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

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
 

Em St

macrumors newbie
May 31, 2020
21
11
Same issue here. Went back to Mojave, it works well. Once though I had the same problem with HDMI. Did you find a resolution.
 
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Em St

macrumors newbie
May 31, 2020
21
11
Did you disable all sleep options?

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
 
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filbert42

macrumors member
Jul 20, 2014
53
6
Worcestershire, UK
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
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:
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macfix17

macrumors newbie
Original poster
Apr 14, 2017
19
3
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 :(
 
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Em St

macrumors newbie
May 31, 2020
21
11
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 :(

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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macfix17

macrumors newbie
Original poster
Apr 14, 2017
19
3
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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dougpy

macrumors newbie
Sep 17, 2008
1
0
Same issue. Hard to believe they would ship an OS without checking external monitors.
 
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macfix17

macrumors newbie
Original poster
Apr 14, 2017
19
3
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?
 
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macfix17

macrumors newbie
Original poster
Apr 14, 2017
19
3
Well that's great news, now we have a working HDMI at last!
 
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Em St

macrumors newbie
May 31, 2020
21
11
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.
 
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macfix17

macrumors newbie
Original poster
Apr 14, 2017
19
3
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
 
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tgoecke

macrumors newbie
Jul 19, 2009
14
3
can't confirm Big Sur 11.2.1 fixes Mac mini HDMi problem, still does not recognize new 4k HDMI Monitor
 
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tgoecke

macrumors newbie
Jul 19, 2009
14
3
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?
 
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