iMac black screen booting with external display

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Level 1

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iMac black screen booting with external display

Good day to all.

I have iMac 21" 2015 retina with last OS. I have connected external display (Philips HD TV) with HDMI cable.

Second display (TV) is working well until i turn off iMac (i am not using mirror).

When I turn off and try to start again (no matter if TV is on/off) i am getting light black screen on iMac without option to login.

In this situation I have to turn off iMac by force and to switch off HDMI with thunderbolt cable from Mac and to boot again.

When i unable automatic login (without using password) all is working/booting fine but since i am working in office environment it will be good to use password for login.

Can you please help with this subject?

Thanks to all in advance.

iMac, OS X Yosemite (10.10.1)

Posted on Feb 9, 2016 3:53 AM

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Answer 1

CarlAVII

Community Specialist

Feb 10, 2016 9:14 AM in response to ivanhorus

Howdy ivanhorus,

I understand that you're having some trouble with your Mac's internal display when you've connected your iMac to an external display. While the article linked below may not seem particularly relevant on account of the title, the steps outlined should help stabilize your iMac, as the issue appears to only occur when an external display is connected.

Get help with video issues on external displays connected to your Mac
https://support.apple.com/en-us/HT201177

Sincerely

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Answer 2

rkaufmann87

Level 10

140,478 points

Feb 10, 2016 9:18 AM in response to ivanhorus

When you say the "last OS" please be specific, if you are not sure please click the Apple symbol in the upper left of the display and select About this Mac.

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