Mac Mini - HDMI Monitor issue

[Jimmysb]

I am running a Mac Mini (M1) with Ventura (13.1), which I have only recently bought. Initially I had just a HDMI monitor connected, and when the system went to sleep after a while without use when re-starting sometimes the monitor was just "static" black and white dot flickering. A google search can up with some answers that included not letting the hard-drives shut-down, and this seemed to work. Yesterday I connected my VGA monitor via an approved adapter as well, and this morning the problem re-occurred, however, just on the HDMI monitor, and not on the VGA monitor.
The monitor and cable worked without issue on my previous system and my works laptop (both windows) without issue. Any advice would be appreciated, many thanks.

 

[Raz0rEdge]

You might want to swap the HDMI cable and see if the issue persists.

 

[Jimmysb]

You might want to swap the HDMI cable and see if the issue persists.

I changed the cable as suggested, now with the monitor (HP E202) supplied cable, and my other monitor in mirrored mode. Today the issue re-occurred, with the VGA monitor fine. Switch the HDMI monitor off and back on the and it is fine, not ideal, but a work around.

 

[Jimmysb]

Change of cable did not improve matters, I have a HDMI/DVI adapter, and my current VGA monitor will take DVI, so I will give that a go and see what happens.

 

[Jimmysb]

Here is a troubleshooting procedure that might help:
Mac Wake Up Screen Glitch - Apple Community

That is a very old discussion and some of the steps don't apply to the new Mx systems, particularly the way to do a Safe Boot and to do disk repairs. But the rest is still useful as a guide to troubleshooting.

I looked at the page, however as this is a new Mac Mini, with the first occurrence just a couple of days after buying it with no peripherals except monitors connected, and no software added, then a number of the solutions don't apply, and I am running Ventura.
To be more specific about the issue: The screen goes to "static" for a few seconds, then turns black (as when it is about to go to sleep), then back to "static", then black again, it does this a couple of times, then we are up and running again, a separate monitor on VGA mirroring is fine, during this. The issue is random, it is normally after the monitor has gone to sleep (and system (I think)), after the first couple of times, an internet search talked about "energy saving", and after the changes to sleep mode it was almost a week till it happened again. Next was a cable change, and a 3-4 day gap before occurring again. The article talks about reboot, but switching the monitor off and on works, though it could be re-setting itself anyhow.
Due to the randomness it is difficult to reproduce, so taking the Mac back to the shop would be a waste of time, as the issue probably would not happen.
I have a HDMI to DVI convertor on the way, and this will connect to my VGA monitor, and I will connect my HDMI monitor via VGA, and see which monitor is affected, this should help give some direction.

 

[MacInWin]

I looked at the page, however as this is a new Mac Mini, with the first occurrence just a couple of days after buying it with no peripherals except monitors connected, and no software added, then a number of the solutions don't apply, and I am running Ventura.
To be more specific about the issue: The screen goes to "static" for a few seconds, then turns black (as when it is about to go to sleep), then back to "static", then black again, it does this a couple of times, then we are up and running again, a separate monitor on VGA mirroring is fine, during this. The issue is random, it is normally after the monitor has gone to sleep (and system (I think)), after the first couple of times, an internet search talked about "energy saving", and after the changes to sleep mode it was almost a week till it happened again. Next was a cable change, and a 3-4 day gap before occurring again. The article talks about reboot, but switching the monitor off and on works, though it could be re-setting itself anyhow.
Due to the randomness it is difficult to reproduce, so taking the Mac back to the shop would be a waste of time, as the issue probably would not happen.
I have a HDMI to DVI convertor on the way, and this will connect to my VGA monitor, and I will connect my HDMI monitor via VGA, and see which monitor is affected, this should help give some direction.

The user manual for the HP 202 monitor says this:

1. The monitors support a reduced power state. The reduced power state will be entered into if the monitor detects the absence of either the horizontal sync signal or the vertical sync signal. Upon detecting the absence of these signals, the monitor screen is blanked, the backlight is turned off, and the power light is turned amber. When the monitor is in the reduced power state, the monitor will utilize 0.5 watts of power. There is a brief warm-up period before the monitor will return to its normal operating mode.

So, when the Mac goes to sleep, there are no signals to the monitor. Then when the Mac wakes up, it sends out signals to the monitor and the monitor detects that there is a signal. At that point, the monitor searches for inputs. Page 11 of the manual says:

The monitor automatically scans the signal inputs for an active input and uses that input for the screen.

I suspect the flashing you see is the monitor searching the ports for an active inputs and adjusting to the signal coming in. You can try disabling the power saving function of the monitor, if the monitor allow it, to see if that helps.

 

[Jimmysb]

The user manual for the HP 202 monitor says this:


So, when the Mac goes to sleep, there are no signals to the monitor. Then when the Mac wakes up, it sends out signals to the monitor and the monitor detects that there is a signal. At that point, the monitor searches for inputs. Page 11 of the manual says:


I suspect the flashing you see is the monitor searching the ports for an active inputs and adjusting to the signal coming in. You can try disabling the power saving function of the monitor, if the monitor allow it, to see if that helps.

Jake, many thanks, however I have been using this monitor on both my home PC (windows) and my works laptop since buying it in 2021, and I have never had this problem, though I do believe it is something to do with power saving.

 

[nickyr]

I had problems running my monitor via HDMI. I gave up in the end and just use the TB port instead.
Not very helpful I know, but just thought I'd chime in

 

[Jimmysb]

I had problems running my monitor via HDMI. I gave up in the end and just use the TB port instead.
Not very helpful I know, but just thought I'd chime in

I may go a similar route, as mentioned the monitor with HDMI never gave problems previously, so I can only assume it is something in the Mac output it does not like!

 

[Jimmysb]

Just to recap: I have a HP E202 connected via HDMI, and a HP x20LED connected via VGA, and it is just the E202 (HDMI) that has the issue.
Current situation: I have a HDMI/DVI-D convertor, so the HP E202 will be connected via VGA, and the HP x20LED will be connected to the DVI-D through the HDMI convertor.
Outcome: If the problem arises via the HP E202, then this would be a monitor issue, if the problem arises through the HP x20LED then this would be a HDMI issue, however is the problem does not occur again I would assume the it is the HDMI / HP E202 incompatibility issue.
I will keep you all informed.

 

[Jimmysb]

This afternoon the issue occurred again, only this time on the HP x20LED, HDMI output through a converter to DVI-D, so the only constant is the HDMI output, so this is where the issue arises from.
What next!!

 

[MacInWin]

I didn't read the entire thread, but have you changed the HDMI cable? Not all HDMI cables are the same and quality is key for the cable.

 

[Jimmysb]

I didn't read the entire thread, but have you changed the HDMI cable? Not all HDMI cables are the same and quality is key for the cable.

Two different cables, and a DVI-D cable.

 

[Jimmysb]

So some months later, with the HDMI output via a HDMI - DVI-D adaptor to my second monitor, I have decided Apple support is the next stage before the Warranty runs out. So main monitor direct to HDMI, second monitor VGA via Apple adaptor to thunderbolt, with the exception of my Seagate Drive for TM everything else disconnected. I need to monitor when the screen goes "static", and what sorts it out, however currently no issues, so maybe it was software, and has been fixed.

 

[Jimmysb]

Quick update, my Mac has be "on" for almost 24 hours with the HDMI output connected directly to my main monitor, and has been through the various cycles, of stand-by and sleep, and as yet no monitor issues. My early assumption was that is was a driver issue, if it was (and I will never know) it seems to be fixed, though, I would be content until it has been running for a week or more without issue.

 

[Slydude]

I'm glad things are working for you now.

This might be a driver/software issue but my bet is on an intermittent adapter/cable failure. I had this issue with an adapter running from the Thunderbolt port on my iMac to an HDMI-equipped monitor. The setup would work for days at a time with the very kind of failure you're experiencing.

I thought I had posted this previously.

 

[Jimmysb]

I'm glad things are working for you now.

This might be a driver/software issue but my bet is on an intermittent adapter/cable failure. I had this issue with an adapter running from the Thunderbolt port on my iMac to an HDMI-equipped monitor. The setup would work for days at a time with the very kind of failure you're experiencing.

I thought I had posted this previously.

I have a number of HDMI cables, and the problem was with each one, which is why I dismissed the cable as being the issue.

 

[Jimmysb]

The issue just reappeared, been out all day, wake the computor by left click on the mouse, and "static" screen, power off the monitor and back on, no issue. Though, a thought, I do normally power off the monitor at night, so switched on in the morning.

 

[Jimmysb]

I have been changing my settings in relations to external drive not ejected properly, and the issue has now started again:

My setting are:







For this, I am running two monitors, HP E202 on HDMI, and HP x20LED on VGA via an Apple adaptor, the 20 LED is mirroring the E202.

After 3 minutes both screen show the screen saver, and after 5 minutes both screen go to standby. Now this is where the issue starts, after about 10 minutes the E202 comes out of stand by, with the x20 staying in stand-by. The E202 screen changes intermittently from blank to this, as you can see the other screen in stand-by (orange power LED):




When I awaken the screens (move the mouse), the x20 comes on but the E202 remains with this screen. Switching the E202 off and on restores normal service.

 

[Jimmysb]

Having changed the setting in the first screenshot:



I left the system for an hour, the screen went off as usual, remained off, and when awoke, the screens came on as normal.