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Model A1297 Unibody: Early 2009, Mid 2009, Mid 2010, Early 2011 & Late 2011

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Mac display screen works only when external monitor is connected

Hello all,

I have been trying everything over the last 3 weeks trying to fix this computer, and I am now to the last option which is contact you all for an answer.

I have this 2011 Macbook pro 17" on OS X EL captain which gives me a flashing dark Bleu screen on normal mode. the start up is successful, but it just now showing anything on the screen beside flashing every 3 seconds.

1) I connect an external monitor to the DisplayPort the computer On and works just great, with that said, i have both the mac monitor and the external monitor(my TV) work fine. I unplug the external monitor to see if the mac monitor will stay fine NOP it did not. The mac screen went dark bleu and start flashing again.

2) I tried safe mode and the mac monitor works fine with out the external monitor attached to the displayPort.

If i want to use the computer in normal MODE an external monitor as to attached to the displayPort. Even if i turn the external monitor of the computer monitor still work fine, but the moment I unplug the external monitor the dark blue screen comes on, and the computer start to flash and i can't see anything at all.

THANK YOU IN ADVANCE.

Answered! View the answer I have this problem too

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I tried another drive, reinstalled the OS X, tried recovery mode, etc. I still get the same problem.

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Hi Zanz Zan ! Did you find any solution eventually? Because I have the same problem ... almost

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Did you read the post? There is a chosen solution, which means it worked

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Yes . And i have the same problem

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4 Answers

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If your display works fine in Safe Mode which is what you seem to have said, it's a software issue.

You may have picked up a virus. I would boot it in Target Mode with another Mac that has a good (paid of) anti-virus such as Symantec.

You can also try starting in recovery mode and running disk Utilities. Here's how:

http://www.idownloadblog.com/2016/02/25/...

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Sounds like the display issue may be caused by the graphics processor, all 15 & 17" 2011 macbook pros have been recalled for that reason. It's possible you can have it fixed free of charge if it's a 2011 model. See here https://www.apple.com/au/support/macbook...

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I have the same problem but on a 2014 MB Pro 15". The Apple Macbook repair program doesnt cover this model, though the symptoms are exactly the same as those on the covered models. Any other suggestions other than replacing the logic board?

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Service people who work on replacing the GPU on MBP 17 motherboards says that if

the graphics look OK on an external monitor then it's not the GPU.

So they are reluctant to accept taking on to replace the GPU on my machine.

If I disconnect the external monitor and use the gfxCardStatus app to switch

to "Integrated" (Intel graphics) then the LCD display perfectly.

But the only way to connect an external monitor (and I need that) is that the "Discrete" graphics (NVidia) is active. And then as mentioned the LCD does not show colors correctly although the external monitor works.

What should I troubleshoot ? Is this a known issue with solutions ?

The only case I see out there where people are having trouble is where the *external* monitor is acting up.

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ZANZ ZAN will be eternally grateful.
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