I hear ya, my biggest concern is getting a screen with dead pixels. This is my second machine, I sent the first one back within 14 days to B&H for replacement because of a dead pixel right in the middle of the screen. So if the screen has to be replaced, I'm gonna call and ask them to really check the display before I drive out there to pick it up.
Just wanted to add to the list: I have i7, 2011 iMac, and LEFT side of the screen is dim. Started with flickering. Btw: I've also had a logic board replaced. Now it's back to the shop for a new display. Seems as if the engineering on this model is not the best? I'm beginning to hope Apple has a recall on this.
I also wish to add to the list: I have an iMac 27" 2011 which I purchased in April although I did not start using until June. My screen started flickering initially and now the bottom left of screen is dark. I reported it before Christmas to my retailer and as I have a 2 yr warranty have to take it in for repair but as it is a 50 mile round trip into Edinburgh I have not yet managed to take it in. I am dissapointed that this happened as the reason I bought a Mac is that I thought it would be trouble free as I had moved from Sony as I had a similar problem with them only my computer was just out of warranty and it was going to cost more for the back light to be repaired than the cost of a new machine.Hopefully it will all be sorted but it is definately a design problem with the Thunderbolt display.
HEAT is the cause!
I have a 2.8 GHz i5 27" iMac since one and a half year and had the same problems:
- at startup everything okay;
- after about 5-10 minutes some flickering and darkning of the left side of the screen.
A friend of mine suggested that this could be a heat problem.
After opening the iMac, it seemed to me that is was quite ingenious in how it dissipates the heat from CPU and GPU. After one and a half year of use, the blades of all three fans contained a steady amount of dust and the heat sinks were partially covered/blocked with dust.
Cleaning everything made my iMac work as before.
My conclusion afther this exercise is that, while there was to little throuput of cooling air, either the LED driver board or the power supply heated up to much and started to malfunction.
FOUND THE CAUSE!!!!
Hi everyone, Ok I have the flickering screen followed by dim lower left screen. This gets darker. The screen recovers if left in standby or turned off for a whilst!!
Ok so the machine is out of warranty. I removed the glass and screen and cleaned everything ..thinking dust build-up could produce thermal problems.
Put it back together ...guess what same problem!!!!!
I found that if I pressed the aluminum cabinet under the darkened area of the screen the screen returned to full brightness...SOOO I removed the glass again and found that if I wedged a piece of card or plastic between the screen lower left edge and the Aluminum frame the problem disappeared. Replaced glass and hey presto!!
I must say that it is so obvious that this is a manufacturing fault of the lg screen. Why don't Apple come clean and admit that there is/was/still is a problem!!!!!!!!!!!!
I am disgusted that a company with the prestige of apple will not sort this out.
Not sure how to take this further!!!!
With all the mounting evidence you would hope/expect a supposedly reputable company would deal with it.
I spoke with apple care yesterday and they flattly refused to acknowledge that these screens were giving problems
Infact said he had not seen any evidence of problems like this on the forums. Incidentally ... I assume that by squeezing the panel in the lower left corner to cure the problem I am in fact pushing some contact together to reconnect the back light led's in that area?? Hope it Does not get worse!!!
Come on apple don't let a duff panel from lg ruin your good name!!
(deaf ears) you reckon!!!!
nicholasfromconfolens said thank you so much for this post.
nicholasfromconfolens said: " ... wedged a piece of card or plastic between the screen lower left edge and the Aluminum frame the problem disappeared. Replaced glass and hey presto!!"
My problem, I don't quite understand WHERE you were applying pressure. If possible perhaps you could please look at my large image here ....
detailed image: http://postimage.org/image/r5lqglbo5/
see what you think! Thanks a million, nicholasfromconfolens !
I'm trying to figure out just WHERE to apply the pressure. I fiddled with it for a long time and at one magic moment I found the point to press, but I was drunk so I lost track. I'm not sure if you meant the piece of plastic is vertical or horizontal.
If you get a chance to look at my image, thanks a million.
This is a huge annoying problem on these screens. You can't pay $1000 to fix a $3000 machine. Horrible!
Hello John-Paul, The pressure needs to be put bottom left corner 1" in on the mysterious grey strip. I have changed the way I do it now because the previous way was unreliable. I now have the fascia glass screen removed on a permanent basis. this enables me to place something to spread the load along the gray strip from the corner (about 3" long) and place a small clamp applying pressure onto the strip...(more than you could apply with your fingers). The screen has been bright and free from dimming for 3 weeks now. If I remove the clamp the screen immediatly goes DIM again. It is a bit of a heath robinson approach ..but it works..and I can carry on with the editing of my photo's again without the distraction of the dimming and flickering screen....I am still fuming and disgusted at the total lack of response from APPLE the way they have ditched us with these poorly manufactured screens.
I am going to produce a video and put it on YOUTUBE over the next few days...1. To help people affected with these screens to hopefully get some sort of a remedy. ..2. To highlight the disgusting apathy paid to loyal customers by APPLE !!
Nicholas - thank you VERY MUCH fo rthe detailed directions to the spot that worked for you. Thanks.
I am intrigued that it is the MGS*, I'm glad I asked as I incorrectly assumed you meant somewhere else.
Great stuff - thanks - thanks a millions.
I will now give it some attempts based on that.
If that doesn't work, I'm going to rip off the MGS, or saw off a corner of the display unit's metal case, and see what the heck I find in theren that area.
Incidnetally: Have you (or anyone reading) taken your display right out of the machine? I find that it is very easy to disconnect the two data cables. And it's possible to disconnect on the mac side the annoying very small "sync" cable to your right near you when you tiit the screen up (obviously after unscrewing the eight holder screws) - if you fool around with it a bit and just keep trying with your fingernails. However I have never been able to get off the temperature sensor cable from either at the mac end of that cable or the display-unit end of that cable. (The small cable that is deep inside, slightly to the left, when you tilt up the screen.)
To swap the HD, I simply leave in the mentioned heat-sensor cable, propping up the display unit at an angle. (You need something the exact size to prop up the display unit ... fortunately, an object the exact size is: an iPad! Heh!) However for serious work on the display-unit, I'd like to detach that temp sensor cable, and hence lift out the display-unit and sit it on the floor separately. But I've not been able to get that one cable out, on either the mac side or the display side (where it's sort of glued on with some gunk, it seems), and I haven't found any detailed "how-to" instructions specifically regarding that cable. So that's a slight hold-up if you want the display-unit out. (I guess an ultimate solution is to buy a new display-unit ... well over $1000.)
THANKS AGAIN !!!!!!! Will look for the utube vid.
*MGS. Mysterious Gray Strip