Mac Mini 2018 HDMI failes after OS upgrade / patch

[theunk]

I purchased a UGREEN HDMI to DVI adapter cable to replace the HDMI to DVI adapter. This eliminates the HDMI to HDMI connection at the DVI adapter. Should it matter? Well I can once again use dual monitors and they respond as independent displays, correctly identified and configured by the OS.
I hope the 11.4 update fixes everyones HDMI display issues.

 

[sbleon]

I have a 2018 Mac mini (Intel, of course) with two monitors. One is a 4k Dell plugged in via HDMI cable to the HDMI port on the mini. The other is an older Dell plugged in via a USB-C-to-HDMI adapter and an HDMI-DVI cable. Ever since upgrading to Big Sur, I've had problems getting both monitors to work. With both monitors plugged in, the 4k monitor stays black on boot and after I log in. I was able to workaround this by unplugging the USB-C-to-HDMI adapter, booting, logging in, then plugging the adapter back in. That got both monitors working, but was a real pain.

I think I finally have a more reasonable workaround, though. Yesterday, I worked with Apple support on this and they had me delete my windowserver preferences files, located at:
/Library/Preferences/com.apple.windowserver.plist
/Users/[me]/Preferences/ByHost/com.apple.windowserver.*.plist

Then, they had me shutdown and reset NVRAM (holding Option-Command-P-R for two chimes). This fixed the problem temporarily, but if I restart or let the computer sleep I will lose the 4k monitor again.

Even without the preferences files, restarting seems to always leave me with one monitor. However, shutting down and cold booting seems to result in both monitors working (after I log in, anyway).

So, my recommendations are:
1. Shutdown and power on again instead of restarting
2. Set your Energy Saver prefs so the computer doesn't go to sleep. (Display sleep seems to be OK.)
3. Delete the preferences files I listed above if necessary.
4. Reset your NVRAM if necessary.

 

[tstimper]

Its interesting to see that this issue was fixed for some people with BigSur and came back for others with later updates.
I really think the the cause of this issue could be the firmware version which Apple uses for the MCDP2920A4 (
DisplayPort1.4 to HDMI2.0a protocol converter with HDCP2.2 repeater).
Many USB-C to HDMI Adapters, which are suggested by some as workaround are using the same MCDP2920A4 Chip as Apple uses in the Mac mini 2018 and the Mac mini M1. And for some of this adapters firmware upgrades are available.

Is anyone able to find out, which MCDP2920A4 firmware version Apple uses?
And has anyone a history list / bug list for MCDP2920A4 firmware?

This chip is also used in the Apple TV 4K 2021. It would be interesting if anyone has tried to use an HDMI to DVI Adapter with Apple TV 4K 2021 ans see similar issues.
Next question would be, does Apple use the same firmware for the chip in all these devices.

 

[theunk]

I am commenting across 2 threads. If I should not, please let me know.

My HDMI port has been working well since June. My issue since then has been getting consistent dual monitor support. Very unstable.

Sept 21 8:57PM For some time now I have used only a single display. This morning I was in a GoToMeeting and turned on my second monitor that is connected Thunderbolt > HDMI. Both displays were cycling on/off to to the point I powered off the TB >HDMI display. Today I got a software update nag for the Safari 15 update. I installed it and now the TB>HDMI display connection is dead.
HDMI still works.
Sept 22 11:49PM Tonight I turned on the TB connected display. Nothing - no signal. I just left it on and got doing other things. About an hour later the display is active working fine. I will leave it run all night and see what it looks like in the morning.

 

[theunk]

I have updated to Monterey 12.0.1 and have dual monitors, 1 HDMI>HDMI and one TB3>HDMI
So far 24 hours stable.
?

 

[MylesTheGray]

Hello,

I’ve been struggling with mainly display issues since purchasing my fully specced out Mac mini in April 2021.

Computer won’t wake from sleep and drive displays - turned off sleep. Turning off sleep has not fixed the issue. Terrible Bluetooth. Terrible wifi. Bought new apple mouse and keyboard but it didn’t work. Now I run wired everything.

My 2012 laptop is an upgraded beast and I still use it without issues. I’m stunned that I’ve had so many problems with my 2018 Mac mini. I would have immediately returned it but as it’s a custom build I cannot. In the first month the computer had the logic board replaced.

Displays will black screen randomly or upon restart. I usually have to fiddle with cables and then do a hard restart or similar. Sometimes purple or green lines appear. Yes, I’ve tried smaller cables in length, new cables, different adapters, etc etc.

(1) 4k Samsung TV plugged into HDMI
(1) ASUS 4k display plugged into Thunderbolt via LMP adapter.

I found a third party app that fixed the display from wake problem - MonitorControl (pretty cool app for other reasons too).

At this point my computer is somewhat usable if I don’t turn it off but any time a restart is needed it won’t work. Sometimes I’ll get caught in an install loop because computer won’t restart correctly. Sometimes displays will reconfigure resolution and act wonky.

Computer has gone back to repair shop for the third time but they state that there are no issues with displays when upgrading to Monterey. However, my Universal Audio gear for music production is not yet supported for Monterey so I did not update to it myself.

Furthermore, Apple authorized service shop can’t test my computer correctly as they don’t even have (2) 4k monitors to test machine. I plan to eventually run (3) 4k display but now I doubt that will even work. They insist that the computer be fully updated and will not test computer in Big Sur, Catalina, or Mojave. So, in turn Apple will not open a support ticket as service techs cannot find a problem.

Only solution I have found is running Mojave as it’s the only stable OS X for my machine but it lacks key features I use on the daily. Dual boot seems silly and considering the cost of equipment. I’ve done fresh or clean installs without file transfers. Experimented with file vault on or off. Nothing seems to work.

I am quite upset that I paid $4000 CAD for a computer that didn’t work right out of the box - really kicking myself for not researching the product more, my ignorance, and trusting Apple’s products to be what they used to be - solid and reliable.

Apple support has been terrible, they have taken lots of information but have no explanations or fixes. Service shop can’t do anything either. This forum thread educated me more then apple or service team - so for that, thanks to all who have contributed.

If Monterey actually works for driving my displays then I will be extremely happy. However, waiting 7 months for my computer to be truly usable is unacceptable in my eyes. Customers with these problems deserve to be compensated.

Thanks for reading my rant. My next setup will probably be Linux as I’ve lost trust in Apple.

Question: have most display issues been resolved with Monterey?

Edit: typos

 

[theunk]

Myles,
My display issues since the Monterey update have been pretty well non-existent. I have no experience connecting to a TV. I have 2 older displays - a Dell 24” and a LG 27”. Most of my issues have been relating to using dual displays. For awhile my HDMI output was flakey, but thunderbolt was constant. During those times I recall having wakeup issues. I should go back and create a log, but once the problem goes away I lose interest. I do notice that if I power off either or both displays there is a slight lag before the display is fully functional.
I have eliminated the hdmi to dvi adapter for the Dell, the transition is done in a cable. I do use a TB3>HDMI adapter for the LG. The TB3>HDMI cable I have hs a longer HDMI connector that may put unnecessary strain on the port. Also, I only power my mini down when I have to.
So today, my 2018 i3 8Gb 128GB continues to operate exceptionally well.
There has not been any activity on this thread since Monterey, so maybe Apple has figured it out.

This article deals with multiple displays. https://www.macrumors.com/2020/11/24/m1-macs-able-to-run-six-external-displays/

 

[MylesTheGray]

Hello,

Sorry the delay. I picked up the computer from shop after they mentioned no issues with computer when updated to Monterey. Note: shop did not have enough 4k displays to test computer.

Display to cable configuration:

ASUS VP28U - Stock HDMI cable to LMP HDMI to USB C Adapter

Samsung ULED TV 65” - HDMI Cable 15feet(4.5meter), 4K HDMI Lead-Snowkids 18Gbps HDMI 2.0 Cable 4K@60Hz direct into Mac Mini (HDMI Cable 15feet(4.5meter), 4K HDMI Lead-Snowkids 18Gbps HDMI 2.0 Cable 4K@60Hz, 3D Support, Ethernet Function, Video 4K UHD 2160p, HD 1080p, 3D - (for Fire TV, for PS3/4, for Netfilx) https://www.amazon.ca/dp/B07M65ZB5W...t_i_JW6980N51ZSX4HDJT5YF?_encoding=UTF8&psc=1)

——

Computer still having intermittent issues with large Samsung display and ASUS Display.

Asus: display takes a long time to turn on or get connection. I have to boot computer and use Samsung TV to input login details and then ASUS display turns on when OSX has fully booted after user/password login.

Samsung: the HDMI connection seems to be reliable for the most part but every once and a while it won’t work on boot up or restart resulting in me reconfiguring cables and hard restarting computer.

——

Monterey - big improvement on how OSX handles displays and now my computer seems to reliably boot with functional HDMI port. However, as of now - ASUS screen is operational but Samsung TV will not pick up information from MAC Mini. Note: issue seems to be better in Monterey. Before, I would dread any type of computer restart as it would not reliably boot. Monterey seems to work 6/10 times. For now, computer won’t be turned off.

Computer still has problems waking displays up unless I use third party app. So, for now I have prevented the displays from sleeping and just turn off ASUS when not in use.

Yes, the cable for the TV is longer then 3ft but the Mac Mini has been branded as a device to run a home theatre system. Some people have rack equipment far away from the screen. HDMI cables are quite capable of long cable runs. Note: changing to smaller cable and placing Mac Mini near TV does not seem to help.

Thoughts?

Edit: I’ve since done more testing and the ASUS display does not work using the smaller 3ft HDMI cable that came with my ASUS monitor plugged directly into the HDMI port and nor does the HDMI port work with my Samsung TV.

I believe the HDMI ports are the problem as I am rubbing both displays without issues while using LMP adapters.

 

[tstimper]

Does anybody know if any version of BigSur or Monterey does update the firmware on the internal
MCDP2920A4 (DisplayPort1.4 to HDMI2.0a protocol converter with HDCP2.2 repeater)?

 

[theunk]

Does anybody know if any version of BigSur or Monterey does update the firmware on the internal
MCDP2920A4 (DisplayPort1.4 to HDMI2.0a protocol converter with HDCP2.2 repeater)?

You have asked this a number of times. If you can tell how I can verify which version I have in my 2018 Mini I am happy to share.

 

[arions]

Does anybody have a brand new Mac mini 2018 without any updates?

I had Monterey on a 13 month old mini the day before yesterday, when I bought it and had no idea about this problem. Yes I met the problem, no picture on LG W2242T after boot, so I plugged it to my Samsung smart tv, where it worked fine. And downgraded immediately to Catalina 10.15.7 because I needed that for several reasons. I figured out the unplug-plug solution, it works fine, but I am afraid to damage the connector if unpluging and pluging it daily more times. I am thinking about never shooting the mini down. Apple asked me to contact LG to exclude some incompatibility on their side with this old monitor. I hope there will be some solution, unfortunatly my service coverage expired in November.

 

[TimManzana]

I got a Mac mini 2018 i7 since September and have only used it a handful of times due to this very issue, I don’t have a computer monitor so I have it connected to a 75” Sony TV, and the damn thing works half the time, using straight hdmi to hdmi.
From what I’m reading downgrading to the older OS is the only workaround?

 

[robotica]

I got a Mac mini 2018 i7 since September and have only used it a handful of times due to this very issue, I don’t have a computer monitor so I have it connected to a 75” Sony TV, and the damn thing works half the time, using straight hdmi to hdmi.
From what I’m reading downgrading to the older OS is the only workaround?

Just get a USC C to HDMI adapter

 

[TinHead88]

Yes, unfortunately it seems Apple have done something weird with HDMI in recent years and it causes a lot of trouble. The answer is to avoid using the built in HDMI by using external converters. These cables are not expensive. Best solution for me has been to go with a USB C to Display Port cable but of course only some monitors support DP.

It's really disappointing Apple hasn't acknowledged these problems and worked harder to address them.

 

[Trevor.Sorrento]

I have this issue also. I am using an Apple Thunderbolt Display as my main display (USB-C adapter to Mini DisplayPort) and an LG TV connected to the HDMI port as the extended display. Just for fun I tried this and it worked:

1. Turn off Mac mini.
2. Unplug power cord from Mac mini for at least 30 seconds to reset PRAM.
3. Connect external TV to HDMI port (in my case an LG TV as extended display).
4. Power on the external TV.
5. Disconnect primary display from Mac Mini.
6. Connect power cord to Mac mini.

At this point the LG TV is on and connected to the Mac mini and waiting to be recognized as the only display available.

7. Turn on Mac mini.
8. LG TV is recognized as main display.
9. Reconnect Thunderbolt Display as extended display.
10. Reassign main/extended displays as desired in System Preferences.

I know after talking to Apple, and taking mine in for investigation at an Apple store, that there is an issue with the controllers and firmware for the HDMI port.

Hope this helps somebody out there ?

 

[TimManzana]

I have this issue also. I am using an Apple Thunderbolt Display as my main display (USB-C adapter to Mini DisplayPort) and an LG TV connected to the HDMI port as the extended display. Just for fun I tried this and it worked:

1. Turn off Mac mini.
2. Unplug power cord from Mac mini for at least 30 seconds to reset PRAM.
3. Connect external TV to HDMI port (in my case an LG TV as extended display).
4. Power on the external TV.
5. Disconnect primary display from Mac Mini.
6. Connect power cord to Mac mini.

At this point the LG TV is on and connected to the Mac mini and waiting to be recognized as the only display available.

7. Turn on Mac mini.
8. LG TV is recognized as main display.
9. Reconnect Thunderbolt Display as extended display.
10. Reassign main/extended displays as desired in System Preferences.

I know after talking to Apple, and taking mine in for investigation at an Apple store, that there is an issue with the controllers and firmware for the HDMI port.

Hope this helps somebody out there ?

Thank you, I ended up grabbing a cheap USB-C to HDMI adapter and is working ok so far.
ill keep an eye to IF they ever address the straight HDMi connection so switch it back at some point. Thank you.

 

[TimManzana]

Just get a USC C to HDMI adapter

did that and working ok so far thanks

 

[TimManzana]

Anyone knows if this has been fixed with the latest update? I ended up factory resetting the mini and storing it to put it for sale, but don’t want the future owner to have this issue and think the computer is broken later down the road. Thank you.

 

[MylesTheGray]

My 2018 Mac mini is working alright with Monterey now.

However, computer will randomly lose resolution, not boot correctly with displays, and gets stuck in screensaver.

 

[Trevor.Sorrento]

I don't think the latest update has fixed this, certainly not for me. I am up to date with Monterey 12.2.1 and my previous workaround no longer works. I am now using a USB-C to HDMI adapter for the external display. However I need every one of the connections on my Mac mini for peripherals, so I really want to get the HDMI port working. If I buy a new Mac mini I don't have enough outputs.

For what it's worth, the tech (genius) that looked at my Mac mini told me the problem was due to the default resolution setting in the HDMI port controller. The controller resolution at start up doesn't match the resolution of my TV and so the TV is not detected. Because it is not detected I can't see the TV in System Preferences and therefore can't change the TV resolution.

 

[MylesTheGray]

It’s been almost a year since I dropped 4k CND on my Mac mini for music production and the display issues haven’t truly been fixed.

 

[Trevor.Sorrento]

Is there anyone out there with a 2018 Mac mini running Monterey that IS able to use the HDMI port?

 

[MylesTheGray]

Is there anyone out there with a 2018 Mac mini running Monterey that IS able to use the HDMI port?

I am - but it’s flaky. Samsung 65” TV and 5ft cable.

Computer won’t run three monitors either.

 

[Trevor.Sorrento]

I am - but it’s flaky. Samsung 65” TV and 5ft cable.

Computer won’t run three monitors either.

Sounds like we may be dealing with a marginal design that only just works. Could you describe what is going on when it stops working, and when it starts working again?

 

[MylesTheGray]

Sounds like we may be dealing with a marginal design that only just works. Could you describe what is going on when it stops working, and when it starts working again?

I won’t post my equipment again as it’s a length previous comment.

Computer will not show display on boot via HDMI port and sometimes the USB C adapter will flake out as well.

Randomly, the hdmi port display will stop working and when it appears again it’s usually ultra low resolution.

Computer gets stuck in screen saver and needs special keys to unlock screen.

————

Like I stated before - latest Monterey is far better then before. I used to fear restarting my computer.