Target Display Mode on iMac (27-inch, mid-2010) and Macbook Pro (16-inch, 2019)

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Target Display Mode on iMac (27-inch, mid-2010) and Macbook Pro (16-inch, 2019)

I'm trying to use my iMac as a second monitor for my Macbook and I'm running into some trouble with getting targeted display mode to work.

I installed macOS Catalina on my Macbook (it originally ran Big Sur) and my iMac runs macOS Sierra so both should be compatible.

The cable I'm using is a Mini DisplayPort to HDMI, which I'm connecting to my Macbook through a mini docking station (connected via Thunderbolt-3). After some more searching, it seems the sure fire way to use Target Display Mode is with a 1-to-1 cable connection (i.e. Mini DP to Mini DP).

Is there any way around this so that I can connect my Macbook? Would Mini DP to Thunderbolt-3/USB-C work?

iMac 27″, macOS 10.12

Posted on Jun 3, 2021 10:12 PM

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Answer 1

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rkaufmann87

Level 10

144,802 points

Jun 4, 2021 7:24 AM in response to souppeh

Target Display Mode has been dead for over 6 years and is no longer supported. Have you considered simply getting an external display for your MBP? Much easier to use, no expensive cables needed, dead reliable and external displays are inexpensive.

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Answer 2

souppeh Author

Level 1

8 points

Jun 4, 2021 12:15 PM in response to Allan Jones

Thanks for your insight!

I ordered a Thunderbolt-3 to Mini DisplayPort cable from Amazon (StarTech.com 1m / 3.3ft USB-C to Mini DisplayPort Cable - 4K 60Hz - Black - USB 3.1 Type C to mDP Adapter) just to avoid adapters and simplify the connection as much as possible since using a dock may have already been problematic as you said.

More than one review on Amazon said TDM worked perfectly for them using it with very similar set-ups, so I have some hope. This is probably my last ditch effort to avoid a ton of trial and error with different connections.

Thanks again for your advice!

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Answer 3

souppeh Author

Level 1

8 points

Jun 4, 2021 7:50 AM in response to rkaufmann87

Mid-2010 iMacs have Target Display Mode (https://support.apple.com/en-us/HT204592). Everything I've found thus far indicates that it is possible, I just want to know if my particular set-up will work with MiniDP to Thunderbolt-3/USB-C.

I'm not interested in using a different monitor because this would be my preferred set-up. I want to be able to continue to use my iMac as my personal computer and switch to also use it as the monitor for my Macbook (which is my work computer). I just want that flexibility and to not have to rearrange my workstation when I want to switch between computers.

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Answer 4

souppeh Author

Level 1

8 points

Jun 9, 2021 7:16 AM in response to souppeh

Quick update to close this thread, the cable I ordered worked perfectly!

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Answer 5

Allan Jones

Level 9

72,674 points

Jun 4, 2021 8:36 AM in response to souppeh

WOW! Apple "unarchived" the once-dead TDM article and polished some of the awkward sections. That almost never happens. Unfortunately there are still some obfuscation and errors.

Troubleshooting TDM remotely is very hard because it too often takes trial and error with expensive cables and adaptors. I believe you have hit the nail on the head with this:

The cable I'm using is a Mini DisplayPort to HDMI, which I'm connecting to my Macbook through a mini docking station (connected via Thunderbolt-3). After some more searching, it seems the sure fire way to use Target Display Mode is with a 1-to-1 cable connection (i.e. Mini DP to Mini DP).

Your devices and OS version support TDM, so it must be a cabling issues. Any hub/dock is problematic. Historically, and only documented in posts here, others had results with similar models using this chain:

<MBP 2019>-----Thunderbolt 3 cable------[Thunderbolt 3 to Thunderbolt 2 Adapter] <2010 iMac 27>

Again its trial and error. TDM has never been a slam-dunk. In spite of the article revision, there are still mysteries involved and you may end up spending more money of cables and adapters. The above cable adapter combo can cost US$60-90.

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