Use iMac as a monitor for MacBook

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Level 1

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Use iMac as a monitor for MacBook

I have a 21.5-inch, Late 2012 iMac running macOS Mojave and a 2016 Macbook Pro running Catalina. I am trying to use the iMac as an external monitor for my Macbook and I've found that I need a Thunderbolt 3 to Thunderbolt 2 adapter as well as a Thunderbolt cable.

How does the Thunderbolt 3/Thunderbolt 2 adapter differ from a USB-C/Mini DisplayPort adapter?

Also, I've found that Target Display mode does not work on macOS Mojave. Does this mean that I will not be able to use the iMac as an external monitor for my Macbook regardless of the adapters and cables I have?

[Re-Titled by Moderator]

Posted on Jun 25, 2020 8:00 PM

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Answer 1

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VikingOSX

Community+ 2024

Level 10

116,753 points

Jun 26, 2020 10:31 AM in response to Jasonj9630

On your MacBook Pro, visit System Preferences : Sharing : and check Screen Sharing. On your iMac, drag and drop the Screen Sharing application from /System/Library/CoreServices/Applications to your Dock. Then click the Screen Sharing app, and enter the hostname.local of your MacBook Pro (after sufficient time for it to boot). You will have full keyboard, mouse, and drag/drop capability from your MBP in this Screen Sharing window. It will not be a full screen effect as it would be using Target Display Mode.

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Answer 2

BobHarris

Level 9

55,073 points

Jun 26, 2020 4:39 PM in response to VikingOSX

https://support.apple.com/en-us/HT204592

27-inch iMac models introduced in 2009 and 2010: Use a Mini DisplayPort cable to connect your iMac to a Mini DisplayPort or Thunderbolt or Thunderbolt 2 port on the other Mac.
All iMac models introduced in 2011, 2012, 2013, and mid 2014: Use a Thunderbolt cable to connect your iMac to a Thunderbolt or Thunderbolt 2 port on the other Mac. If the other Mac uses Thunderbolt 3, you can use the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter with your cable.

Jasonj9630

is using a Late 2012, which should fit in the "All iMac models" catagory.

But I still think he can use a USB-C to mini-DisplayPort adapter. Then again, I could be totally wrong.

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Answer 3

Jun 26, 2020 6:10 AM in response to Jasonj9630

Two blows against you. Target Display Mode was only for 27 inch iMacs from 2009 to 2013, and the iMac must be running High Sierra or earlier.

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Answer 4

BobHarris

Level 9

55,073 points

Jun 26, 2020 3:59 PM in response to Jasonj9630

https://www.lifewire.com/use-imac-as-monitor-with-target-display-mode-2260906

You do not need a thunderbolt 2 cable. You just need a DisplayPort cable with a mini-DisplayPort plug on the iMac end.

The iMac's Thunderbolt 2 port is Also a DisplayPort, and it is DisplayPort that you need in Target Display Mode.

You could use a USB-C to mini-DisplayPort cable. ( I successfully used a cable like this between my Late 2016 15" Macbook Pro, and a Late 2009 27" iMac, so I know it can be done).

Again, DO NOT search for Thunderbolt. Search for DisplayPort and you will find what you need.

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