Using a 2013 iMac as target display

Question

Using a 2013 iMac as target display

I have a 2013 27" iMac (OSX Catalina) that I want to use as a target display. I am using the apple thunderbolt2 cable with a thunderbolt3 adapter. I am using an iMac 2020 (OSX Catalina) as the source. When I press Cmd+F2 nothing happens.

I have tried resetting the SMC (shutting down both computers and unplugging for 15s)

All keyboards are original apple keyboards and the 2013 keyboard is the one that came with the computer. I see the Cmd+F2 are being pressed (visualising the keyboard viewer).

I have tried different apple IDs or same awoke IDs on both computers

I successfully but only briefly connected my Macbook Pro 2020 to the 2013 iMac once and has not been able to reproduce that after.

Any help fully appreciated here

iMac, OS X 10.10

Posted on Sep 30, 2020 2:07 AM

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Answer 1

Top-ranking reply

woodmeister50

Level 7

20,473 points

Sep 30, 2020 12:07 PM in response to Malcolm J. Rayfield

Malcolm J. Rayfield wrote:

Catalina on the 2013 iMac is a problem

...

OP is using a 2020 iMac which will not work as per

the updated target display doc:

"You can connect any of these older iMac models to another Mac from 2019 or earlier for use as an external display. Learn how to identify your iMac model."

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Answer 2

BDAqua

Level 10

245,177 points

Sep 30, 2020 2:52 AM in response to Nicolas Weng kan

Supposedly Apple disabled that on the 2020 Macs!?

But if you had it work briefly they must be wrong... wrack your brain as to what steps you took.

You can connect any of these older iMac models to another Mac from 2019 or earlier for use as an external display. Learn how to identify your iMac model.

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Answer 3

Sep 30, 2020 7:15 AM in response to Nicolas Weng kan

Catalina on the 2013 iMac is a problem

Use your iMac as a display with target display mode - Apple Support

"Target display mode requires macOS High Sierra or earlier on the iMac used as the external display. It does not work with macOS Mojave or later."

Maybe your MacBook Pro is a 2019 model, even if purchased in 2020. That might explain it working once. If that's the case, downgrading Mac OS on the 2013 iMac may make it usable as a display for your MacBook Pro. Won't help for the 2020 iMac, though.

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Answer 4

Jeff Donald

Level 7

23,785 points

Sep 30, 2020 3:12 AM in response to Nicolas Weng kan

Confusing issue for many users for sure. In my experience, I’ve never gotten Target Display Mode (TDM) to work on an iMac using any OS higher than 10.13.xx. Is it possible TDM worked the one time and then you updated the OS to what is higher than TDM supports?

Adding to the confusion is that Apple seems to have depreciated support for TDM on sources using any hardware (iMac) newer than the 2019 iMacs. However, there are a few isolated cases of people getting TDM to work with a 2020 iMac as the source, with older 2009 and 2010 iMacs that used the Mini Display Port.

Very confusing indeed. I hope this helps in some way.

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Answer 5

Sep 30, 2020 4:45 AM in response to Nicolas Weng kan

2020 Macs cannot work with any older iMacs configured in

Target Display Mode from 2011 or newer. The feature to work

via Thunderbolt has been completely removed. If you had

a late 2009 or 2010 iMac, it could work as these are MiniDisplayPort

models and that is what they look like when put in Target Display Mode.

Sorry, but there is no hack or magic wand to make it work.

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Using a 2013 iMac as target display

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