An issue with M1 Max MacBook and video projectors

[Notawiz]

I recently purchased a brand new MacBook M1 Max. After several attempts, I finally found a way to get my three external displays working. My main display, a 4K Dell, is connected via HDMI (directly from MacBook's HDMI port). The two side displays, identical HD monitors by LG, are also connected via HDMI from a Thunderbolt hub.

The setup has worked pretty much flawlessly for several weeks — only occasionally the side displays switched places, but that stopped when I turned off the sleep mode automation in the Settings. So yes, at the moment my MacBook is always on and awake. Not sure how healthy that is to the computer. The lid is closed — at home I only use the external displays, Bluetooth keyboard and mouse.

Yesterday, however, I unplugged all external devices and took the laptop with me. We are preparing a big show, and I'm planning to use this computer for video projection.

So, I tried to connect my laptop to two different video projectors, one Panasonic and one Mitsubishi. Panasonic was a bit older and I had to use HDMI to DVI-D adapter cable. Mitsubishi, not particularly new either, had an HDMI port, so a normal HDMI cable was sufficient. To clarify: I tried them separately, not at the same time.

Both devices projected the image just fine. But I had a similar issue with both of them:

After a minute or so, MacBook turned on the sleep mode. And when doing that, it also somehow messed up the usage of both projectors. If I kept on doing something on my MacBook (moving the cursor or anything), it didn't turn on the sleep mode.

As I already mentioned, the sleep mode automation in the Settings is set to "Never".

For the life of me, I can't figure this out. Is there a known issue with M1-series MacBook and HDMI? I don't think so, since my three displays at home work just fine. Also, I didn't find anything by googling.

So, two different projectors, two different cables. Both doing the same thing. My MacBook is the common nominator.

Could this have something to do with different generation HDMI? I assume that even the newer projector (the one with the HDMI port), uses an earlier version of HDMI.

Mac OS is up-to-date, Monterey 12.5.1.

Any ideas?

 

[appltech]

And what if you try to move "Turn display off" slider ( –> System Preferences –> Battery –> power adapter or battery, depends on usage) to "Never"?
With "Prevent your Mac from sleeping automatically", and that slider, your Mac should be always on duty

 

[macsound1]

Are you still using the thunderbolt dock to make the 2nd HDMI port?

 

[altaic]

I assume you were connected to power at home. Were you connected to power when using the projectors? If not, it seems like @appltech has it right— you need to specifically disable automatic sleep when on battery power.

 

[Notawiz]

Ooohh right! Thank you! It's my first laptop in fifteen years, I just didn't realize that there are two sliders — one for usage when connected to power and one when you're only on the battery! I had moved the slider to "Never" in Power Adapter tab, but not in the Battery tab!

I'm relieved to find out it was just something simple that poor silly old me didn't notice. Phew! 😆

Next time I'll move both sliders to "Never" AND I'll connect my MacBook to the wall.

As for macsound1's question, I tested the projectors one by one, so I did that using MacBook's own HDMI port. But the goal is to be able to use two projectors simultaneously. I guess it's possible that I won't be able to do that just on battery — so I will definitely connect both the computer and the Thunderbolt hub to power.

Thank you very much! I have to start remembering that I'm a laptop guy now. 😂