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Released June 2012 / Core i7 processor with Turbo Boost / Up to 1 GB GDDR5 Video RAM

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Screen turns black after Grey apple bootscreen

Hey community,

Got a big problem with my 15 inch mid 2012 MacBook Pro.

I replaced the screen with a 1680x1050 matte unit which was faulty. The image was heavily distorted with lines so I needed to put back in my old 1400x900 panel.

Problem is:

  • Boot appears fine (Grey apple with loading bar)
  • As soon as login happens it turns black. Brightness control still works though.
  • When I attach an external monitor mirrored every now and then the display will show the screen correctly depending on which application I am using in the foreground.
  • When I start internet recovery, selecting the network it will turn black but screen reappears for password.
  • When recovery starts I can see the mouse / Beachvolleyball with black background until language selection turns up. This is visible for like a few milliseconds. Then black again.
  • When display turns off by itself and is woken up again I can see the language selection again for a few milliseconds.

Same when for example switching resolution or plugging in the external monitor.

Working with external monitor is fine though so I am pretty sure the GPU isn't fried.

Tried a replacement LVDS cable as well as a brand new 1680x1050 panel. LVDS cable does not change anything, new panel will stay black (with backlight) all the time.

I have reset NVRAM & SMC many times but no luck.

Any ideas are very welcome

Edit : just run the AHT... Error code is 4sns : VPOR - 0.000

If I understand correctly I got a power issue (on the gpu / monitor I guess)

So I guess the used/defective panel did fry something on my logicboard?

I made two videos. First was the used defective panel I bought, second is the old panel and the problem I have :

https://youtu.be/RzW4bFr1NQ8

https://youtu.be/qykSuuANnNQ

EDIT: Closing / opening the lid shortly gives me screen (like half a second maybe)

Update (11/26/2017)

Looks like the defective panel fried the igp.

ASD fails gmux to IG as well as all internal graphics test.

Answer this question I have this problem too

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4SNS VPOR is a PBUS (power bus) voltage issue on the logic board.

Did you have a liquid spill at some point? I'm suspecting the logic board has some corrosion, or was damaged somehow.

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Hi Dan. No liquid damage on that board. a fried Ethernet transistor though, desoldered that one long time ago. Worked fine without it. just did a full clean with isopropanol. No corrosion as far as i can see. Haven't run a new AHT yet though. Besides replacing the panel nothing was changed. Worked fine before

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I'd agree with you..probably the Hd panel or cable was faulty and shorted something on the logic board, possibly along the backlight driver line. Would check voltages of the driver Ic and surrounding components to start with.

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Arne Ziegert will be eternally grateful.
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