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User profile for user: MSJL88
MSJL88 Author
User level: Level 1
4 points

Connecting old iMac to new 24" iMac as Secondary Monitor

I have a new 24" Mac, and I want to connect my old, 2010-vintage iMac as a second monitor. I have the Thunderbolt cable and adapter. I no longer have the original wireless keyboard from the old iMac but can connect the new Magic keyboard with a Lightning cable and it works well. I checked all the equipment and it works on another Mac.


But Command-F2 and nothing happens. Same equipment, same set up, same process but a different result.


Is there something about these new 24" iMacs that do not allow them to connect to older vintage equipment as a monitor? Is there an additional step needed for the new Macs?

iMac Line (2012 and Later)

Posted on Sep 18, 2021 11:41 AM

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User profile for user: rkaufmann87
rkaufmann87
User level: Level 10
143,952 points

Posted on Sep 20, 2021 9:01 PM

It's not going to happen, your new 24" iMac simply does not support TDM. Please read Use your iMac as a display with target display mode - Apple Support. If your 24" needs an external display your only alternative is to buy one, which is less expensive (no expensive cabling) easier to setup and maintain and far more reliable. Oh and there are no work arounds, hacks or anything. If you need an external display, you will need to buy one, they start at about $100.


Also, the 24" M1 iMacs support 1 external display in case you were wondering.

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User profile for user: rkaufmann87
rkaufmann87
User level: Level 10
143,952 points

Sep 20, 2021 9:01 PM in response to MSJL88

It's not going to happen, your new 24" iMac simply does not support TDM. Please read Use your iMac as a display with target display mode - Apple Support. If your 24" needs an external display your only alternative is to buy one, which is less expensive (no expensive cabling) easier to setup and maintain and far more reliable. Oh and there are no work arounds, hacks or anything. If you need an external display, you will need to buy one, they start at about $100.


Also, the 24" M1 iMacs support 1 external display in case you were wondering.

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User profile for user: MSJL88
MSJL88 Author
User level: Level 1
4 points

Sep 20, 2021 8:15 PM in response to KiltedTim

Thanks for the quick response.


That's disappointing, but I suspected that might be the issue.


So this reflects changes is the operating system or is it a hardware issue? I'm trying to see if there is a workaround, and is this just limited to older Macs or can I only use a newer-model monitor as a second monitor with the new Mac?

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Connecting old iMac to new 24" iMac as Secondary Monitor

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