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User profile for user: AnnaDcz
AnnaDcz Author
User level: Level 1
4 points

Thunderbolt not detecting connected MacBook Pro

Hi,


I have a question. I'd like to use my iMac (27", mid 2011) as a second screen for my MacBook Pro 2019 but it's not detecting any connection. It says No devices connected for both Thunderbolt slots.


Can you help me with this, please? I tried to download Thunderbolt firmware update, but it said my iMac don't need it.


I don't want to sell this iMac but would like to use it for now as a external screen.


Many thanks for you advices,

Anna

iMac 27", macOS 10.13

Posted on Jan 7, 2020 4:23 AM

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User profile for user: BDAqua
BDAqua
User level: Level 10
245,651 points

Posted on Jan 7, 2020 11:13 AM

Hi Anna,


Press Command-F2 on the iMac, does the iMac then show up in Displays Pref Pane on the MBP?


If target display mode doesn't work

If your iMac doesn't show the desktop of your other Mac, try these steps first:


Restart your iMac.

Restart the other Mac.

Unplug the Thunderbolt or Mini DisplayPort cable from the other Mac, then plug it back in.

Press Command-F2 on the iMac.

If that doesn't work, try these other solutions:


If you're currently logged in to the iMac that you want to use as a display, choose Apple menu  > Log Out to return to the login window. Then press Command-F2 again.

Choose Apple menu  > System Preferences, then click Keyboard. If ”Use F1, F2, etc. keys as standard function keys” is selected, target display mode uses Command-Fn-F2 instead of Command-F2. It might also help to use the keyboard that came with your iMac. Some third-party keyboards and older Apple keyboards don't support target display mode.

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User profile for user: BDAqua
BDAqua
User level: Level 10
245,651 points

Jan 7, 2020 11:13 AM in response to AnnaDcz

Hi Anna,


Press Command-F2 on the iMac, does the iMac then show up in Displays Pref Pane on the MBP?


If target display mode doesn't work

If your iMac doesn't show the desktop of your other Mac, try these steps first:


Restart your iMac.

Restart the other Mac.

Unplug the Thunderbolt or Mini DisplayPort cable from the other Mac, then plug it back in.

Press Command-F2 on the iMac.

If that doesn't work, try these other solutions:


If you're currently logged in to the iMac that you want to use as a display, choose Apple menu  > Log Out to return to the login window. Then press Command-F2 again.

Choose Apple menu  > System Preferences, then click Keyboard. If ”Use F1, F2, etc. keys as standard function keys” is selected, target display mode uses Command-Fn-F2 instead of Command-F2. It might also help to use the keyboard that came with your iMac. Some third-party keyboards and older Apple keyboards don't support target display mode.

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Thunderbolt not detecting connected MacBook Pro

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