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

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Screen backlight not working

2 days ago I was opening my MBP (13.3" mid 2012) trying to figure out why the right hinge does a strange sound when closing the lid, watched a few tutorials on YouTube and I opened up the laptop, I disconnected the flex cable and accidentally dropped it on the motherboard, something did a short and now the laptop works fine but no backlight on the screen (Did the apple logo test)

I had the exact same issue (and situation with the exact same last 4 serial digits) that this guy had: Backlight not working found fuse open circuit

Any help please? I almost cryed mi eyes out LOL

Answered! View the answer I have this problem too

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3 Answers

Chosen Solution

Finally decided to get an used Logic Board for around $200, now the Mac works pretty fine, this means that the problem was not the LCD but the backlight fuse, I know this was the easiest solution but I don't trust the component-level technicians here in Chile.

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Most Helpful Answer

With help of luck you have blown the backlight fuse.

To be able tell you need a multimeter to test the fuse if its good or bad

To be able to fix you will need a Soldering station and skill.

If the fuse is good then things gets more complicated but if the fuse is bad

needs to be remove and replace with good one then see if it will fix the problem.

google (a1278 backlight fuse )and see how Louis does .

I hope it helps .

Thanks .

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Thanks for the answer, tomorrow I'm buying a multimeter, can you tell me how can I test the fuse? thanks in advance!


Use resistance mode on meter touch leads on both ends OL means its blown , if it gives you a reading like 0.01 you have resistance which means the fuse is intact.


Also If you dont have any experience Its easier to google a1278 backlight fuse and see the videos . There is videos shows exactly where you need to look and how to measure .


So apparently the problem may be the LP8550 chip and/or the "P" fuse, I'm gonna buy a couple of both components, they are not expensive, I'm gonna try to test the components first!


I would lean more towards the display, i've seen this a few times on impact damage the bulb was broken under the lcd. If you do not have fine tip multimeter test leads testing is not advised the pins are very close and you could cause short.


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It's either backlight fuse, drive chip, lcd or lcd cable. Start with LCD first.


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