2018 mac mini - Blank screen on wake from sleep

pumpkinwhite

macrumors member
Original poster
Sep 3, 2006
54
34
Hi - I just received my 2018 i5 mac mini a few days ago. I've been having problems with it displaying anything after waking from sleep. Every time I wake up the computer from sleep, the monitor is blank. The monitor backlight comes on when I wake the computer, but it's just a backlit black screen. I keep on trying various keys on the keyboard, or mouse and eventually it displays the screen. That too, not always. Sometimes even despite trying for 5-10 minutes the screen stays blank. I just have to force restart the computer.

I am using Acer monitor XB271HU, and have it connected via HDMI. I does seem like it's trying to perform the HDMI handshake but fails. Cause every time I press a key on the keyboard or mouse, the screen flickers or the backlight goes off and on for a quick moment. But most of the time the screen stays blank. I've had this monitor for over a year now, and never had this problem with my previous computer. So I am pretty sure it's not the monitor. The monitor does have a 'Deep Sleep' setting, which I have set to OFF.

Things I've tried so far -
1. Tried with a different HDMI cable.
2. Reset the computer's NVRAM by pressing Alt-CMD-P-R on start-up
3. Reset the SMC by simply shutting it off and taking out the power cable.

None of these things seem to work. Is anyone else experiencing this issue? Any solutions? Thanks.
 
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coot

macrumors member
Jun 30, 2005
45
2
UK
I've had this quite a bit too.

Just updated the firmware on my LG 38UC99 and will see if that makes any difference.
A double shame with the new always on LED that you cant tell if the machine has woken up or not...
 
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ncrypt

macrumors 6502
May 16, 2012
334
202
UK
Also have this same issue typically if I haven't been at my Mac for a few hours. Takes over a minute to wake the monitor (LG 27UD68 connected via USB-C to Displayport)
 
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pumpkinwhite

macrumors member
Original poster
Sep 3, 2006
54
34
Also have this same issue typically if I haven't been at my Mac for a few hours. Takes over a minute to wake the monitor (LG 27UD68 connected via USB-C to Displayport)
It happens to me even if I put the computer to sleep and then immediately try to wake it. I was guessing that it's an HDMI handshake issue with the HDMI port. And so was going to purchase a USB-C to Displayport cable. But you just confirmed that the issue exists for you even when you are using a USB-C to displayport cable. So perhaps I shouldn't waste money on another cable. I wasn't looking to use up a Thunderbolt 3 port for the monitor anyway. Not when I have HDMI in place. Seems to be an issue affecting other people too.
 
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coot

macrumors member
Jun 30, 2005
45
2
UK
For clarification I am using the USB-C cable to connect to my LG.

Been to sleep twice this afternoon has woken up the screen OK but still monitoring.
 
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bandits1

macrumors newbie
May 18, 2017
8
2
It happens to me even if I put the computer to sleep and then immediately try to wake it. I was guessing that it's an HDMI handshake issue with the HDMI port. And so was going to purchase a USB-C to Displayport cable. But you just confirmed that the issue exists for you even when you are using a USB-C to displayport cable. So perhaps I shouldn't waste money on another cable. I wasn't looking to use up a Thunderbolt 3 port for the monitor anyway. Not when I have HDMI in place. Seems to be an issue affecting other people too.
I've experienced the monitor wake-up delay with both a Mediabridge HDMI cable and a Cable Matters USB-C-to-DP cable. It was occasionally worse with the USB-C-to-DP cable as my LG 27UK650-W was clearly on but remained completely blank like the OP reported, but there's still a relatively significant delay with the HDMI cable, too.

It appears to me that my monitor is being woken up twice by the Mac Mini -- the first wake-up happens as quickly as I'm used to but with a blank screen, then it goes right back into power-saving mode even though the Mac Mini is already fully spun up from sleep, then the monitor wakes up again several seconds later with the normal login screen. Maybe this has something to do with the T2 chip?
 
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MacWorld78

macrumors 6502
Jul 25, 2012
433
184
I had a quite similar issue with the HDMI connection but I'm glad I'm currently using a USB C to DisplayPort - work just fine for the startup or sleep mode.

try to take them out both side HDMI and re-connect make sure they are secure connections between male and female.
 
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djc6

macrumors 6502a
Aug 11, 2007
633
152
Cleveland, OH
I have two older 27UD58 displays that I use on Mac Mini 2018 and also 15" Mid-2017 MacBook Pro. Mac Mini is connected via HDMI & USB-C to HDMI 2.0 - laptop is connected via 2x USB-C to DisplayPort.

I used to have issues with these displays not waking up on my laptop.. Performing both PRAM and SMC reset fixed - not sure which did the trick. I didn't have issues after that.

i also noticed differences in wakeup time if I used touch-id button on laptop vs keyboard vs mouse.

I do have an issue on mac mini 2018 where I cannot wake up via keyboard - I have to press mouse button and it wakes right up!
 
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pumpkinwhite

macrumors member
Original poster
Sep 3, 2006
54
34
What happens if you unplug and replug the cable, then press the keyboard keys to wake it up?
Unplugging and plugging the cable, the monitor sometimes remains blank, while at other times it comes back up after a minute or so. One time it came back up instantly. Basically, there is no consistent behavior.
[doublepost=1542856629][/doublepost]
I had a quite similar issue with the HDMI connection but I'm glad I'm currently using a USB C to DisplayPort - work just fine for the startup or sleep mode.

try to take them out both side HDMI and re-connect make sure they are secure connections between male and female.
Thanks for the suggestion. I did make sure that the connection is secure on either side. I tried different cables too. It’s definitely not a cable or port issue.

Just to see if DisplayPort works any better I ordered a USB-C to DisplayPort cable. Will arrive in two days. Will report it that fares any better.

Something else to add in case anyone has the same monitor - I read somewhere that putting ON game mode in the monitor fixed HDMI handshake issues for someone. I tried that too. Didn’t help.
 
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MacWorld78

macrumors 6502
Jul 25, 2012
433
184
Unplugging and plugging the cable, the monitor sometimes remains blank, while at other times it comes back up after a minute or so. One time it came back up instantly. Basically, there is no consistent behavior.
[doublepost=1542856629][/doublepost]
Thanks for the suggestion. I did make sure that the connection is secure on either side. I tried different cables too. It’s definitely not a cable or port issue.

Just to see if DisplayPort works any better I ordered a USB-C to DisplayPort cable. Will arrive in two days. Will report it that fares any better.

Something else to add in case anyone has the same monitor - I read somewhere that putting ON game mode in the monitor fixed HDMI handshake issues for someone. I tried that too. Didn’t help.


Just for your information regarding the USB-C to DP

I'm using this cable:

https://www.amazon.co.uk/gp/product/B01EZH7CKO
 
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TheGreatDave

macrumors newbie
Jun 11, 2013
17
0
I have this issue with my LG 27UD68 if I use USB C to DisplayPort. HDMI seems to work fairly reliably.

I found that if I turned on accessibility voice over on the login screen I could tell the Mac had actually booted to the login, and when I type in my username and password the monitor will switch on soon after. So it’s certainly a software issue.
 
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tthkbw

macrumors newbie
Jan 13, 2009
24
20
Portland, OR
Unplugging and plugging the cable, the monitor sometimes remains blank, while at other times it comes back up after a minute or so. One time it came back up instantly. Basically, there is no consistent behavior.
[doublepost=1542856629][/doublepost]
Thanks for the suggestion. I did make sure that the connection is secure on either side. I tried different cables too. It’s definitely not a cable or port issue.

Just to see if DisplayPort works any better I ordered a USB-C to DisplayPort cable. Will arrive in two days. Will report it that fares any better.

Something else to add in case anyone has the same monitor - I read somewhere that putting ON game mode in the monitor fixed HDMI handshake issues for someone. I tried that too. Didn’t help.
I have a slightly different problem with a new P2415Q attached to a 2018 Mac mini via HDMI running at 4K 60Hz.

Everything runs perfectly and quality of picture is very good. However, the monitor takes 6-7 seconds to restart after going to sleep. I have verified that the Mac mini is not sleeping, but the monitor is. I see the monitor power LED fading in and out. When I hit a key to wake the monitor, it takes 6-7 seconds for the monitor to respond.

There is some variability in this. For example, if I put the monitor to sleep, then hit a key a few seconds later (but after the monitor has reported it is sleeping, and the power LED is fading), the response time is around 2 seconds. If I wait for 10 seconds or more, the response time is 6-7 seconds.

I am also considering buying a USB-C to Display Port cable and see if that changes anything. I look forward to the results of your test.
 
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Apple fanboy

macrumors Nehalem
Feb 21, 2012
36,184
24,938
Behind the Lens, UK
I have been running mine with a usb c to DisplayPort cable and haven’t seen this behaviour.
Tonight I’ve just added a BenQ SW271 which runs directly of the USB c cable as it has a USB port.
That seems to wake okay to.
 
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pumpkinwhite

macrumors member
Original poster
Sep 3, 2006
54
34
I've confirmed that the computer itself wakes up just fine upon hitting any keyboard or mouse key. Because I'm able to log in remotely via VNC screen sharing (from my iphone). If I continue logged in, the monitor comes back up after a couple of minutes.

Another small development - A couple of times upon waking up my mouse was frozen. I had to unplug and replug the mouse (I'm using a wired mouse which is connected to a usb c hub). I ignored it the first time, but it happening again on a consecutive day shows it was not a one-off behavior.
 
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Spectrum

macrumors 68000
Mar 23, 2005
1,563
894
Never quite sure
It appears to me that my monitor is being woken up twice by the Mac Mini -- the first wake-up happens as quickly as I'm used to but with a blank screen, then it goes right back into power-saving mode even though the Mac Mini is already fully spun up from sleep, then the monitor wakes up again several seconds later with the normal login screen. Maybe this has something to do with the T2 chip?
I'm pretty sure that is how my 2011 mini behaves when coming out of sleep when the screens are sleeping too (Dell U2711). Connections are mDP and HDMI. SO I'm not sure this is a new thing necessarily...
 
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bandits1

macrumors newbie
May 18, 2017
8
2
I'm pretty sure that is how my 2011 mini behaves when coming out of sleep when the screens are sleeping too (Dell U2711). Connections are mDP and HDMI. SO I'm not sure this is a new thing necessarily...
My 2011 Mac Mini died just a couple of weeks before this 2018 model came out, and the attached Benq monitor never, ever behaved like this. It woke up and showed the login screen just seconds after I heard the HD in the Mini spin up out of sleep.
 
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pumpkinwhite

macrumors member
Original poster
Sep 3, 2006
54
34
So my USB-C to displayport cable arrived today. And indeed the results are much better. The original problem doesn't seem to be there, though there is a different problem now. Computer doesn't go to sleep every time.

Here is the summary -
1. On HDMI - Upon waking from sleep, computer wakes up with blank screen. Usually takes minutes for image to come up (if it does). Disconnecting and connecting the HDMI cable usually fixes it (it may take a couple of tries). Sometimes USB mouse doesn't work on waking from sleep. Disconnecting and reconnecting fixes it.
2. On Displayport (via thunderbolt port) - Computer wakes up as expected, and monitor instantly shows image. However, computer doesn't go to sleep every time. Sometimes monitor just comes back up. It may take a couple of tries to put computer to sleep. No USB mouse freezing thus far, but that's inconclusive.
 
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mathism

macrumors newbie
Dec 5, 2018
1
0
I've experienced the monitor wake-up delay with both a Mediabridge HDMI cable and a Cable Matters USB-C-to-DP cable. It was occasionally worse with the USB-C-to-DP cable as my LG 27UK650-W was clearly on but remained completely blank like the OP reported, but there's still a relatively significant delay with the HDMI cable, too.

It appears to me that my monitor is being woken up twice by the Mac Mini -- the first wake-up happens as quickly as I'm used to but with a blank screen, then it goes right back into power-saving mode even though the Mac Mini is already fully spun up from sleep, then the monitor wakes up again several seconds later with the normal login screen. Maybe this has something to do with the T2 chip?
I have the same display and experience the exact same problem described in the second paragraph. Also, when I connect a LG 27UK850-W over the supplied USB-C cable, the MacMini sometimes kernel panics on wakeup. Kernel panics when using peripherals seem to be a common issue:
https://forums.macrumors.com/threads/2018-macbook-pros-crashing-with-bridge-os-error.2128976/page-58
 
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nyskifan

macrumors newbie
Jun 17, 2008
13
6
I have encountered the same issue. Dual DVI displays are slow to wake from sleep. Computer appears to wake instantly but displays take 20-30 seconds to turn on. HDMI->DVI cable turns on slightly earlier than USB-C->DVI cable. Both seem too slow.
 
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Fishrrman

macrumors Core
Feb 20, 2009
19,014
6,482
A question for the people having "dark displays" when waking from sleep:

What happens if you power off the display, and then power it back on?
Does it "liven up"?

If that seems to cure the problem, a suggestion (may help, or perhaps not):
1. Before you walk away from the Mini, reach forward and switch the display OFF
2. When you come back to the Mini, "wake it up" (move the mouse, etc.), then...
3. Reach forward and power ON the display.

I do this routine with my 2012 Mini, and it works well.
 
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ncrypt

macrumors 6502
May 16, 2012
334
202
UK
Also have this same issue typically if I haven't been at my Mac for a few hours. Takes over a minute to wake the monitor (LG 27UD68 connected via USB-C to Displayport)
I called Apple support regarding this issue and the first thing the advisor asked me to do was reinstall macOS and said if that didn't work then it can't be the software at that point...

She advised I just go to a store for a replacement unit if the reinstall doesn't work it.

Highly skeptical at how correct she is, this sounds exactly like a software issue.
 
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nyskifan

macrumors newbie
Jun 17, 2008
13
6
I have encountered the same issue. Dual DVI displays are slow to wake from sleep. Computer appears to wake instantly but displays take 20-30 seconds to turn on. HDMI->DVI cable turns on slightly earlier than USB-C->DVI cable. Both seem too slow.
My issue seems to have fixed itself. Display wake up up is back to normal now. I did install the 14.1.2 update in the interim.
 
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