Trouble connecting 2018 MBP and 4K LG UltraFine (22-inch)

[mattbc]

Hey all, I purchased a used LG UltraFine 4K 22-inch monitor but am having issues connecting it with my 2018 Macbook Pro. The previous owner plugged in his MacBook to show me and it worked perfectly, but when I plugged it into mine when I got home, the MBP screen goes black and nothing happens to the display. I’m worried somehow the display got damaged in transit, but the MacBook seems to recognize a display is connected. Wondering if anyone here has heard of similar issues or has any ideas to help troubleshoot.

Things I have tried so far:
- restarted my macbook
- checked if the power and usb-c cables are in the correct ports
- tried to verify if there was something wrong with the cable. I used the included USB-C cable with a charger and my iPad Pro and it was able to charge the iPad
- tried to verify if the monitor is working. Don’t know, but it does seem to carry a charge. I can’t tell if it’s powering my MacBook when I plug it in since the screen is black, but it makes the “connected” sound on my Mac. Separately, I tried using a USB-C charging cable plugged into the monitor, and it produces a charge.
- tried adjusting brightness but couldn’t — the touch bar freezes when the display is connected. Funny thing: the brightness shows up after I disconnect... it executes whatever I tapped while the display was connected, but only after I unplug the monitor.

Haven’t yet had a chance to try and connect it with another thunderbolt 3 MacBook Pro. Separately, has anyone had to send in their monitors to LG? They had told me it would cost $150 and about a week to service.

Thanks!

 

[lessejv]

hi dear friend, I am also having the same problem, I also bought an apple thunderbolt 3 cable to see if the problem is the cable and it is not, I also tested a android smartphone with USB-C which used to mirror the screen to the display and it keeps black, what I know is the display charges the macbook and any accessories and it also plays the accessories sound, but when connected with the macbook everything goes black and macbook freezes.

 

[NJRonbo]

Driving these large monitors has been an ongoing issue with the MacBook Pro.

You need one of the more powerful models, particularly with the Radeon graphics.

The 13" models do not have these.

 

[lessejv]

ok this can be a mbp recurrent problem, but I don't think it have any relation to our LG Ultrafine problem since my macbook works just fine with other 4K tvs and displays, on the other hand the LG Ultrafine does not work with anything.

 

[NJRonbo]

I have to take back my previous comments and I apologize.

A 22" monitor should have no issues with a MBP.

I thought the user had a much larger monitor.