I replaced the LCD, but the backlight turns off after 2 seconds?

Question

MacBook Core Duo

Mitte 2006 / Modellnummer A1181 / schwarzes oder weißes Gehäuse / 1,83 oder 2,0 GHz Intel Core Duo Prozessor.

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Roy @roy90773

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Veröffentlicht: 25. Jun 2010

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I replaced the LCD, but the backlight turns off after 2 seconds?

Did I mess up the connection to the inverter? The screen looks great for about 2 seconds at start up, after waking from sleep (also for 2 seconds), and when I take the brightness from all the way down to anything up. But it never stays on for more than a couple seconds. I can still see images on the screen it's just not illuminated.

A magnet did drop out while I was re-installing the LCD and I can't tell where it is supposed to go. Does it trigger a control to keep the backlight on? It is not one of the 4 magnets in the top corners of the LCD case. Thanks for any help you can give!

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+ well stated question

25. Jun 2010 von mayer

A quick follow up. The replacement LCD must have been a refurb. The wires coming out of it to plug into the inverter had been repaired. I sent the screen back and ordered another from a different vendor. This one worked perfectly. It must have been the connection to the inverter! Thanks for all the help and advice

28. Jul 2010 von Roy

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markus weiher @markusweiher

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there are most likely 3 possible problems

the inverter cable is scuffed or clamped
the backlight tubes (CCFL) are defective
the inverter is faulty

i marked the magnet position on the picture, but it has nothing to do with the backlight problem. did you change the inverter too ?

check the position of the inverter cable

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Good Pics +

25. Jun 2010 von Majesty

+ nice answer

25. Jun 2010 von mayer

I got the magnet back in place, but, like you said no effect on the backlight. I did not change the inverter, and I didn't take the case apart to get into the area you showed. I only removed the LCD frame from the enclosure. Could be a cable, I may try to put the old one back in to see if it acts the same way. The old one was working fine apart from the cracks.

It's strange that I can get it to come on repeatedly by changing the brightness from 0 to 1, but it goes off after 2 seconds! It seems as though everything can function, but something is sending a signal to turn the backlight off.

25. Jun 2010 von Roy

Took it by the Apple store to talk to a "Genius" He agreed it was somehow related to the inverter. Thanks for your help!

25. Jun 2010 von Roy

since you didn't change those parts - it's possible that the ccfl tubes inside the lcd are bad. good idea to change the lcd back, if the backlight works normal, the ccfl tubes are bad - they can be replaced - but you have to be careful - they are very fragile

25. Jun 2010 von markus weiher

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A quick follow up. The replacement LCD must have been a refurb. The wires coming out of it to plug into the inverter had been repaired. I sent the screen back and ordered another from a different vendor. This one worked perfectly. It must have been the connection to the inverter! Thanks for all the help and advice — Roy
I got the magnet back in place, but, like you said no effect on the backlight. I did not change the inverter, and I didn't take the case apart to get into the area you showed. I only removed the LCD frame from the enclosure. Could be a cable, I may try to put the old one back in to see if it acts the same way. The old one was working fine apart from the cracks.

It's strange that I can get it to come on repeatedly by changing the brightness from 0 to 1, but it goes off after 2 seconds! It seems as though everything can function, but something is sending a signal to turn the backlight off. — Roy
Took it by the Apple store to talk to a "Genius" He agreed it was somehow related to the inverter. Thanks for your help! — Roy
since you didn't change those parts - it's possible that the ccfl tubes inside the lcd are bad. good idea to change the lcd back, if the backlight works normal, the ccfl tubes are bad - they can be replaced - but you have to be careful - they are very fragile — markus weiher

lemerise @lemerise Rep: 37,6 Tsd. 315 66 72 · Answer 1 · 2010-06-25T16:16:53-07:00

lemerise @lemerise

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If the display lights for 2 seconds then the backlight lamp should be working. I would suspect a bad inverter board or a bad logic board. Any liquid spilled on the MB ?

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dadioh @dadioh Rep: 221 7 4 · Answer 2 · 2010-07-28T10:11:00-07:00

dadioh @dadioh

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When it dims do you see the screen display the dimming logo (the one that hows the brightness sun logo and the bars decreasing below it? The reason I ask is if the key on the keyboard that controls brightness is "stuck" then it would continuously dim the display. You could verify by disconnecting the built in keyboard and using an external keyboard.

Just a thought...

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These keys shouldn't be active just after startup.

28. Jul 2010 von remacberlin

Yes I did see the icon, turns out it was a problem with the wires and/or connector to the inverter. thanks

28. Jul 2010 von Roy

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