think that the way air flows has anything to do with it except that it causes extra heat.“

Pardon Oggy, that‘s wrong. Airflow is able to take the heat from the electronic parts to the display, yes, but neighter it CAUSES the heat nor even hot vents are a temperature problem for a display panel.


APPLE TODAY CONTROLLS AIRFLOWS IN iMacs BY PRESSURE WALLS.
PRESSURE DIFFERENCES ARE RELEVANT BIG NOW, WHERE THEY WERE MINOR IN FORMER CONSTRUCTIONS
AIRFLOW FOLLOWS PRESSURES GRADIENT AND IT IS THE CARRIER OF THE DUST.
FORMER THE AIRFLOW WAS SLOWER, HOTTER, BUT WITH THE SAME LOAD OF DUST.

The primary problem of Apple iMacs was OVERHEATING. Lots of GPU-Chips deceased over the years.
With the „pressure Walls“ Apple solved this very serious problem and got the next one big problem. The construction of a transversal complete barrier through the middle of the machine left one very big structure (beside minor ones) out of consideration:

THE DISPLAY HOUSING IS THE LAST CHANNEL FROM HIGH TO LOW PRESSURES COMPARTMENT, FROM UPPER TO LOWER PART OF AN iMac.
WITH RISING PRESSURE DIFFERENCES THE AIRFLOW USES THIS CHANNEL IN A GREATER AMOUNT.

I will draw a graph of this situation.



And the Situation inside the display: THE MULTICONNECTORS-ENTRY-THEORY:






No, OGGY, the multi-"connectors acted NOT like dust barriers".

THE AIRFLOW TAKES AN U-TURN LIKE A ROLLERCOASTER UNDER THE MULTICONNECTORS, THE RAIL THROUGH THE SLOTS- THE BARRIERS ARE IN BETWEEN.

the End...

Last edited by Gebekophli; Mar 29, 2012 at 01:05 PM. Reason: One wrong picture
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Old Mar 29, 2012, 04:08 PM   #158
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Thank you for your engagement in this matter! I really love and appreciate it that somebody is out there willing to find out what is the problem with iMacs!


Quote:
Originally Posted by Gebekophli View Post
OGGY:„I don't think that the way air flows has anything to do with it except that it causes extra heat.“
A bit of misunderstanding here. I meant to say that the wrong airflow, which you elaborated earlier on the older iMac's, causes extra heat. And for that part you clearly shown us that Apple did something about it.

Quote:
Originally Posted by Gebekophli View Post
No, OGGY, the multi-"connectors acted NOT like dust barriers".

THE AIRFLOW TAKES AN U-TURN LIKE A ROLLERCOASTER UNDER THE MULTICONNECTORS, THE RAIL THROUGH THE SLOTS- THE BARRIERS ARE IN BETWEEN.
Ok! I stand corrected on this matter! You are right. The dust clearly is making a U turn beneath the connectors and they are not barriers.


In your graph, you drew that in the high pressure area air splits in two parts. One part goes out through the hole on the upper back side of the iMac and the other one goes inside the panel?

Where do you think it enters the panel exactly?


Oh I see it now! You drew it on the upper left corner of the picture of the electronic board.

http://imageshack.us/photo/my-images...onnectors.jpg/

So you think that air manages to enter under the electronic board of the display?

Last edited by Oggy; Mar 29, 2012 at 04:16 PM.
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Old Mar 29, 2012, 11:26 PM   #159
Gebekophli
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Thanks, Oggy, for your fairness and reviewing

Yes, only any part of the display in the range of the high pressure may be the entrance.

If you see taping anywhere along the sides from top till bottom you know, there was acting someone without isight of the problem

I can only speak for the iMac 24" from early 2009: There it was the partially unsealed lower edge of the cover tin over the displays electronic, which collected a small part of the airflow, cause behind this structure was the first place with low pressure again.

After that the air flows under the green electronic board, which is not glued to the back of the housing.

I did not wanted to draw two different airstreams, but I wanted to show, that the untight structure is not at the rim, not at the frame exept that slots of the multi connectors.
and two other gaps at the bottom, but they are on the low pressure side.

The multi connectors need that slots essentially, You never may glue them directly, otherwise that multi connectors may not move with warming up and cooling down after.

Before 2005 Phillips and LG fixed them with tapes and they broke off the board.

I am convinced they know, what happened at that time, cause they constructed the wider slots without taping.

THE WICKED GUY IN THIS GAME IS APPLE, NOT LG.
APPLE LOVES ITS FAR TOO SMALL EXIT VENT SLOTS
CAUSE OF DESIGN PURPOSES.

APPLE: MAKE THREE SLOTS THERE AND THE PROBLEM OF
DIRTY DISPLAYS IS FIXED.

Later I will show and commend the efford of LG at the backside of the display housing.

Oggy,thank you, and all the other readers, you are welcome to contribute you knowledge!
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Old Mar 30, 2012, 04:45 AM   #160
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This tin plate is similar on the 27" iMac.
On this picture the top of the display is closer to the camera.

http://forums.macrumors.com/attachme...0&d=1306956104

When you take the display out and turn it around there is some kind of sealing tape on this plate. But than it seemed to me that it's not important. I pealed it off and didn't put it back. And dust didn't return.


The multi connectors are on the upper side of the LED panel and they have no contact with the backlight in the 27" iMac. There is no space between LED and the backlight. The backlight has a foam band all around on which the LED panel "sits" on. This seals of the air between the LED and the backlight even in the area of the multi connectors.

Look for the gray line on the end of the bottom of backlight. It goes all around it.

http://forums.macrumors.com/attachme...8&d=1306956612


So, I'm still convinced that multi connectors and the displays logic board don't have anything to do with air coming in.



To put it simple: The LED panel seals of the space between it and backlight by itself.

I think that there are two possibilities:

1. The heat causes this foam seal to expand or get damaged and makes room for air and dust.

2. Transport of the iMac causes the LED (or the backlight) to get twisted or get misaligned (because it quite large) and creates a gap for air.

I'm sorry but you theory with high pressure and airflow comes actually to the same conclusion we have found out before. There is a gap between a LED and the backlight and the problem is sealing. Not airflow or high air pressure.

Last edited by Oggy; Mar 30, 2012 at 05:24 AM.
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Old Mar 30, 2012, 12:07 PM   #161
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Oggy, we don't have any problems with different opinions, we are talking about different displays.

1. I said, that I can only speak for the 24" iMac from 2009
I will show you more evidence of nicotine-traces on the inner side of the frame opposite the connectors slots.



And another potential entrance are the grooves of the left-side-situated-Layer connectors in the plastic frame:



So if you think, that the multiconnectors slots are not the entrance for the airflow, I will accept this for the 27" display, because everything is sealed there between TFT-panel and the first "light guide" plate. I didn't open the new display yet.

LG definitely worked on that problem. For me this sealing is not an argument against the multi connectors-entrance (in 24" from 2009), but the evidence, that they found this entrance and closed it. So, unfortunately, i'm a bit too late.
Now pictures of the 24" from 2006:




And now the 27" iMac 2011:



You are talking about a display of one of the 27" iMacs, please tell the year.
Your finding are impressive. When you speak about the LED, you mean the panel, but not the LED backlights? The right name is TFT LCD IPS (in plane switching) for the panel, but I had to look to Wikipedia.

I compared my 27" display from 2011 iMac and it looks a bit different from yours. You may compare the backside carefully, to find little differences.
My 27" display is named: LM270WQ1 (SD)(E3) Light Guide: PMMA
As you can see, there is far more black tape at the edge of the electronics cover.

You say the problem is sealing and not airflow or high air pressure.
Okay, I sealed and I hope the dust inside will never come again:



The theory of the consequences of high pressure and the need of sealing will not lead to the same conclusion, its related like hen and egg, but it has two different fathers: Once Apple is the addressee for the advice to lower the pressure, and twice LG should seal the displays focussed on the knowledge of the special micro-environmental conditions around the displays in iMacs.

You have to keep in mind, that the same displays work beautifully in the monitors without fans and high and low pressure, not only in Apple Monitors.

THE ONLY PROVOCATING THEORY OF MINE IS, THAT OPENING THE BACK SLOT, MAKING THREE OF THEM, COULD LOWER THE HIGH PRESSURE AGAIN, SO THERE WILL BE NO FORCE ANY MORE TO PRESS THE AIR THROUGH THE DISPLAYS

Did you really found out before that there is a high and low pressure compartment, that Apples airflow management is really ambitious and that it is really a hard work over years to embed this barrier inside of an primarily miss constructed system?
And, last but not least, that the LG-Display housing works as a tunnel or channel between them?

Do you really know until today, where the air is getting in, when it is not the multi connectors slot entrance? I don't know where the air went in, when I will have to clean the display in one or two years. May be after I know, May be I am too late as now with the 24" iMac from 2006

ONE BIG DEMAND TO EVERYBODY I HAVE: IF YOU ARE CLEANING YOUR DISPLAYS FOLLOWING OGGYS GUIDE; PLEASE MAKE PHOTOGRAPHS OF EVERY LITTLE DETAIL OF THE DUST AND THE FRAMES, THANK YOU

Last edited by Gebekophli; Mar 30, 2012 at 12:08 PM. Reason: Link to picture failed
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Old Mar 31, 2012, 12:44 PM   #162
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I'm shocked over this, I noticed the smudges today and thought a quick clean would suffice. I have my iMac in a clean room and as everyone has already said its a design fault as the mac design should be sufficient to work in a home environment.

I have a windows laptop that I use as a server on the floor and this would be more prone to dust but the LCD is fine!!

Now I have noticed it the screen looks awful and the smudges are literally all over the screen. When I read that apple blame customers for this as their environment must be toxic I'm amazed. My iMac is 15 months old and I brought it thinking the product was well made, how wrong was I.

This is my first mac, I've used, repaired, built pc for over 20 years as a hobby and I've never seen a problem like this of a manufacture wipe there hands of it. Surely there can be a claim in a court as the product is not fit for purpose
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Old Mar 31, 2012, 01:58 PM   #163
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Angry

I too am horrified by this problem. To add insult to injury when I reported this problem to the Apple Store where I bought my machine they said "it is not a known problem". When I then showed them there and then that 2 of the iMacs in their showroom had exactly the same problem they repeated the mantra! Pure Genius? No just plain stupid and arrogant. I will be pursuing this arrant nonsense - in the meantime I will not be buying any more iMacs and will be advising my clients to do the same.
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Old Mar 31, 2012, 02:19 PM   #164
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I have two iMacs that exhibit this smudging problem. Took them both for repair and the response of Apple that it is an "environment problem" caused by humidity and I should be more careful. That is just plain arrogant, WTF Apple stop escape goating and own up to what is obviously a awful DESIGN FLAW. Somebody should take a class action against them for faulty hardware. Faulty expensive hardware.
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Old Mar 31, 2012, 02:49 PM   #165
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Wow stumbling upon this thread has been a real surprise. Really making me second guess buying a new imac if so many people are having this problem.

I live in a home with two dogs and use a fireplace in the winter so dust and dander are natural here but we try to maintain a clean home as much as possible. Thinking an imac won't be a wise investment given all these problems, even with the most recent models.

Would a cover help? Or a mini fan blowing air away from the computer?

Apple Care or not, I live 2 hours away from the nearest Apple Store. It's a trip I don't want to make on a regular basis for something that seems to be a product defect.
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Old Mar 31, 2012, 09:30 PM   #166
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Quote:
Originally Posted by Jiten View Post
I have two iMacs that exhibit this smudging problem. Took them both for repair and the response of Apple that it is an "environment problem" caused by humidity and I should be more careful. That is just plain arrogant, WTF Apple stop escape goating and own up to what is obviously a awful DESIGN FLAW. Somebody should take a class action against them for faulty hardware. Faulty expensive hardware.
Mine was fixed by the Applestore... did they not swap out your panel?

I had the problem fixed a good 4 months ago now and the black spotting has not come back. Has it come back for anyone after a fix? I'm just curious.
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Old Mar 31, 2012, 10:07 PM   #167
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There is Hope for iMac 27" Display - Black Spots/Smudges/Dust in the display FIXED!

So far, I have talked to three Senior Advisors at Apple, a Apple Store Genius and his Manager.
The machine in question is a mid 2011 27” iMac. purchased in May of 2011 along with three year AppleCare.
All*Advisors*say this is my fault for having it in a toxic environment and there will be NO WARRANTY.
I guarantee that my home, I live alone, is a lot less toxic than the typical Apple Store with their wide open doors and huge crowds. Next time I am up to a trip out of town (at 80 years old I don’t usually drive far) to the Apple Store I’ll have to see how many of their iMacs have this “unknown” problem.
I do not smoke. No one has ever smoked in my home. Because of allergies, the house stays closed up and uses a premium air filter for the furnace.
Since I live outside of the 50 mile range I asked to have a technician visit my home and evaluate the situation. This request was ignored.
The latest from the last Senior Advisor is; Since the Apple Store refused to warranty it there will be NO warranty...
A friend suggested I take it to the Small Claims Court and sue Apple.
I emailed Tim Cook...
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Old Apr 1, 2012, 04:28 AM   #168
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Quote:
Originally Posted by MrXiro View Post
Mine was fixed by the Applestore... did they not swap out your panel?

I had the problem fixed a good 4 months ago now and the black spotting has not come back. Has it come back for anyone after a fix? I'm just curious.
I live in Singapore and it seems Apple folks are more accommodating in the US. I had to call Apple's Asia hotline first (and had to wait a week as my agent escalate this problem which took a week) before they finally agreed to exchange the panels. Big hassle. They also told me that this is the last time they will do that, if it happens again they won't exchange it anymore - as if the smudges were my fault.
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Old Apr 1, 2012, 06:05 AM   #169
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Join Date: Mar 2012
Location: Berlin-Germany
After all I still love iMacs...

First I have to confess that i'm a bit shocked about the deep emotional reactions. They may derived from the kind of managing the problem by Apple, making the customers guilty for this smudging-events inside the display-housings. I will tell you so far, that it's the same in Germany too. But the range of putative reasons seem to be a bit wider...
I will not comment this, cause I think Apples "Genius", and even "Advisor" personnel is completely misinformed and maltrained and they believe what they say.

I LOVE APPLE IMACS CAUSE I COULD FIX ALL THE PROBLEMS INSIDE BY MYSELF.

Second I have to correct two "years" in my last posting:
1. the third last picture is from an iMac 9.1 from 2009.
2. in the third last line the right Year is 2009.

PLEASE BE SO KIND AS TO ACCEPT, THAT BOTH COMPANIES, APPLE AND LG TRIED TO FIX THE PROBLEMS, BUT:

THE OVERHEAT PROBLEM, iniMacs from 2005 resulting in OVERHEATED CAPACITORS and in 2006 - 2008 built iMacs resulted in DAMAGED CPU-UNITS
HAD FIRST PRIORITY.
So Apple reconstructed the airflow and the cooling devices in the iMacs between 2006 and 2009 resulting higher airflow, generating a new, very insidious problem: The smudging of displays, because the airflow was rectified, which causes in a pressure difference between top (high) and bottom (low), and from 2009 on the display housing was the biggest open channel between high and low pressure compartment.
THe problem occurred according to my interpretation in those iMacs, which were used heavily, which doesn't mean the CPU-usage, but the GPU-usage, which is more to-the-heat-limit in iMacs. So professional photo-processing is not a problem like playing computer games. The measure of all is the resulting fan-speed. Sufficient pressure for display-intruding-air is only generated by high-revving fans. Thats the reason, why not everybody has the smudging problem. The so called Sissi-users have not.

Of course the problem was blamed on LG, and LG tried to do its best, but for a few more 27" iMac generations from 2009 till 2011 the best was not exactly the
applicable steps, the need steps. LG was tapping in the dark. But we are convinced, that there is a progress.
Apple, as far I can see, Apple has not put on the shoe, as we say in Germany, they do not see the airflow-corrections as a source of problem.

Steve Jobs said: "The problem is fixed". We all, owning iMacs form 2011, will see in the next years...

WHAT'S LEFT TO DO?
THE AIRFLOW-COOLING CORRECTIONS 2006 - 2011 ARE ESSENTIAL, BUT THEY HAVE TO GO ON: APPLE MUST OPEN THE AIR EXHAUST VENT SLOT OR MAKE THEM THREE TIMES. IMMEDIATELY THE PRESSURE WILL DECREASE, WHICH WILL RESULT IN AN AIRFLOW OUT AND TO GO NEVER AGAIN EVEN INTO AN UNTIGHT DISPLAY-HOUSING.

ONE THING IS VERY IMPORTANT: MY PICTURES SHOW CONSTRUCTION-EVENTS IN THE PAST, NOT IN THE PRESENT.

In the moment the situation is like someone (Apple) puts a unsuitable untight camera (LG_display) under water, blaming the manufacturer for failing after.
I'm not paid by Apple or LG...

Last edited by Gebekophli; Apr 2, 2012 at 10:26 PM. Reason: spelling mistake + some content + Steve
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Old Apr 1, 2012, 03:04 PM   #170
Oggy
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Join Date: Dec 2010
@Gebekophli,

dude, this thread is about 27" iMac's dusty display. As far as I understand you haven't opened one. So, although I admire your effort on the problem you have to open one 27" iMac and than we continue with the air pressure debate.

I still think you are wrong. If something is properly airtight than no dust can get inside.PERIOD!

And one more thing. If your theory was correct than all the iMacs would have dust inside the display. Well... they don't.

Last edited by Oggy; Apr 3, 2012 at 05:45 AM.
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Old Apr 2, 2012, 10:37 PM   #171
Gebekophli
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Join Date: Mar 2012
Location: Berlin-Germany
Why So unfriendly?

I've put some questions to you, Oggy.
Three quarter of the participants of this thread never opened any display, so what?
The chance of a forum is to collect knowledge, not more and not less.
I brought some information about the outer sealing of the 27" display to you to compare with your 27" display from 2009 or 2010.

You do not like to confess: Yes there seem to be efforts, even LG achieved.
We both even don't know, IF the problem of unthight displays is still the truth today.

Your mantra: UNTHTIGHT, UNTIGHT, UNTIGHT is no message of content.
We even don't know, how many displays were dirty and how many newly bought are still.

Why some dirty and the most not?
we don't know!
I speculated about heave usage with high fan speeds.
One heavy user replied: no problem.
Few light users replied: Problem!

That's it. We don't know.
Welcome, Oggy.
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Old Apr 3, 2012, 12:21 AM   #172
ravinder08
macrumors regular
 
Join Date: Jun 2010
Quote:
Originally Posted by rpoland View Post
So far, I have talked to three Senior Advisors at Apple, a Apple Store Genius and his Manager.
The machine in question is a mid 2011 27” iMac. purchased in May of 2011 along with three year AppleCare.
All*Advisors*say this is my fault for having it in a toxic environment and there will be NO WARRANTY.
I guarantee that my home, I live alone, is a lot less toxic than the typical Apple Store with their wide open doors and huge crowds. Next time I am up to a trip out of town (at 80 years old I don’t usually drive far) to the Apple Store I’ll have to see how many of their iMacs have this “unknown” problem.
I do not smoke. No one has ever smoked in my home. Because of allergies, the house stays closed up and uses a premium air filter for the furnace.
Since I live outside of the 50 mile range I asked to have a technician visit my home and evaluate the situation. This request was ignored.
The latest from the last Senior Advisor is; Since the Apple Store refused to warranty it there will be NO warranty...
A friend suggested I take it to the Small Claims Court and sue Apple.
I emailed Tim Cook...
I have a 2010 i7 Imac 27".
I had the same problem noticed grey marks and phoned apple care they said no problem and replaced the lcd free of charge. The guy at the store said he's had a few machines in with same problem. I would try ringing apple care again and maybe point them to apple discussion board on there website where the problem is commonly reported.
__________________
Late 2012 27" iMac, 3.4 GHz Intel Core i7, 8 GB RAM, 1TB HD, NVIDIA GeForce GTX 675MX 1024 MB
iPhone 5 16GB Black, iPhone 4 S⃣ 16G Black, iPad AIR 32gb white.
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Old Apr 3, 2012, 12:23 PM   #173
Oggy
Thread Starter
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Join Date: Dec 2010
Quote:
Originally Posted by Gebekophli View Post
We don't know.
Welcome, Oggy.
We know! There is dust inside my display! It didn't get there by teleporting!

Please stop trolling!
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Old Apr 3, 2012, 04:01 PM   #174
All Taken
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Join Date: Dec 2009
Location: UK
Whats with all the talk of airflow? I mean, sure, it places the dust on the scree, however, the actual reason for dust on the screen is that the surrounding soft foam designed to make contact with the glass display housing is insufficient in a lot of circumstances.

It does not always make contact the whole way around meaning gaps are present either width or perimeter wise.

Simple really, my best guess would be that whichever cleaning solution the factory use during production of these panels reacts to heat from the display, causing 'smudges'.

The gaps in the foam panel to glass display housing are more than likely present to help dissipate heat from the otherwise enclosed area immediately inside the foam sealed area, a otherwise great solution to a heating issue but poor in terms of sealing from dust.
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Old Apr 4, 2012, 07:17 AM   #175
notme
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Join Date: Mar 2003
imac 21" grey smudges

Hello,

I bought my 21" iMac in Jan 2011, I discovered the grey stains some weeks ago (upper right corner), they became bigger last 2 weeks. I am in Europe, have 2 years of warranty from the seller, but don't know if I will have to fight for a LCD replacement :S Apple doesn't care after 1 year, and don't have Apple Care.

I tried first to clean the glass, took it out, also cleaned LCD, but was clean. Stains are inside, or like you say, between LCD and backlight.

But is this a dust problem or LCD burnt because of HEAT? I read people speaking about using smcFanControl... and I am confused. My LCD can be cleanned being dust, or replaced being heat burnt?

When putting the glass back I saw that it seems I scratched a corner a bit, see the pic attached, I used the flash to be able to capture it. In real life is much more difficult to see, BUT I think that if you are very into detail, you can notice it. Removing the glass voids the warranty?

I am afraid that they tell me they don't replace the LCD because of removing it.
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Last edited by notme; Apr 4, 2012 at 08:14 AM.
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