Mid 2009 Model A1278 / 2.26 or 2.53 GHz Core 2 Duo processor EMC 2326

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SMC/Battery or Logic Board problem? Strange behavior.

Hello, everyone!

I am with a strange problem in my dad's macbook pro mid 2009.

When I boot it with the battery plugged in, it simply doesn't light out the screen backlight. For a moment I thought this could be the WLED chip that blew, but then I unscrew the bottom tamp, removed the battery, unplugged and plugged again the magsafe... voila! It stars again with everything working except the backlight keyboard (funny because in the startup, it blinks).

But then I turn off, plug the battery in and sometimes it starts normally, sometimes not. but certainly on the next day, it gives me the exact same problem and I have to do everything again. Worth saying that if I perform a SMC reset nothing happens.

I am doing it everyday for the past three weeks. I thought it could be a faulty RAM, I changed it and nothing. If I start with the battery plugged in, I can only use the computer with an external monitor "normally".

I think it could be some problem with the SMC, but apparently there's no other version for me to flash.

Can someone please give me any sign of light?

Answered! View the answer I have this problem too

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and I found out... If i restart the computer (without the battery plugged), it goes the same way. I have to unplug and plug the magsafe to get it back.

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Can you tell us what light/s you are speaking about? Is it the MagSafe cord LED (Green/Orange). The battery checker LED's (8 little Green LED's) along the left front side of the case when you press the battery checker. Or, the Sleep light (White LED on front). The keyboard backlight LED's (White).

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the screen backlight.

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Thanks for your clarifications Thats what I had thought. Some of your now edited question didn't quite make sense the first time.

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I have absolutely no idea what could can cause this. Even with the battery off, If I restart the computer it gives me the same problem.

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You may want to check your screens backlight settings. Your ambient sensor maybe having problems when set to Auto.

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Did you look at your screens backlight settings? Try setting it to manual and set the backlight about 1/2 ~ 2/3 bright. Does it stay on now.

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No... nothing at all. Tried that and it didn't worked. Is there any way to manually take the ambient light sensor off? Thus, the keyboard backlight does not work when the screen works. That's strange as well.

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abtremarin will be eternally grateful.
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