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User profile for user: 1norcoast
1norcoast Author
User level: Level 1
9 points

External monitor blues

Having read the Apple description of setting up an 8-year-old external monitor with my new iMac 27", I am failing to determine why the second display will not connect.


My old iMac connected to the monitor by way of a mini DisplayPort cable to the monitor's DVI cable. When I bought the new computer I was told to buy a USB-C adapter to connect to the other adapter (Miniport) That has not worked, the second monitor is not seen by my computer.


Today purchased a HDMI cable and appropriate USB-C adapter, using the HDMI con section on the monitor. The monitor messages "check the cable connection".


Any insights for me? Do I need to replace the monitor?

Jim / Sitka, AK

iMac 27″, macOS 10.13

Posted on Mar 29, 2021 5:53 PM

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User profile for user: rkaufmann87
rkaufmann87
User level: Level 10
145,294 points

Posted on Mar 29, 2021 8:08 PM

Basically you are wasting your time, Target Display Mode will not work with a 2020 iMac. Do yourself a favor, return the expensive cables you bought, visit your local Costco and buy yourself an nice 1080P display for about $100-$130.

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User profile for user: jpdemers
jpdemers
User level: Level 1
105 points

Apr 3, 2021 10:58 AM in response to 1norcoast

Ignore the above advice. Target Display Mode is not relevant to an external monitor, unless that monitor is an iMac.

I had a problem connecting a Dell monitor to my MacBook Pro; the problem turned out to be a cheap $10 HDMI adapter, when I needed an "active" adapter that performed the necessary digital voodoo on the signal. The one that worked for me cost $20 on Amazon.

You can get a $7 adapter that has HDMI at one end and USB-3 at the other, but it's not going to work. (I have no idea what they're actually good for.) Look for an "active" adapter in the $20-$30 price range. Apple's USB-C Digital AV Multiport Adapter costs a ridiculous $67, but you know it will work, and it should drive any monitor that you might imagine getting in the future.


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External monitor blues

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