The display on my mom’s 2017 iMac died, and the Apple Store is in the process of replacing it. I last backed her up probably a couple weeks ago before I installed the latest update to Monterey. Hopefully she won’t lose any data in the process. It would have been nice to be able to perform another backup before taking it in, which would have required an external display.
My own iMac is from the same generation and not too much newer. I have no experience with second displays and the connections available on my iMac.
What’s the cheapest setup I could have? I don’t need a big screen (smaller is probably better anyway), and I don’t need a high-quality picture. I just need to be able to see a picture on the screen in an emergency. This is not for a dual-monitor setup that would remain in day-to-day usage.
Any iMac’s Thunderbolt port should be able to provide DisplayPort video to an external monitor with just a compatible cable.
The correct cable will depend on the model iMac you have.
iMacs old enough to have Thunderbolt 1 or 2 (2015 and older models) use a mini DisplayPort cable. So get a generic miniDP-to-DisplayPort cable. Newer iMacs that have Thunderbolt 3 (2017 and later) should use a generic USB-C-to-DisplayPort cable.
So get an inexpensive monitor with DisplayPort input and the corresponding cable. Just plug it in and macOS should do the right thing - displaying either a mirror of the internal display or an extended desktop. Set it up the way you like (I’d suggest mirroring for your purpose) and it will remember the setting for when you need it in the future.
Or use an old TV with an HDMI cable & adapter from the Mac.
But either way the Mac might not switch to the external display without changing the display settings using the (defunct) internal display - there might be a keyboard shortcut to do this.
Try Command Fn F1 (toggles mirroring on my Macbook Air)
If the two machines are on the same LAN…then using Screens and logging into mom’s remotely should work for backing up again, copying files or whatever. Once you’re controlling it remotely then you can turn on sharing if needed and mount the volume elsewhere or copy files locally to a second drive. If you’re planning on using Migration Assistant…I think machines that old have to be put into Target Mode to use MA directly or maybe the machine just needs to be on the same network as the new machine you’re migrating her to as all of the Migration Assistant stuff happens on the new machine, not the one being migrated from.
Everymac.com says that the 2017 iMac has Thunderbolt 3/USB c ports so you would need a Thunderbolt capable monitor as the external…I’ve never tried setting up a second display on an iMac and it might not be possible without being able to see the main display via either remote login or directly in order to configure System Preferences.
The easiest way is probably Screens…and when asked for credentials you need to enter the admin userid and password for her machine…once that is done you should get a window that allows you to control the remote computer. Screens is pretty cheap…and you can even use the iPad version as long as it’s on the same network as her machine although for something like this I would use the desktop since mousing around and clicking is harder if the controlling machine is an iPad.
I’m not so sure about that. A generic monitor with DisplayPort or USB-C input should work. The port should just fall-back to its DisplayPort alternate mode.
You should only need a Thunderbolt monitor if you want to daisy-chain Thunderbolt peripherals off of its downstream ports.
If you only require video, then you should be able to use a USB-C monitor with a C-to-C capable of carrying video (one example) or a DisplayPort monitor with a USB C-to-DisplayPort cable (one example).
FWIIW I connected my Macbook Air to my 32" LG 4K monitor using HDMI instead of USB-c. As expected the resolution was not nearly as good but seemed only marginally worse than the MBA display.
Of course the quality depends on the monitor/TV resolution but as a stand-by display a TV should be fine.
If you’re mirroring the internal display, then that makes sense. The internal display (which is less than 4K resolution) will be scaled to 4K, which will result in a somewhat fuzzy image.
If you’re not mirroring but are instead extending the desktop, then your Mac should be able to output a native 4K image, whether over HDMI or USB/DisplayPort. Depending on the version of HDMI supported by your Mac and your monitor - 4K at 30 Hz requires HDMI 1.3 or later. 4K at 60 Hz without display-stream compression (which produces a somewhat fuzzy image) requires HDMI 2.0 or later.
On the other hand, DisplayPort (what you get from a USB-C connection to a USB monitor) can produce 4K at 30 Hz with any version of the protocol and 4K at 60 Hz requires DisplayPort 1.2 or later.
But, as you wrote, anything should be sufficient if your goal is just to get access to the computer (e.g. to make a backup or migrate it to a new computer) in the event of an internal display failure.
I assume something like the Dell E2020H would work, with appropriate cable?
My Mom got her iMac back, with a new display AND a new logic board. They only charged her for the logic board. Several system preferences were lost (including the saved password for her email account in Apple Mail?). Re-entered it and all is well…but there is one WEIRD new symptom I can’t figure out:
When we turn the iMac on, the startup chime plays, BUT the display remains black for at least 35 seconds. My stopwatch counted 37, but I am deducting a couple seconds to account for my reflexes. Then the Apple logo appears, booting proceeds, and everything seems to work just fine.
I’m thinking we should call Apple back on this. Has anyone ever seen anything like this following logic board replacement? I should probably back it up again if they want it back.
It should. Use its DisplayPort interface to connect it to your iMac with an appropriate cable to connect it to your Thunderbolt port.
Double check your system settings. Especially the Startup Disk. Make sure it is set to your boot device and isn’t set to something else (or left unset), because that will cause it to take some time to search for a bootable device before starting.