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LG UltraFine 5K - Issues/bugs

Hey guys, hoping someone can help me out. I sent my dad my LG Ultrafine 5K, and he's having a few issues. Here is what's going on:

  • The LG 5K Display is being registered as connected to the laptop, and showing up Displays under System Preferences.
  • LG Ultrafine 5K is not turning on (screen remains black, and nothing shows up)
  • He's receiving the following message: "CANNOT USE THUNDERBOLT ACCESSORY. Connect accessory using a thunderbolt capable cable" (yes, that is how it is written out)
I tried having him unplug/re-replug everything, and opening/closing the laptop lid. I'm 99% sure he purchased the correct cable, but I guess I should verify that with you guys too. He recently upgraded to Big Sur, so unsure if there are any compatibility issues with that.

Any help is appreciated!
 
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He just confirmed that it does have the lightning bolt printed on the connectors. The LG Monitor is definitely visible when I look in System Preferences.
 
Here are some photos & video for reference - i did this to verify everything looked ok, but maybe you guys can find something that I didn't.




IMG_4314.jpg
 
It may be a bad cable or even a bad port? I just tried a regular USB-C cable (came with Mac as charging cable) and got
Screen Shot 2020-11-25 at 2.19.05 PM.png
 
The cable that comes with the LG is black. Shouldn't make a difference if real TB3 but who knows.
 
strangeengine said:
My original 5K cable has failed. I had to replace it with an eye-wateringly expensive Apple TB3 Pro cable ($129!!).
Click to expand...
That's not expensive. Try one of the new optical TB3 cables from Corning; only ~$400!

BTW, most $50 2m active TB3 cables work too, so unlucky.
 
jimthing said:
That's not expensive. Try one of the new optical TB3 cables from Corning; only ~$400!

BTW, most $50 2m active TB3 cables work too, so unlucky.
Click to expand...

All the cheaper 2m cables I could find on Amazon were limited to 20GB/s and this monitor seems to be very sensitive to cables, so I didn't want to take the chance.
 
strangeengine said:
All the cheaper 2m cables I could find on Amazon were limited to 20GB/s and this monitor seems to be very sensitive to cables, so I didn't want to take the chance.
Click to expand...
Those 2m ones at 20Gb are passive ones. The ones rated at 40Gb are active, with most doing the 100W power, too. 😉
 
Just as a follow up - tried a new cable, and still not working. I'm beginning to think something happened during shipping that is causing this : (

Has anyone ever tried repairing one of these out of warranty?
 
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thomasec said:
Just as a follow up - tried a new cable, and still not working. I'm beginning to think something happened during shipping that is causing this : (

Has anyone ever tried repairing one of these out of warranty?
Click to expand...

Yes, I have - about 2 months ago. I found a local repair center on LG's list of authorized repair centers. It was $450 to replace the main board.

If you are in the SF Bay Area (South Bay), I used:

www.yelp.com

Parts4Pros - Campbell, CA

Specialties: We do Offer TV repair. TV Repair, Parts & Sale Same Day Service / We offer In-Home TV Repair Our Technicians have more than 15 years of experience serving San Jose and cities around. We do offer TV sells and installation. Established in 2009. Parts4Pros TV Repair has been...
www.yelp.com www.yelp.com

BTW, they said that repairs on these monitors are very, very common.
 
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strangeengine said:
Yes, I have - about 2 months ago. I found a local repair center on LG's list of authorized repair centers. It was $450 to replace the main board.

If you are in the SF Bay Area (South Bay), I used:

www.yelp.com

Parts4Pros - Campbell, CA

Specialties: We do Offer TV repair. TV Repair, Parts & Sale Same Day Service / We offer In-Home TV Repair Our Technicians have more than 15 years of experience serving San Jose and cities around. We do offer TV sells and installation. Established in 2009. Parts4Pros TV Repair has been...
www.yelp.com www.yelp.com

BTW, they said that repairs on these monitors are very, very common.
Click to expand...

Appreciate all of that! If anyone knows of any repair centers in the DC/VA/MD metro area, let me know!
 
Hey guys,

I'm using dual LG Ultrafine 5K since 2+ years with my 2017 15" MBP. Last year my #1 port of left side is stopped to work with both of displays. Yesterday right sided display started continuous blinking (was happened before but it was temporary) and I tried to plug it second port of right side. Later, I lost connection with both monitors, blank dark screen. After hundreds of restarts and resetting NVRAM, PRAM, the monitor on the right and sometimes on the left worked, but there was never an image on either of them.

Currently, when I connect two or one LG Ultrafine to MBP, the MBP does not boot on with the power key. It instantly turns on/boot when I pull out the monitor cable(s) connected.

When I connect the cable(s) belonging to the monitors when it comes to the login screen, the MBP freeze and I cannot do anything. The Macbook has a login display on its own screen, but the keyboard and trackpad are not working. Of course, there is no image on the monitors during this time. Black screen.

Do you think the problem is with the monitors, MBP or the cables? I see low chances of being on cables and monitors because how can both be broken at the same time and nothing can work now? When monitors are connected, how can they make the MBP freeze instantly?


Also heres weird Link Status and Speed from left sided monitor/port. Meanwhile, the monitor on the right is working, but the screen turns black and comes back every 1 minute and left is completely not working (black screen).

Left sided port shows that speed is 20gb/s and link status 0x2 / 0x1

Left side:
CleanShot 2020-12-13 at 11.22.33@2x.png



Right side:
CleanShot 2020-12-13 at 11.46.45@2x.png


Thanks.
 
saulinpa said:
@merdinger: could also be a bad cable adding to the mess. Is there any way you can borrow another MBP to test with?
Click to expand...
I tried 10+ more NVRAM and SMC reset and can successfully run monitors on right thunderbolt ports. But left ports are pretty broken. When I connect them into left ports they are charging MBP but never turning on display. So probably second port also broken like first one in last year.

Yes, I have two cable due to dual monitors so one is working perfect with both monitors. Other one is not working on right side too. So, one is absolutely corrupted. When I connect this "bad" cable into right ports sometimes System Report shows that connected LG Ultrafine but with speed 20Gb/s but never turning on both displays.

I got an appointment with premium apple service for tomorrow. First I need to solve broken left side ports to understand if there is any damage with monitors. Also I ordered a new thunderbolt 3 cable (0.8m) from Apple Store right now.

In my country, by the law LG can't refuse my repair requests at least for 5 years after I bought it. And If they don't have equipment/parts to repair it they have to give me similar 5K monitor or money refund within this 5 years. So I hope it is not MBP problem. If it is I need to repair my ports every 1-2 years. I believe MBPs can't handle that much power (both charging and delivering 5k) from dual 5K and thats why most of people can't turning on their monitors with similar setup by time.
 
It sounds like you have too many problems for anything to work. Yes, get the MB fixed as you know there are identifiable problems. Good that you are getting a cable from Apple as some cables have had issues. Only then can you start looking at the displays. Good luck on any repairs as from posts here LG isn't helpful.

There are millions out there but from my experience the USB-C ports are too fragile. I had a MBAir that I returned after one of the ports became loose in less that a week.
 
merdinger said:
I tried 10+ more NVRAM and SMC reset and can successfully run monitors on right thunderbolt ports. But left ports are pretty broken. When I connect them into left ports they are charging MBP but never turning on display. So probably second port also broken like first one in last year.

Yes, I have two cable due to dual monitors so one is working perfect with both monitors. Other one is not working on right side too. So, one is absolutely corrupted. When I connect this "bad" cable into right ports sometimes System Report shows that connected LG Ultrafine but with speed 20Gb/s but never turning on both displays.

I got an appointment with premium apple service for tomorrow. First I need to solve broken left side ports to understand if there is any damage with monitors. Also I ordered a new thunderbolt 3 cable (0.8m) from Apple Store right now.

In my country, by the law LG can't refuse my repair requests at least for 5 years after I bought it. And If they don't have equipment/parts to repair it they have to give me similar 5K monitor or money refund within this 5 years. So I hope it is not MBP problem. If it is I need to repair my ports every 1-2 years. I believe MBPs can't handle that much power (both charging and delivering 5k) from dual 5K and thats why most of people can't turning on their monitors with similar setup by time.
Click to expand...
Incidentally, what country are you in? It helps others in future.

As for issues, it looks like you have one bad cable, and maybe bad ports on the MBP. Swap the bad cable for a known good one first to see if that's the underlying issue, so you know that with two working cables+screens the problem is resolved or not (i.e. the bad one maybe causing all the issues you're having). If not fixed, then investigate getting the MBP ports fixed, then the LG.

FWIW, I've had a maxed-out 2016 MBP15 running two 5K's without problems, so they can handle it. And newer versions improve on that.

Anyway, do come back and tell us how your Apple &/or LG fix experiences got on. That'll be interesting to know for sure. :)
 
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Bug fix just for us in MacOS 11.1: States that it fixes a problem with M1 Macs that display 4K instead of 5K on the LG UltraFine.
 
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Hey, I'm living in Turkey.

After about 2 weeks of adventure, I solved my problem. With 2x 0.8m thunderbolt 3 cables I bought from Apple ($110 it is expensive than any other country in the world due to high taxes on Turkey), I was able to run one of the monitor on any port without any problem, but even if my other monitor (broken one) displayed an image, it was constantly blinking. LG service replaced the motherboard of this monitor for $220 (it is including service fee too) and now I can use both monitors without any problems.

So although I used LG's problematic monitors with great care, it cost about $330 after 2.5 years, and it was just because one monitor was causing trouble. I hope the other monitor has a longer life. It's pretty sad that this monitor doesn't have any alternative.
 
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The official Apple Thunderbolt cable ($39/USA) fixed my resolution issues with the LG 5K.

Thunderbolt 3 USB‑C Cable 0.8 m - Apple

Apple Store Search Results
www.apple.com

There were some random blanking issues which were solved by 11.2 Beta. Though I don't recommmend installing the beta just yet as it has it's own instabilities and you won't be able to (easily) return back to 11.1.
 
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I have my MBP connected to the display and have auto brightness enabled. Is the auto brightness als supposed to work on the LG display (based on the brightness sensor in the MBP)? I think I once read something about this in the past but I could be wrong. In my experience it doesn't seem to work.
 
chris4565 said:
I have my MBP connected to the display and have auto brightness enabled. Is the auto brightness als supposed to work on the LG display (based on the brightness sensor in the MBP)? I think I once read something about this in the past but I could be wrong. In my experience it doesn't seem to work.
Click to expand...
Not supported (or maybe only available on recent revisions of the LG display). For older LG displays, there is a sensor but it doesn't "talk" with macOS.
Only way to make it work is via a 3rd party app (I use it, works fine): https://github.com/OCJvanDijk/Brightness-Sync
 
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