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How to convert your old Mac into an external monitor using Luna Display
Repurposing Your iMac: How to Use It as an External Display
iMacs are renowned for their high-quality displays, and even after their computing days are over, that screen doesn’t have to go to waste. There are two effective ways to convert your iMac into an external display:
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Luna Display
This is a software-based solution that allows you to use a functional iMac as a secondary display. It’s ideal if your iMac is still operational and running a supported operating system. (continue read
To learn how to set up Luna Display, continue reading this blog.
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Display Driver Board
Perfect for iMacs that are no longer functional or are running outdated operating systems. This method involves opening the iMac and replacing internal components to directly connect the screen to another device.
Enhance your workspace with Luna Display’s Computer-to-Mac Mode, enabling you to extend your display to any Mac. Looking for a larger screen setup? Repurpose an additional Mac as a second or extended display for your primary Mac or PC. Breathe new life into your Older Macs by using them as external monitors. This mode supports various combinations of Mac models, including:
- iMac + MacBook Pro
- iMac + Windows PC
- MacBook + MacBook
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Mac mini + MacBook (using the MacBook as the main display for the Mac mini
Minimum Requirements
- Luna Display (USB-C)
- Primary Computer
- Mac running macOS 10.13 (High Sierra) or later
- Or a PC running Microsoft Windows 10 64-bit, Build 1809 or later
- Secondary Mac (to be used as external display)
- Fully functional Mac running macOS 10.13 (High Sierra) or later
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Optional but highly recommended for performance
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USB-C to USB-C Cable  Buy now! For Mac, PC |
Ethernet  Buy now! For PC only |
Step 1: Plug in your Luna Display
Once you have your Luna Display, you’ll need to take the dongle and plug it into your primary Mac or PC.
The Luna Display dongle must be plugged into a USB-C port that supports Thunderbolt or Display Port. While most Mac USB-C ports offer this compatibility, there are exceptions with the M-series Mac Mini and Mac Studio. On these devices, only the USB-C ports on the back support Thunderbolt or Display Port, whereas the front ports do not. For PCs, the situation is less straightforward. To ensure compatibility on a PC, make sure to plug the dongle into a USB-C port labeled with a Thunderbolt or Display Port icon. See the chart below for examples.
Supported USB-C ports
Step 2: Connect your iMac to your computer using a cable
While Luna Display does support Wi-Fi connections, we strongly encourage you to use a cable connection when using the Old Mac as a display. Driving the 5K iMac as a monitor requires a lot of bandwidth, so you’ll get the most reliable and consistent performance when wired.
Connecting your Old Mac using a cable to another Mac
Connect your secondary device (Old Mac) to your primary device using a USB-C to USB-C cable or an Ethernet cable for best results.
Connecting your Old Mac using a cable to PC
Unfortunately, USB cables cannot be used with Mac to PC setup. Luna display recommends using an Ethernet cable. Plug the ethernet cable into the secondary Macs ethernet port (incase it does not have the ethernet port, you can use an Ethernet to USB-C adapter
)and then plug the other end directly into your PC’s ethernet port.
Step 3: Download and launch the software
All the necessary hardware is plugged in now, so the final step is to load up the necessary software on your computers:
1. On your primary Mac or PC, download and open the primary Luna Display app
2. Next, on your secondary Mac, download and launch the Luna Secondary app.
Step 4: Use your Old Mac as a monitor!
At this point, your secondary Mac and primary computer should automatically detect each other and the secondary Mac should be configured as a monitor!
There are a few more settings you should configure. In particular, highly recommend enabling Retina Resolution so you get a crisp picture!
That’s it! 😄 You’re all done. You can now enjoy your old Mac as an external monitor.
Luna display allows you to also use your iMac as normal when you quit the luna display app.
If you need extra help in understanding the process or have other inquiries, please feel free to reach us helpdesk@macfixit.com.au
