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13" aluminum unibody, 2.0 or 2.4 GHz Core 2 Duo processor.

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logic board not sending any video signal to display.

i got a broken macbook unibody model a1278 that im trying to fix. when the machine is turned on it does full startup with chimes, but there is no display. to make sure it is not the lcd/display i tested it on another macbook unibody and is fully functional. so i assume there is something wrong with signal getting to display.

how should i go about repairing the logic board so i can get my screen working again???

any help in this situation would be wonderful

thanks

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Check with an external monitor. If you get that working, you know that your video board is working.

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You say <<when the machine is turned on it does full startup with chimes, but there is no display>> do you mean the screen is completely black or you have a lightened gray screen ?

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so i hooked it up to my tv through the mini display port and works wonderfully. when hooked up to the macbook screen its black. when i put flashlight to screen there is nothing there.

i bought a new lvds display connecter for screen. to make sure it wasn't screen i hooked that up to another macbook i have. when hooked up to that the screen worked wonderfully. so now im truely stumped. or could it be the actual lvd socket on logic board ????

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Hi, Hrd...

Try open top casing of system unit and check connector of screen and logic board, maybe it's disconnected. Second: Have you saw any picture in dim on screen? If exist that mean 'back lamp' is faulty. Just replace it at stall has expertise and part to install it.

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unfortunalty, i tried screen on another macbook and it worked great... so now im stumped . is it possible that the lvds socket is to blame ????

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IIRC there is a sensor that detects the lid is closed on your model. A Hall Effect Sensor and magnet? Have you pinched the cable? If so perhaps the system "thinks' the lid is closed so shuts off the display

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If the new lvd cable works fine and the display works great then it sound like the ribbon isn't connecting to the logic board. Clean the connector on the logic board and then ribbon. Use a mixture of 60% alcohol and 40% water. Use a q-tip to clean the connectors but before that use a toothbrush or something similar that won't damage the logic board and brush the connector on the logic board side. Then clean it with Q-tip(make sure the Q-tip isn't soak en water). Let it dry for about 30 minutes. Make sure that you push the ribbon all the way in and then push the lock down. Also check on the logic board connector the pin to make sure they're straight and not touching. I recommend to reset PRAM and SMC too.

Here's a link for that:

http://allnewmac.wordpress.com/2009/06/2...

Hope that helps. Good luck with that.

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