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Mid 2012 model, A1278 / 2.5 GHz i5 or 2.9 GHz i7 processor.

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Black Screen - No Display - External Display OK

I have a Mid 2012 MBP 13" 2.9 Ghz i7 here that is baffling us...

It chimes and that is it - No Display, just stays black.

The GPU was fine as it only went in for a backlight fuse repair.

WE CAN RULE OUT the following as they have been tested on other units:

Screen / LCD cable / SSD / RAM / Keyboard / Touch pad & Battery are all good.

The backlight fuse is new and OK & display voltages are also OK.

External display is OK. Just nothing displays on the units screen.

SMC & PRAM have been reset multiple times in testing.

Upon booting we have a chime and that's it, after some time if you press any key it will flash the screen indicating that the backlight is OK. But nothing else The LCD connector is clean and shows no sign of wear or corrosion and also gives voltage readings. Are there any other voltage lines that we need to check that maybe have been missed upon to check or can anyone point us to what they personally would check from the start for voltages regarding displaying graphics? @oldturkey03 Any suggestions? What line is responsible for the display working from the connector backwards?

Similar to this issue Display Shows Backlight but No Image

Beantwoord deze vraag Dit probleem heb ik ook

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Ja Nee
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FYI - The 13” only has the Intel Iris graphics engine. If you clean off the thermal paste inspect the smaller of the two chips that’s the I/O and graphics services. Often I find the chip is fractured.

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@danj Isn't the Iris Engine only on Retina displays? But OK, will check for any damage under the micheal scope tomorrow. I did replace the paste previously and all was working well until it had a backlight issue, we fixed that, worked for a few days then we are with no display.....

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@livfe - Review EveryMac as different series used different solutions. The 2010 and older 13” used a combo GPU-I/O chip solution both AMD and NVIDIA were used. The early 2011 was the first to use the Iris engine in the 13”.

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@danj OK to clarify this is regarding a 2012 A1278 2.9 i7

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@livfe - Here’s that exact system: 2012 13” 2.9GHz i7 MacBook Pro jump down to Video Card: there you’ll find Intel’s Iris HD Graphics 4000 listed.

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How did you confirm the functionality of the screen / LCD cable / SSD / RAM / keyboard / trackpad / battery / new backlight fuse? Also, have you tried a PRAM or SMC reset? If the backlight fuse had failed previously, it might've been due to a larger issue with the display logic. If you've fully confirmed the health of the other components, then my best guess is that there's a fault on the logic board somewhere, but to figure out where you'll need to investigate the related circuits on the board. Good luck!

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Ja Nee
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Please read the question as it clearly says we tested everything (Except Backlight Fuse) on another unit and all working fine. Yes of course it is a board issue somewhere and that is what I am asking..... the 'answer' does not really provide any answer sorry. Dan suggests to check the Graphic chip for damage, other than thet the names of the rails to check on a board view might help trace anything if it isn't the GPU itslef which I think is unlikely as external is displaying OK.....

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My bad, I totally failed at reading your question! Sorry I don't have a good solution. I agree though that it doesn't sound like a GPU issue since it's working on an external monitor. If you've already confirmed everything going to the display connector (J9000) is working as expected, then I'm at a loss. If you have access to an ASD you could run ASD 155 using an external monitor to see if it gives you any information about what's failing on the board. Good luck!

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livfe zal eeuwig dankbaar zijn.
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