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Current version by: mayer (vote details) ,

Title:

Backlight randomly turning off

Text:

iMac Intel 27" EMC 2374

Hi, i have very annoying problem with my 27" late 2009 iMac (MB953LL/A), that have been mentioned here few times already, but nothing seems to help. Basically the problem is that my screen backlight goes black from time to time (i still see content behind black screen with flashlight), it can be fine for a day and next day it can turn off 50 times per hour. After i put display to a sleep and wake it, it starts working fine again.

I've read here that someone solved the problem by changing V-Sync cable, i ordered one, changed, but that didn't helped

The next thought was about overheating, so we cleaned everything from dust and removed heat sensor from screen and just sticked it on SSD, we also removed V-Sync cable completely. But the problem is still there.

I had this problem on a completely cold computer that was waken up after night.

Any further ideas or recommendations? Thanks.

== Update ==

Just heads up regarding problem.

After i detached led temp sensor from screen, it’s been more than 2 weeks without single blackout. So i don’t think that the problem is in LED driver board. I have new problem just right after removing vsync cable and led temp sensor: The screens blinks (dims) once in a 5 minutes randomly, to be more clear i made a gif: http://i.imgur.com/zUXXFvK.gif. This problem is somehow related to V-Sync cable or this might be more serious problem?

Device:

iMac Intel 27" EMC 2309 and 2374

Status:

open

Accepted Answer:

223963

Edit by: Taps ,

Title:

Backlight randomly turning off

Text:

iMac Intel 27" EMC 2374
 
Hi, i have very annoying problem with my 27" late 2009 iMac (MB953LL/A), that have been mentioned here few times already, but nothing seems to help. Basically the problem is that my screen backlight goes black from time to time (i still see content behind black screen with flashlight), it can be fine for a day and next day it can turn off 50 times per hour. After i put display to a sleep and wake it, it starts working fine again.
 
I've read here that someone solved the problem by changing V-Sync cable, i ordered one, changed, but that didn't helped
 
The next thought was about overheating, so we cleaned everything from dust and removed heat sensor from screen and just sticked it on SSD, we also removed V-Sync cable completely. But the problem is still there.
 
I had this problem on a completely cold computer that was waken up after night.
 
Any further ideas or recommendations? Thanks.
 
== Update ==
 
Just heads up regarding problem.
 
After i detached led temp sensor from screen, it’s been more than 2 weeks without single blackout. So i don’t think that the problem is in LED driver board. I have new problem just right after removing vsync cable and led temp sensor: The screens blinks (dims) once in a 5 minutes randomly, to be more clear i made a gif: http://i.imgur.com/zUXXFvK.gif. This problem is somehow related to V-Sync cable or this might be more serious problem?

Device:

iMac Intel 27" EMC 2309 and 2374

Status:

open

Edit by: Dan ,

Title:

Backlight randomly turning off

Text:

iMac Intel 27" EMC 2374
 
Hi, i have very annoying problem with my 27" late 2009 iMac (MB953LL/A), that have been mentioned here few times already, but nothing seems to help. Basically the problem is that my screen backlight goes black from time to time (i still see content behind black screen with flashlight), it can be fine for a day and next day it can turn off 50 times per hour. After i put display to a sleep and wake it, it starts working fine again.
 
I've read here that someone solved the problem by changing V-Sync cable, i ordered one, changed, but that didn't helped
 
The next thought was about overheating, so we cleaned everything from dust and removed heat sensor from screen and just sticked it on SSD, we also removed V-Sync cable completely. But the problem is still there.
 
I had this problem on a completely cold computer that was waken up after night.
 
Any further ideas or recommendations? Thanks.

Device:

iMac Intel 27" EMC 2309 and 2374
iMac Intel 27" EMC 2309 and 2374

Status:

open

Edit by: Taps ,

Title:

Backlight randomly turning off

Text:

Hi, i have very annoying problem with my 27" late 2009 iMac (MB953LL/A), that have been mentioned here few times already, but nothing seems to help. Basically the problem is that my screen backlight goes black from time to time (i still see content behind black screen with flashlight), it can be fine for a day and next day it can turn off 50 times per hour. After i put display to a sleep and wake it, it starts working fine again.
 
I've read here that someone solved the problem by changing V-Sync cable, i ordered one, changed, but that didn't helped
 
The next thought was about overheating, so we cleaned everything from dust and removed heat sensor from screen and just sticked it toon SSD, we also removed V-Sync cable completely. But the problem is still there.
The next thought was about overheating, so we cleaned everything from dust and removed heat sensor from screen and just sticked it toon SSD, we also removed V-Sync cable completely. But the problem is still there.
 
I had this problem on a completely cold computer that was waken up after night.
 
Any further ideas or recommendations? Thanks.

Device:

iMac Intel 27" EMC 2374

Status:

open

Edit by: Taps ,

Title:

Backlight randomly turning off

Text:

Hi, i have very annoying problem with my 27" late 2009 iMac (MB953LL/A), that have been mentioned here few times already, but nothing seems to help. Basically the problem is that my screen backlight goes black from time to timetime (i still see content behind black screen with flashlight), it can be fine for a day and next day it can turn off 50 times per hour. After i put display to a sleep and wake it, it starts working fine again.
Hi, i have very annoying problem with my 27" late 2009 iMac (MB953LL/A), that have been mentioned here few times already, but nothing seems to help. Basically the problem is that my screen backlight goes black from time to timetime (i still see content behind black screen with flashlight), it can be fine for a day and next day it can turn off 50 times per hour. After i put display to a sleep and wake it, it starts working fine again.
 
I've read here that someone solved the problem by changing V-Sync cable, i ordered one, changed, but that didn't helped
 
The next thought was about overheating, so we cleaned everything from dust and removed heat sensor from screen and just sticked it to SSD, we also removed V-Sync cable completely. But the problem is still there.
 
I had this problem on a completely cold computer that was waken up after night.
 
Any further ideas or recommendations? Thanks.

Device:

iMac Intel 27" EMC 2374

Status:

open

Edit by: Taps ,

Title:

Backlight randomly turning off

Text:

Hi, i have very annoying problem with my 27" late 2009 iMac (MB953LL/A), that have been mentioned here few times already, but nothing seems to help. BasicalyBasically the problem is that my screen backlight goes black from time to time, it can be fine for a day and next day it can turn off 50 times per hour. After i put display to a sleep and wake it, it starts working fine again.
Hi, i have very annoying problem with my 27" late 2009 iMac (MB953LL/A), that have been mentioned here few times already, but nothing seems to help. BasicalyBasically the problem is that my screen backlight goes black from time to time, it can be fine for a day and next day it can turn off 50 times per hour. After i put display to a sleep and wake it, it starts working fine again.
 
I've read here that someone solved the problem by changing V-Sync cable, i ordered one, changed, but that didn't helped
 
The next thought was about overheating, so we cleaned everything from dust and removed heat sensor from screen and just sticked it to SSD, we also removed V-Sync cable completely. But the problem is still there.
 
I had this problem on a completely cold computer that was waken up after night.
 
Any further ideas or recommendations? Thanks.

Device:

iMac Intel 27" EMC 2374

Status:

open

Original post by: Taps ,

Title:

Backlight randomly turning off

Text:

Hi, i have very annoying problem with my 27" late 2009 iMac (MB953LL/A), that have been mentioned here few times already, but nothing seems to help. Basicaly the problem is that my screen backlight goes black from time to time, it can be fine for a day and next day it can turn off 50 times per hour. After i put display to a sleep and wake it, it starts working fine again.

I've read here that someone solved the problem by changing V-Sync cable, i ordered one, changed, but that didn't helped

The next thought was about overheating, so we cleaned everything from dust and removed heat sensor from screen and just sticked it to SSD, we also removed V-Sync cable completely. But the problem is still there.

I had this problem on a completely cold computer that was waken up after night.

Any further ideas or recommendations? Thanks.

Device:

iMac Intel 27" EMC 2374

Status:

open