User profile for user: ubetterdont
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Connecting a 2009 iMac to a 2019 Macbook Pro to use as a monitor

I'm trying to connect a 2009 iMac to a 2019 Macbook Pro to use as a monitor. I can't get it to recognize. I bought the Thunderbolt 3 (USB C) to Thunderbolt 2 adapter. I'm using Thunderbolt 2 cable. When I go to display preferences the option to extend monitors doesn't show up. If I hold down the option key I can see the Detect Displays button (not visible without holding down the option key) but nothing happens when I click it. I've also tried using a mini display port cable but, again, I don't see an option to extend monitors in system preferences


Anybody have a solution?

Posted on Dec 17, 2019 4:21 PM

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User profile for user: Malcolm J. Rayfield
Malcolm J. Rayfield
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Posted on Dec 18, 2019 2:11 AM

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

"27-inch iMac models introduced in 2009 and 2010: Use a Mini DisplayPort cable"


About the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter - Apple Support

"This adapter is not compatible with displays that use DisplayPort or Mini DisplayPort"

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User profile for user: Malcolm J. Rayfield
Malcolm J. Rayfield
User level: Level 7
23,077 points

Dec 18, 2019 2:11 AM in response to ubetterdont

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

"27-inch iMac models introduced in 2009 and 2010: Use a Mini DisplayPort cable"


About the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter - Apple Support

"This adapter is not compatible with displays that use DisplayPort or Mini DisplayPort"

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User profile for user: Malcolm J. Rayfield
Malcolm J. Rayfield
User level: Level 7
23,077 points

Dec 17, 2019 8:19 PM in response to ubetterdont

You can't use Thunderbolt adapters or Thunderbolt cables with the 2009 iMac. You need USB-C to Mini DisplayPort adapters or cables, such as:

https://www.startech.com/AV/display-and-video-adapters/usb-c-video-adapters/usb-c-mini-displayport-cable~CDP2MDPMM6B

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User profile for user: Malcolm J. Rayfield
Malcolm J. Rayfield
User level: Level 7
23,077 points

Dec 18, 2019 2:30 AM in response to ubetterdont

Another option is to use a Mini DisplayPort cable with a USB-C to Mini DisplayPort adapter:

https://www.uptab.com/usb-c-type-c-to-mini-displayport-adapter-4k-60hz-silver/

This adapter has an extra USB-C port that can be used for the Mac's charger, leaving more free USB-C ports on the computer.

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User profile for user: ubetterdont
ubetterdont Author
User level: Level 1
8 points

Dec 20, 2019 4:13 PM in response to Malcolm J. Rayfield

Thank you very much for your help! Apple doesn't even make this kind of cable but they recommended Belkin and I bought a USB-C to Mini DP cable and the set up works good now. I can't control the brightness (only adjusts on the macbook) but I mostly use dark mode so it's all good.

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Connecting a 2009 iMac to a 2019 Macbook Pro to use as a monitor

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