Catalina & UHD/4K Monitor/TV

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Catalina & UHD/4K Monitor/TV

I upgraded my Mac mini 2018 from Mojave to Catalina, with it I use a Toshiba 43LF621U19 Monitor (a 43" UHD TV). The combo has worked well since I purchased them both last spring.

At first I thought the upgrade had failed, but suspected video problems, I swapped a Vizio HDTV into the HDMI port and the upgrade was waiting at the login prompt (in front of Catalina island). I then tried swapping the Toshiba back in and it worked. Everything else seemed fine, I was able to restart and the UHD monitor continued to work. However, if I shut the mini down and then power it back on, I get no video; I have to hard power it off, swap the Vizio back in, power it up and swap again at the login screen.

I've upgraded the Firmware on the Toshiba and played with Default and Scaled resolution, but no change. Does anyone have any suggestions for troubleshooting and getting this to work? Is there a terminal command I can use to see what display the Mac is 'seeing' and what resolution it's sending?

Thanks for any help.

Edit: I have also tried re-installing Catalina, while it seemed to go through some additional steps (typical first time stuff), in the end the problem persists.

Mac mini 2018 or later

Posted on Oct 9, 2019 7:01 PM

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Answer 1

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A07570 Author

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59 points

Oct 31, 2019 4:03 AM in response to A07570

I’m going to mark this thread solved, because installing the macOS Catalina 10.15.1 update fixed my problem. I had been using a workaround solution which is to use a USB-C to HDMI adapter and moving the monitor there. Since installing 10.15.1 I have now moved my Toshiba UHD TV/Monitor back to the HDMI port, I once again get full 4K resolution (as I did with Mojave), and I can power the system down (something I couldn’t do with 10.15).

I would recommend anyone still having this problem after installing 10.15.1 to follow the thread I linked above, as this has not solved the problem for everyone — I actually have no idea what percentage of 4K TVs/Monitors had this problem in the first place, and what percentage remains ‘crippled’. But something is unique enough about my mini 2018 and Toshiba 4K monitor, that I had the problem with 10.15 and it’s gone (or unnoticeable) with 10.15.1. Obviously Apple still has some work to do.

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Answer 2

mlweb

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4 points

Oct 31, 2019 8:44 AM in response to A07570

Using an alternative cable USB-C (Mac Mini 2018) --> Display Port (Samsung U28E850 4k), works with 10.15

SMC Reset
NVRAM Reset
Update to 10.15.1
Boot first time after finishing update with alternative cable USB-C --> Display Port
Shoot down
Change cable HDMI (Mac) --> HDMI1 30Hz (Samsung U28E850 4k): works also by starting, login and after login
Shoot down
Change same cable to HDMI2 60Hz, works also by starting, login and after login

Good luck.

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Answer 3

A07570 Author

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59 points

Oct 10, 2019 8:04 PM in response to A07570

Here's a command related to this question above "Is there a terminal command I can use to see what display the Mac is 'seeing' and what resolution it's sending?"

system_profiler SPDisplaysDataType |grep Resolution

This command string returns the "active resolution" of the current display (not its maximum resolution). On my monitor it returns:

system_profiler SPDisplaysDataType |grep Resolution

Resolution: 3840 x 2160 (2160p/4K UHD 1 - Ultra High Definition)

So, the mini and Catalina are seeing the correct resolution, it just can't seem to set it correctly from a cold start. There should probably be another command that returns more information about the display's manufacture, model, and capabilities; I'll keep looking for that.

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Answer 4

A07570 Author

Level 1

59 points

Oct 10, 2019 9:17 PM in response to A07570

Apparently there's a well attended thread on this problem already; while there's no exact solution yet I'll follow there.

https://discussions.apple.com/thread/250715830?page=2

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Catalina & UHD/4K Monitor/TV

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