Lower Half of iMac screen dim

Question

Lower Half of iMac screen dim

This past week, the lower half of my iMac 24 started to intermittently go dim. Sometimes it fixes itself on restart, sometimes it doesn't. Sometimes it just goes back to working correctly. This is a 2.8 core 2 and I'm running 10.5.8 My 1 year warranty ran out in September (first time I've had a problem and I've been an Apple user since 1982).
I'm posting a video of the startup (taken from my iPhone) to give those interested an idea of the problem.
You'll see in the video the screen starts up normal then almost instantly goes half dim.
Sometimes it doesn't give me a problem- it was fine all day Saturday but now it's back.

http://gallery.me.com/kevindjones/100026/iMac%20dim%20screen
Thank for your advice-

iMac 24 2.8, Mac OS X (10.5.8)

Posted on Nov 15, 2009 3:55 PM

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Answer 1

Nov 23, 2009 4:47 PM in response to proximityeffect

So, this condition has become permanent. I guess I'll call Apple Tuesday.

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Answer 2

aijemc

Level 1

8 points

Nov 27, 2009 12:36 AM in response to proximityeffect

The same thing just happened to my iMac today, but the upper side of the screen is the one that's dimmed out.

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Answer 3

drjhunt

Level 1

0 points

Nov 29, 2009 8:59 AM in response to proximityeffect

Hi,
May I ask, did you ever resolve this problem? It has just started to happen to me, exactly the same. I'm also out of warranty. Any help gratefully received.

James

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Answer 4

aijemc

Level 1

8 points

Dec 1, 2009 3:56 PM in response to drjhunt

Yes I did fortunately my iMac was under warranty, and the guy came over to my place and fixed it. It seems that the LCD backlight is just gone. That's all he changed the LCD on it and now it's normal.

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Answer 5

aijemc

Level 1

8 points

Dec 1, 2009 4:45 PM in response to drjhunt

Unfortunately now the ambient fan seems to be blowing harder and harder, something that it didn't do before. I was looking at iFixit and saw that the screen has two sets of T8 screws the top left and right screws are 13mm T8 and the bottom 4 are 25mm T8. When the tech took the computer apart he put them all in one pile and then started grabbing them at random and putting them back. This is I think is causing the MXM plates not to touch and causes the ambient fan to start going and going. The RPM just keeps rising. At boot time the GPU is between 33-35 degrees Celsius. I called him and he'll back thursday with a new sensor and ambient fan? Oh well it's under warranty.

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Answer 6

aijemc

Level 1

8 points

Dec 2, 2009 9:19 AM in response to aijemc

Oh my gosh does Apple just hire who ever? After running the AHT test it seems that problem that is causing my iMac's cpu fan to run at high speed is the fact the LCD sensor may not be connected to the MLB or is damaged. I emailed the tech with this heads up and the error code (4SNS/1/40000000:TLOP) and he answered me that he has ordered a new video card now, ***, oh well it's under warranty and I would like to see how far this goes. The guy is really nice but I don't think he has a clue of what is going on.

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Answer 7

aijemc

Level 1

8 points

Dec 9, 2009 4:19 PM in response to aijemc

New video card has been installed but full RPM fan problem still persists. Now the logic board is coming, we'll see how that works.

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Answer 8

aijemc

Level 1

8 points

Dec 20, 2009 1:36 AM in response to aijemc

Well for anyone who has been following my saga regarding my 24" iMac early 2009 desktop going from a simple LCD replacement to a video card and now logic board being replaced because of the CPU fan blowing out at 100% something it never did before, the end of the story is with Apple now exchanging the computer for a 27" iMac which now means that I have to purchase a new desk and possibly go through all the stuff that happened with my 24" computer because from posts I'm reading the 27" iMacs are not in good shape to begin with. I really really want a 24" computer, but Apple doesn't make them anymore....:(

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Answer 9

Jan 6, 2010 8:55 AM in response to proximityeffect

In my case- the LCD panel has to be replaced. This is a cost of $600 out of my pocket with labor. Bottom line- purchase Applecare with your iMacs and laptops.

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Answer 10

Jan 15, 2010 11:41 PM in response to proximityeffect

I have the same problem. Upper half of the screen. Has anyone been able to identify the specific part that needs to be replaced?

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