LG External Display Screen Turns Black Randomly (38WN95C-W.AUS)

Looks like nobody else is weighing in here so I thought I'd post a quick update for anyone else who comes across this post. Apple released macOS Monterey 12.3 a few days ago and I upgraded right away. I don't want to jinx it, but (so far) I haven't encountered the random black screen issue at all since I installed that update. It's only been about 6 days though, so I'm not holding my breath yet. I looked through the 12.3 release notes here:

What's new in the updates for macOS Monterey - Apple Support

There is nothing listed about bug fixes for 3rd party monitors, but Universal Control is a new feature that is focused around displays right? Maybe that was a factor? I'll keep my eye on it.

If anyone has any insights, please post them here.

Hi Bob32,

Don't misunderstand. The black screen issue existed BEFORE the 12.3 update that enabled Universal Control. I was just speculating over the fact that Apple did something under the hood to add Universal Control in 12.3 and since that was a video related update, maybe whether they did fixed my issues as well. I just don't see anything in the release notes about bug fixes for 3rd party monitors, but I (literally) have not had the random black screen issue since that update. I don't know what changed, but something they did fixed it.

I guess my issue is resolved!

So dropping the refresh rate to 60 Hz seems to have helped a little. I only had two incidents of the black screen occur so far. Swapping the ports now to see if that makes a difference.

Hey Grant,

Yeah, pretty sure the cable wasn't the issue. All I have connected to the MacBook is a single Thunderbolt cable going to the monitor on a port on the left side and a USB-C to Ethernet adapter on the right. So I doubt that is the issue. In my head I keep coming back to the fact that this monitor supports 144 Hz refresh rate. Apple just dropped their new 27" Studio Display this week and it is capped at 60 Hz. If only I had known that was coming, I would have just waited for it instead of buying this!

Anyway, thinking back over all the troubleshooting I did this past month, I honestly can't remember if I tried backing the display down to 60 Hz in the macOS Display settings. So I'm trying that now to see if it makes a difference. The monitor seems to work just fine when I connect a Windows laptop to it, so I don't think its defective, but if that's the case then I cannot be the only person having this problem right? That's why I posed my question here.

Any other ideas (from you Grant) or anyone else?

That's what I'm telling you Grant, I don't have a power adapter connected. This monitor supplies the correct amount of power over its Thunderbolt connection to both charge and connect the Macbook to the display over a single cable. See the specs here:

https://www.lg.com/us/monitors/lg-38wn95c-w-ultrawide-monitor

This capability was the main reason why I chose to purchase this display to replace the LG 5K UltraFine I purchased direct from Apple several years ago. Just one cable to run to my MacBook. Your idea is a good one, but (in my case) there is no power adapter to take out ot the mix.

Any other ideas?

Hi Grant,

See my answers below.

- Mac Model Name: 16-INCH MACBOOK PRO (SPACE GRAY, LATE 2016), Model Number: A1707 (Intel-Based)

- Graphics: AMD Radeon Pro 5500M 8 GB

- Version: macOS Monterey v12.1.

- Thunderbolt Cable: I have tried three, the one that came with the monitor, a brand new Apple-branded Thunderbolt cable and a generic 3rd party Thunderbolt cable. All produced the same results. I am currently using the Apple-branded Thunderbolt cable linked below as it seems to be the most stable of the three:

https://www.apple.com/shop/product/MQ4H2AM/A/thunderbolt-3-usb%E2%80%91c-cable-08-m

Let me know your thoughts!

Fair point Grant, I'll try that!