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Kaos2K Author

Level 1

1 points

[GUIDE] Fix iMac flickering and dark screen problems out of warranty

If you have a Late 2009 27" iMac and are having problems with those annoying problems of flickering and parts of your screen are becoming darker (On the left side primary) you may want to consider this easy guide to fix it if you run out of warranty, have no Apple Care and Apple wanted to charge you about $600 to replace your screen. You need no tools and the cost os this procedure is 0.

First Step: Be sure that you are experiencing the same symptoms

This guide is only to resolve flickering and dimming problems on you iMac screen. Primary occurring on the left side (becoming darker or with less brightness than the other side) and on Late 2009 27" iMacs but there are cases of the same problem on later computers too.

Check/Read all of these posts to know if your case is the same:

Thanks to the findings of nicholasfromconfolens we know that the problem resides in some parts of the screen getting loose for any reason (factory problem, heat, whatever) and if you apply pressure at certain point the flickering/dimming/darking disappears. The problem is that you need to maintain that pressure all the time.

Second Step: Find the correct spot to apply pressure

Without removing the glass panel of the iMac, try to press it strong enough (but don't use excessive force or you could break it) near the bottom left part to see if the dark/flickering disappears at some point. If it does, you are lucky, your problem has easy solution and you can proceed to the next step. If not, don't despair, your glass panel may be very strong and you will need to remove it to apply pressure. Head to the next step.

Third Step: Removing the glass panel

It is recommended to use suction cups to make this task more easily but it's not mandatory, you can remove the glass with your hands. The glass panel uses magnets to get in place all around and has some flaps on the bottom part. To remove it you need to hold it from the upper right and left corners and make force towards you, once it get loose just elevate it to remove the bottom flaps from its holes. You can follow these links with guides that clarifies this a bit more:

Fourth Step: Pinpoint the correct spot to press and place something to maintain the pressure

Once the glass panel has been removed, you must find where is the best point to apply pressure to get rid of the dimming/darking/flickering. The most common point is the left side between the rubber band of the screen and the grey band below. (See the photos for better understanding).

Once you find the best spot, you need to place there something to increase the thickness in that point and to maintain pressure when the glass panel is mounted again. I suggest you to use a pair of adhesive strips/pads mounted one over the other made of rubber or textile material that are used to put under furniture (chairs, tables) to prevent them to scratch the floor (I don't know the exact name in English, sorry).

Fifth Step: Mount the glass panel again

Mount the glass panel again and see if the pressure is enough to prevent the problem appearing again. If not, you should dismount the glass panel again and add more thickness to the "critical" spot adding more pads, but beware, add them gradually or the pressure may be excessive and break the glass when you remount it.

Final Step:

Enjoy your "new" screen and the saving of nearly $600 on repair costs.

Here below you can fin some photos and a video of my "set-up" to fix the problem.

iMac 27" (Late 2009) Flickering And Dark Screen Fix (VIDEO)

I hope this guide helps you. Feel free to contact me if you have any questions.

iMac, Mac OS X (10.6.4), No tools required

Posted on Jun 19, 2012 8:37 AM

186 replies

Apr 12, 2015 4:03 PM in response to Kaos2K

Ok, i can confirm that this is mostly the same issue as with the LED Cinema Displays MDP/Thunderbolt when having flickering and/or no backlight at all, since they got the same old crappy LG Panel inside as the iMac. So first of all, the Cinema Displays show different symptoms than the iMac because of the Logicboard that shuts off both LED strips when one of them fails. In my case (Cinema Display 27 inch MDP) it was the bottom right connector which had minimum three disconnected/unsoldered pins. So i took the whole display apart and resoldered the connector. You should definitely get yourself some thin rubber gloves and an air compressor to get rid of the dust when reassembling this piece of… Anyway, the symptoms i had was that i had to first plug the upstream USB and MDP cable and then replug the power cord a few times before the flickering turned into a working backlight. Sometimes it was working for 10 Minutes and sometimes even for more than five hours, depending on the room's temperature. After checking Voltage of the Logicboard and Power Supply (also transistors and caps) i thought it can only be the LED section, and after finding this thread i knew it for sure. So, nice finding Kaos2K!!!

After having so much problems with these **** LG panels, i'm asking myself why in **** does apple still use them for their products? Even the current Thunderbolt displays got these panels inside. A question apple will probably never answer, huh?

Renko85

Level 1

0 points

Jun 22, 2015 1:17 AM in response to Kaos2K

I was able to correct the problem by soldering the connector, as mentioned bij Kaos2K on Jun 22, 2012 11:44 AM. It works like the original iMac again!

PiGiH

Level 1

0 points

Sep 8, 2015 10:29 AM in response to Kaos2K

Hi to all,
I've just experienced the darker side problem on my 2011 imac 27", and I've seen that pressing on the glass it become brighter. So I'll try to fix it as you suggested 😉.
But in the last two months, my mac showed another problem: the display turns black(also many times in a day), and I've to sleep-unsleep my mac to see it again. While the display is black I can continue to listen music, and lighting it with a light, I can see all my stuff. So The mac is still running.

My question is:

Are the two problems related?,
or is the second caused by a fault LED driver board?

thank you.

and sorry for my bad english😊

Jan 26, 2016 12:49 AM in response to PiGiH

We have seen this problem at www.werepairtech.co.uk and have fixed it

May 17, 2016 11:10 AM in response to WeRepairTech ltd

I've had some smudging issues in the lower lh area of my mid 2010 27" iMac for some time.

I just assumed it was dust under the glass and hadn't gotten around to removing the glass to clean it until today.

But these smudges are not from dust.

Unlike the majority of people in this thread, my issue does not involve a mass darkening of most of the lh side of the LCD.

I've attached a jpeg that shows the smudges that I have which look more like one of Hubble's pics of a star-forming gas cloud on the lower lh side of the screen. lol

[Note: Most of the other weird looking round shaped smudges in this pic seem to be related to screen reflections caught by the camera and in fact are not an issue.]

Can anybody confirm if my smudges are due to the same bad connector that is being discussed in this thread?

I don't think I have the soldering chops or tools to resolder the wires, ala Kaos' method.

But I think I could probably manage to lift up the bottom of the LCD enough to try jiggling the jack as suggested by John-
Paul.

But I don't want to bother with it unless there's a high likelihood that my issue will be fixed by doing this.

What do you think?

This whole thing is pretty lame on Apple's part.

In my case, this mid-2010 27" iMac was given to me free of charge by an Apple store up here in Toronto when the 2009 24" iMac I had actually bought a year earlier began to show dark spots that I assumed were just bad pixels.

The Geniuses told me that the 24" iMac's screen could not be repaired or replaced so they gave me the 27" iMac as a replacement even though my 2009 was past its warranty expiration.

I was pretty pleased about it all at the time.

But now i don't know what to think.

Glad I don't do a lot of hi-end graphics work on this machine.

May 23, 2016 11:57 AM in response to Joey Goldstein

Anybody out there?

[GUIDE] Fix iMac flickering and dark screen problems out of warranty