MacBook Screen/Backlight

[timsutcliffe]

A month or so ago, the backlight randomly went out on our MacBook. If you look very closely you can see the screen, but it's like you've got the brightness on its lowest setting. The backlight comes on as normal when you turn on the computer, or wake it from sleep, but goes out after about 2 minutes. Other than not being able to see what's going on, the computer works fine.

I took it to the Apple Store, who said they'd have to replace something at a cost of £75, which was fine. Just over a week later, they called and said that hadn't worked, and that it was actually the logic board that needed replacing, at a cost of £385, more than the value of the computer. We decided it wasn't worth it.

Yesterday however, I took it to a friends and connected it to his monitor, and even though the screen was dark on the MacBook, it came up fine on the monitor.

To me, it seems strange that it's a logic board issue when it works fine with an external display. Anyone have any thoughts?

 

[eman]

I would replace the inverter first and the battery connector second.

 

[timsutcliffe]

I think it was the inverter board and cable that they tried replacing initially, but that didn't solve the problem.

I don't understand why it works fine with an external screen if it's a logic board problem.

 

[balang47]

i have the same problem, the backlight turns off after about 20 seconds. I can use the computer as the backlight stays on if i have it at the lowest setting. Does no one know how to fix this?

 

[l.a.rossmann]

What model macbook is it?

 

[l.a.rossmann]

I think it was the inverter board and cable that they tried replacing initially, but that didn't solve the problem.

I don't understand why it works fine with an external screen if it's a logic board problem.

The logic board sends volage to the inverter which tells it to turn the backlight on in the screen. The backlight is separate from the data connector which sends the actual image information to the screen.

When you use an external monitor, it is sending the image information to the external monitor which has its own means for powering its backlight. When using an external monitor, the macbook is not responsible for powering the backlight in that display.

 

[timsutcliffe]

Thanks for the help in understanding why this might be, however, things have changed for the better.

I was using the MacBook via screen sharing yesterday, and there were some updates available. Safari 5, and OS X 10.6.3 as well. I ran the updates, and then thought i'd use the computer to do what I was doing, while the backlight remained on.

This time though, the backlight didn't go out, and has been functioning as normal since last night, and this morning. This is after two months of not being used. The other thing which makes it slightly interesting, is that earlier that evening i'd ordered a new MacBook to replace it.

So hopefully the computer is now working again, and i'll be able to sell it on.

 

[darthpaul]

same problem...

I have the same issue as balang, if I have the brightness on the very lowest setting the backlight works, but if i try to increase it it just goes dark...I'm going to the apple store tomorrow morning to see if they can fix it. I got my macbook in june of 2006, so it's fairly old. I have had my logic board replaced twice, but that was back in 2007 - when I still had applecare. I forgot to renew applecare last year when it expired...so I think I'm s.o.l.