How to connect a Samsung C27F390FH monitor to my Mac mini’s USB-C port?

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How to connect a Samsung C27F390FH monitor to my Mac mini’s USB-C port?

I am trying to figure out how to connect a hand-me-down Samsung C27F390FH monitor to my Mac Mini’s USB-C port. What I have right now is a VGA cable attached via an adapter to a USB-C port on the Mac. I have plugged the VGA cable into the back of this Samsung monitor. But I am not getting any response from the Samsung monitor. All I get is a floating dialog box that says check signal cable. Can I connect this particular Samsung monitor via VGA to a USB-C port on a Mac?

The Samsung monitor has both D-sub and HDMI ports. As recently as two days ago the monitor worked in HDMI for someone else. For the moment, though, I want to use VGA. One reason is that I have an adapter for USB-C to VGA. I do not have an adapter for USB-C to HDMI. The other reason is that I am not yet sure where the problem lies. I am replacing another monitor that is only VGA. It started failing last week. I have read at least four threads in MacRumors that the Mac can have problems with external monitors plugged into an USB-C port. I have to consider the possibility that the problem might not be in one monitor or the other. I wonder if the USB-C to VGA adapter has gone bad. Or is something off in the Mac OS?

This is why I ask about the Samsung C27F390FH. I need to see if I can rule it out.

[Re-Titled by Moderator]

Mac mini, macOS 12.3

Posted on Apr 29, 2022 7:29 AM

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Answer 1

Top-ranking reply

Mal-S

Level 5

4,984 points

Apr 29, 2022 8:23 AM in response to R_55a

I have a M1 iMac with Monterey (with two ports) and have successfully had a legacy VGA display connected to the USB-C port using a low cost USB-C to VGA adapter. I am currently using a legacy DVI monitor as my extended display with a USB-C to DVI adapter.

So both VGA and DVI do work with simple adapters.

I would first try turning the USB-C plug 180degs in the port and if that doesn't help try a different adapter.

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Answer 2

R_55a Author

Level 2

258 points

Apr 29, 2022 11:30 AM in response to Mal-S

In System Preferences>Display this second monitor appears as the Extended display. Its Desktop appears in the Preference. The Resolution setting is Default for Display. Color Profiles is C27F390. Rotation is Standard. All looks correct in System Preferences>Display.

Once, a few minutes ago when I awoke the Mac from sleep, this monitor flashed an image. Most likely a desktop photo. But the image was gone in a second.

The External Display is not showing what the System Preference is sending it.

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Answer 3

lllaass

Level 10

210,459 points

May 1, 2022 3:45 AM in response to R_55a

Look for a bent pin(s) on the connecting cable, I had that happen a month ago. If a pin get a little bend, it can be completely bent over when you connect a cable. Depending upon what pin is bend/not making contact, the monitor may work or not work. Also, the completely bent pin my contact an adjacent pin causing monitor not to work.

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Answer 4

May 1, 2022 4:26 AM in response to R_55a

Mac OS and USB-C ...one would think they'd be perfect, but my experience thus far has been there is lacking seamless support.

However, you CAN use USB-C connection and achieve a higher resolution with HDMI than you would if you were to use VGA/DVI. Two options either a dongle/hub (can be expensive and clunky I find) OR a USB-C to HDMI cable, I'd recommend the cable

but be sure to get at the one that says 60 Hz as otherwise you'll see degraded quality in picture.

Amazon.com: BlueRigger Premium USB C to HDMI Cable (6ft, 4K 60Hz, Braided, USB Type C) – Thunderbolt 3 Compatible with MacBook Pro/Air, iMac, Chromebook Pixel, Samsung Galaxy/Note, Dell, Surface Book : Electronics

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Answer 5

R_55a Author

Level 2

258 points

May 2, 2022 2:43 PM in response to Xarcabard

I suspect now the USB-C to VGA adapter. I used a HDMI cable to connect the Mac's HDMI port to the HDMI port on the new monitor. It worked. In fact, I was much impressed by the improvement in the image over that of my twelve-year old DVI monitor.

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Answer 6

R_55a Author

Level 2

258 points

May 5, 2022 12:10 PM in response to Mal-S

I am still futzing around with the equipment that I have. I reversed the VGA cable. No change. I unplugged and replugged the USB-C adapter into the Mac. No change. I check the cable connections every time I try something. The connectors appear secure. I see no deformation in the pins of the cable and the adapter.

Just now I unplugged the adapter and shut down the Mac. I replugged the cable and restarted the Mac. This time the Desktop on the second monitor appeared simultaneously with the log-in window in the main monitor. As soon as I typed in my password, the main monitor went to the Desktop and the second monitor went dark. Then the second monitor flashed its Desktop for a second and went dark again. It remains dark as I draft this post.

It may be significant that the System Preference for Displays shows the separate Desktops for the two monitors. In the main monitor I see the Desktop, but I do not see the one in the second monitor. When I unplug the USB-C adapter, this Preference does not show a second monitor.

I would not think that the Display System Preference would show the second monitor if I had a hardware problem. Now I suspect a software problem somewhere.

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Answer 7

R_55a Author

Level 2

258 points

May 11, 2022 8:59 AM in response to Xarcabard

I gave up and spent money. I bought a new HDMI cable for the new monitor and a USB-C to DVI adapter for the old monitor. Both work well.

As an aside I am much surprised at how faded is the display on the old monitor. After twelve years these monitors do get old.

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Answer 8

R_55a Author

Level 2

258 points

Apr 29, 2022 8:44 AM in response to Mal-S

I turned the USB-C plug over. No change.

Maybe I'll have to spend some money on something.

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Answer 9

Rudegar

Level 10

173,832 points

Apr 30, 2022 3:11 PM in response to R_55a

sounds like a bat connector or adaptor if it was me then I would test it with the setup of a friend or relative to verify if your mac is the culprit or if it's the adaptor or monitor

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How to connect a Samsung C27F390FH monitor to my Mac mini’s USB-C port?

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