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HDMI to external monitor not working unless plug/unplug on Mac Mini 2020

M

macfix17

macrumors newbie
Original poster
Apr 14, 2017
19
3
I am connecting a brand new Mac Mini (2020) via its HDMI (2.0) connector with a HDMI to DVI cable to an 1080p external monitor on Catalina 10.15.4.

The display shows a black screen and the only way to see the image is to disconnect the cable from either end (HDMI or the DVI) and connect it again once the computer is on (and the Mac OS welcome screen shows up) - then the image appears and all works fine (even in sleep mode - it awakes as it should showing the image again).

Is this a Catalina problem and is there a way to fix it or make it work?

I have tried resetting the SMC but nothing - the monitor works perfectly with my other older Macs so the problem is not there.

Thanks for your help
 
Same issue here. Went back to Mojave, it works well. Once though I had the same problem with HDMI. Did you find a resolution.
 
harriska2 said:
Did you disable all sleep options?
Click to expand...

no, I did now though.

So now I am on Mojave, yesterday I was interested in checking out the beta release of Catalina 10.5.16, I went to apples site downloaded a beta utility, didn’t figure out what to do, left it like that.

Then I wanted to remove the red notification about software update, as I am not going to Catalina, searched the forum, applied a few commands and notifications was gone.

Now, this morning, I was having the exact same HDMI issues in Mojave now! HDMI would not work if I don’t remove the other 2 TB3 monitors and restart...

Restored a backup from earlier yesterday and now I am good. So it seems something between my backup and fiddling with what I mentioned above is probably a root cause of the problem
 
macfix17 said:
I am connecting a brand new Mac Mini (2020) via its HDMI (2.0) connector with a HDMI to DVI cable to an 1080p external monitor on Catalina 10.15.4.

The display shows a black screen and the only way to see the image is to disconnect the cable from either end (HDMI or the DVI) and connect it again once the computer is on (and the Mac OS welcome screen shows up) - then the image appears and all works fine (even in sleep mode - it awakes as it should showing the image again).

Is this a Catalina problem and is there a way to fix it or make it work?

I have tried resetting the SMC but nothing - the monitor works perfectly with my other older Macs so the problem is not there.

Thanks for your help
Click to expand...
I’m also having problems with the hdmi display on my 2018 Macmini since the latest update. There are a few threads about the issue. Some say resetting nvram helps but I can’t confirm this as it seemed to work the first time I tried it but not this time.
 
Last edited:
Hopefully this is a software related problem as I just bought my new Mac Mini and it only works when I let it start and then unplug/plug the cable. I have tried unplugging it before I start the computer and then plug it once it has started (welcome login page on Mac OS) but nothing... I have to start it with the cable on and then unplug/plug and it works all through the day (even in sleep mode).

Really annoying to have this problem due to the software :(
 
macfix17 said:
Hopefully this is a software related problem as I just bought my new Mac Mini and it only works when I let it start and then unplug/plug the cable. I have tried unplugging it before I start the computer and then plug it once it has started (welcome login page on Mac OS) but nothing... I have to start it with the cable on and then unplug/plug and it works all through the day (even in sleep mode).

Really annoying to have this problem due to the software :(
Click to expand...

In my experience in the past few days I feel it is a the Adapter firmware that Catalina installs. I was able to figure out a workaround and it has been working fine since yesterday.

Have a look at: https://forums.macrumors.com/thread...-after-os-upgrade-patch.2221573/post-28536967
 
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Thank you very much for the answer with the info Em St,

As other people are asking - is there any way to replace the driver without having to install Mojave?

Thanks
 
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Same issue. Hard to believe they would ship an OS without checking external monitors.
 
It seems Big Sur fixes this issue (looong after it should have been addressed):

Big Sur 11.2:
macOS Big Sur‌ 11.2 improves Bluetooth reliability and fixes the following issues:
- External displays may show a black screen when connected to a ‌Mac mini‌ (‌M1‌, 2020) using an HDMI to DVI converter

Could any of you using Big Sur 11.2 confirm this works?
 
I have 3 monitors. 1 HDMI with 2 TB @ 4k60hz. After the update, shutdown and turn on. It worked the first time, all monitors, the second time, the HDMI was black. This was the same before the update as well.
 
Hi Em St,

Then we still have the same problem - could you please report back with any new findings (if things finally work or if it's still the same)?

If more people can chime in to let us know if it works for them it would be really helpful.

Thanks
 
Solution: setting the LG 27UL850 4K display in display settings to DisplayPort Version 1.2 solved the issue.
But the question remains: why do I have the display working with DisplayPort Version 1.4 after an NVRAM reset?
 
I have a new Mac mini bought this year with the latest version of Big Sur and have to unplug/plug in HDMI cable when Mac is coming out of sleep, but not every time so definitely fixed in latest version of Big Sur.
 
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