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Level 1

6 points

Backlight turns on and off randomly

Hi,

I have an extremely annoying issue with my original 13" MacBook. Basically, at random times the backlight shuts offs as if the computer is going to sleep. Sometimes, it can be fixed (temporary) by shutting the lid and opening it again, as if the computer is waking up from sleep. There seems to be no obvious way to reproduce this problem – sometimes I go for an hour or more without it, sometimes it happens ever 10 seconds and the computer is unusable.

So far, I've tried resetting the PRAM and the SMC – no effect.

Any ideas to fix this would be greatly appreciated.

Macbook (late 2006), Mac OS X (10.6.4)

Posted on Jul 28, 2010 4:42 PM

Best reply

sirfaba

Level 3

610 points

Posted on Jul 28, 2010 6:27 PM

Could be from a bad connection between the MLB and the display. The MLB (main logic board) and integrated graphics may be going bad. Or your backlight may be going out.

Does this happen when you tilt the screen back and forth?
Any vertical or horizontal lines appearing at any time?

View in context

25 replies

Mar 7, 2011 1:40 AM in response to Vannuch

after extensive research i was convinced the inverter was broken and had to be exchanged. however, that didnt do the job, turned out that i had to get a new screen, now everythings working fine again

Mar 7, 2011 2:46 PM in response to sammycw124

Where'd you get a screen from and how much if you don't mind me asking?

Mar 7, 2011 2:52 PM in response to markbrooke

i had it repaired at justcom in hamburg, germany. it cost me 170 euros (240 USD). otherwise you can always buy a screen on ebay and try to do it yourself. they have instructions how to do that on ifixit.com

Will___

Level 1

15 points

Mar 9, 2011 7:01 PM in response to rhombus

Hi this is exactly what is just starting to happen to me.
If I keep brightness at 1 bar, then it is fine.
2 bars is fine for long extended time, but at times I can still lose backlight,
anything 3 and beyond won't last much time.
and when it goes off, I either just have to turn brightness all the way down, and back or to black out my screen and wake it up to turn in on again.
Not too sure what is wrong with it either. But it seems like at some times, vibration can also contribute to the issue as well (very rarely though, happened clearly 2 or 3 times only)

has anyone went through apple with it (within or out of warranty), and what are the responses?

thanks! I am hoping that I wont need to throw in anymore money for this machine... (basically all parts had been replaced besides the outer casing...)

oh by the way, another possible clue. this only started a week after I had my topcase and screen boarder replaced

TXANKLAS

Level 1

0 points

Oct 16, 2011 11:43 AM in response to rhombus

TO MY FEEL EXACTLY THE SAME,

WITH A MBP 15 "SCREEN BLACK, WILL NOT TURN THE APPLE ON THE BACK, IN RETURN, THE FANS AND THE HARD DRIVE IF THEY PULL THE PROBLEM IS NOT SEE ANYTHING, COMPLETELY BLACK

I CAN DO?

aaalex

Level 1

0 points

Dec 3, 2011 12:48 PM in response to rhombus

hi folks, exact same issue, backlight goes of when it feels like it, close lid and reopen and it works ok for a while, put in to mac specialist who tried replacing the inverter, inverter cable and screen, guess what, same problem still there, they suspect logic board fault?? any ideas anyone, on a positive as it wasnt repaired there was no charge for there services, how good were they.

mbmsv

Level 1

0 points

Jan 24, 2012 12:08 PM in response to rhombus

Hi all,

One more with the same problem. Tried replacing inverter to no avail. The external monitor works fine. Does it reliably say that I need to replace the screen or is there still something else?

Thanks.

Apr 22, 2012 5:23 AM in response to Will___

Hi Will, hi all,

Will wrote:

Hi this is exactly what is just starting to happen to me.

If I keep brightness at 1 bar, then it is fine.

2 bars is fine for long extended time, but at times I can still lose backlight,

anything 3 and beyond won't last much time.

and when it goes off, I either just have to turn brightness all the way down, and back or to black out my screen and wake it up to turn in on again.

Not too sure what is wrong with it either. But it seems like at some times, vibration can also contribute to the issue as well (very rarely though, happened clearly 2 or 3 times only)

I have the same problem as exactly described above:

Display don't take much background light.

Changed inverter already (a used one). It can't be the invertercable because i don't move the macbook or its lid if it happens. Don't want to replace the display if logic board is out of funcion.

Is it display bulb or not?

Such a common problem / diagnostic should be cleared easily ???

Vortico

Level 1

0 points

Apr 25, 2012 3:18 AM in response to rhombus

This is happening to me as well. I recently connected my Macbook to an external display, and my internal monitor backlight started cutting off a few days later. I can usually fix this momentarily by switching off and on the backlight with the Fn-keys, but it has become increasingly difficult to do so.

When the backlight is finally on, I can clearly shut it off by lightly shaking the display, so it's definitely a hardware issue with the bulb, logic board, or cable between the two.

Apr 25, 2012 5:07 AM in response to erdaleke1

I read in german version of Wikipedia that CCFLs are going to loose power and to clear this problem the producers implement a stabilizator between the bulb and system (Maybe integrated in the inverter). Wikipedia writes additionally that the backlight may turn off suddenly and completely if the bulb is weakend that much that the stabilizator no deliver enaugh power to the bulb. After some times the stabilaizator recovers and delivers its power. This issue happens less, if you set the backlight low i.e. bulb is defect.

Backlight turns on and off randomly