Released June 2012, Model A1278. Intel processor with Turbo Boost, Up to 512 MB DDR5 Video RAM

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Weird display behavior after reassembly and thermal paste application


So I took apart everything and re-applied the thermal paste. Something's definitely wrong after the logic board reassembly; any help to figure it out will be appreciated!

History : I changed the SATA cables twice and figured they were getting destroyed due to overheating, so I'm currently running my SDD on an external USB casing.

This also means, that right now I have a loose, faulty SATA cable (and hence IR sensor/sleep sensor (?) ) inside the machine.

Symptoms :

First, the display didn't work at all. I followed the steps at

No video on lcd, but has video on external monitor

and figured it has something to do with the sleep sensor. When I took out the battery, SATA cable, and BIL and then reattached the battery, the display worked. Then, I tried attaching them back, and the display still works! Here, the laptop was in a vertical position, i.e. standing on one of its sides.

A minute later, I put on the screws, happy, and in the normal horizontal position, it stopped working again.

Right now, I booted it in a vertical position, and turned it around, and it's working, but something is definitely wrong, and I don't know if it will boot again normally in an hour.

Extra notes:

I checked the backlight fuse with a multimeter for continuity and it is OK.

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What happens when you plug in an external display? Also are you seeing the front Sleep indicator waxing and waning or is it in a steady state of being on?


Everything works ok on an external display.

The sleep indicator is not working at all. (as I said, faulty SATA + IR cable.)


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1 Answer

Chosen Solution

As you have bypassed the internet display via an external and the internal hard drive via the USB connected drive, you have two distinct problems and both are related to the cable connectors I suspect you had problems with them.

I would focus on the display cable connection first: Can you take doe good detailed pictures of the board connector and the cable end so we can see the pins.

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