Display goes dark.

[gavspen]

Hi All,

New odd behavior. I've got two displays. Lately, one of them, always the same one, will go dark for a few seconds if the mouse is moved after it hasnt been moved for a little while, say 3-5 mins.

I do have a spare display and I will swap it out at some point, which will tell me if it's the mac or the display, but I though I'd ask anyway. Any ideas?

Gavin

[Phil O]

I notice you have an M1 mac mini. Is that display connected via HDMI port by any chance?

Your friendly neighborhood Phil

[gavspen]

I notice you have an M1 mac mini. Is that display connected via HDMI port by any chance?

Your friendly neighborhood Phil

No Phil, it's in one of the Thunderbolt ports (is that what they're called?) Either way, it's in the same port it always was. This is new weirdness.

[mikehalloran]

Since this is repeatable behavior, I'd get Apple involved. They can install a diagnostic bot on your system to observe this and capture system data if necessary.

In the meantime, have your System Settings/Displays or System Preferences/Displays window (depends if Ventura or an older OS) visible on the screen that doesn't go dark and see what happens there. Apple will be looking at that, too.

Another thing to try is having the Activity Monitor up. Look for any activity turning red as this happens. If so, drill down on it immediately and that should reveal anything causing a conflict.

[mothra]

An Apple Tech is more than likely going to blame the monitor, they don't really like to admit when their precious little toys have issues. See this issue all the time with M1/M2 models and our monitors at work, and have had several customers actually need to have Apple replace their Mac's for it (when the M1's first came out there were A LOT of GPU issues with them). We seem to have lucked out and got a good pair of MacBooks as I can go check out any of our products from the warehouse and they work fine when I test them. Some customers with the exact same setups, nothing but headaches.

Does the monitor have an HDMI input on it? Get a DVD player or something like a Roku/Fire Stick and plug it in and let it run for awhile. If the monitor has no issues blacking out and disconnecting, it's either the Mac or the TB cable. Could be the TB port on the monitor, but I'd bet its the Mac and its 'quirks'. At least you're not seeing the ghosting or screen tearing a lot of the first gen M1's were. The new gen Mac's are just REALLY picky when it comes to displays it seems.

[gavspen]

I agree, Mothra, that Apple would likely say "it's got to be the monitor, our stuff never fails", haha.

No HDMI. It's an ancient VGA monitor (Samsung Syncmaster) connected with adapters/converter cables, etc. But it's weird that this just started happening, isnt it? I could see some kind of incompatibility, sure....I mean, it's OLD!.....but to be fine for months and then start acting up? I dont get it.

I'll try what you suggest Mike and see if it shows anything, but what might I see in System Preferences/Displays? That's just for settings, isnt it? I dont see any diagnostic type stuff there.

[mikehalloran]

…I mean, it's OLD!.....but to be fine for months and then start acting up? I don't get it.

It certainly can be the monitor/cable/adapter. Heat is your enemy and old components may start acting up if left dormant for a long time.

I prefer to know. If guessing can be eliminated, I'm for that.

I'll try what you suggest Mike and see if it shows anything, but what might I see in System Preferences/Displays? That's just for settings, isnt it? I dont see any diagnostic type stuff there.

You are looking to see if the MacOS still shows the monitor visible in Displays before or after it goes dark. If it disappears before the monitor goes dark, that's different than if the monitor goes dark first. If it stays visible in Displays, that's another issue entirely. Is the Mac shutting down the monitor or is the monitor telling the Mac that the connection has broken?

That this happens with a mouse movement is suspect. Apple can do a data capture that can be sent to Engineering. If it is Mac hardware acting up, they will know.

Same with the Activity Monitor. If something turns red, double-click on it immediately. There will be a new screen with two tabs. Open both and keep on drilling down till there's nothing left to open. What do you see? If it's a 3rd party .kxt or daemon at the end of that tunnel, that's the likely culprit. If it's an Apple process that pops up when the monitor crashes, back to faulty hardware.

With the energy savings that new, backlit LCD monitors enjoy, replacing that VGA will pay for itself sooner than you think. You do not need to use the TB port or a TB cable unless 5/6/8K. If the HDMI port is in use, an inexpensive USB-C to HDMI or DVI cable is fine for current 2K or 4K displays.

[gavspen]

Thanks for all that Mike. I will attempt to digest and give it a shot.

[gavspen]

By the way Mike, both my USC ports are in use so Thunderbolt is all I've got left.

Also, no it's not just doing it doing after being idle for a while, it's just random, but always just for a second or two. For now, that is; something seems to be going from bad to worse. Oy.

[mikehalloran]

Your USB-C ports are TB only when they need to be. Otherwise, USB-C is a port, not a protocol. Yours supports a laundry list of of compatibility including HDMI and DVI — all you need are the right cables.

Only 5/6/8K monitors require TB3 cables. 4K and below AV cables are far less expensive. Check the specs before buying. The USB-C to DVI cables connecting my 27” 4K LGs cost me $9 each a few years ago.

[James Steele]

I have had one of my monitors, a fairly new LG 32" monitor give me some instability and some flashes. It's connected to a TB3 port via a TB3 to HDMI adapter. It would sometimes happen when I would boot my Mac Studio from the Recovery volume, but would go away when I booted normally. It once gave me a good scare by periodically flashing black now and again.

In my case, it went away and didn't come back by me unplugging and re-plugging the TB to HDMI adapter from the Mac Studio while the Mac Studio was running. Having the OS sort of "re-aquire" the monitor, settled it down and I've had no problems since. You may have tried it already, but if not, while your Mac is running, unplug and replug the cable going to the monitor from your Mac.

Apologies if this doesn't help. Just throwing it out there.

[gavspen]

Your USB-C ports are TB only when they need to be. Otherwise, USB-C is a port, not a protocol. Yours supports a laundry list of of compatibility including HDMI and DVI — all you need are the right cables.

Only 5/6/8K monitors require TB3 cables. 4K and below AV cables are far less expensive. Check the specs before buying. The USB-C to DVI cables connecting my 27” 4K LGs cost me $9 each a few years ago.

Yeah, I confess the whole USB-C/TB thing was confusing me. It's just a shape, basically. Haha.

The weirdness is much less predictable that it was at first. Maybe I'll start hunting for a new monitor. Sigh.......

[gavspen]

You may have tried it already, but if not, while your Mac is running, unplug and replug the cable going to the monitor from your Mac.

Apologies if this doesn't help. Just throwing it out there.

James, you have nothing to apologize for around here. Ever.

I actually did that and it settled down for a while, but now it's back, but much less frequently. There's one other link in the chain that I didnt unplug/plug (I gotta lotta cable here!) so I'll do that one too. Just like the old analogue days, eh?; reseat the cable and hope the problem goes away.

[gavspen]

In case you're wondering......and I'm sure you've all been on pins and needles. Haha......this odd behavior has disappeared just as mysteriously as it appeared. No changes of any kind that I'm aware of. What strange things computers are.

I'll sure it'll be back at some point, but for now........¯\_(ツ)_/¯