Macbook Pro 2017 - USB-C Monitor not working

Discussion in 'MacBook Pro' started by NielsO, Aug 8, 2017.

  1. NielsO macrumors newbie

    NielsO

    Joined:
    Jul 28, 2017
    #1
    Hi Guys,

    My Macbook Pro from 2017 does not recognize the new LG 43UD79-B. I connected the display with a new Caldigit Thunderbolt 3 cable. My macbook does recognize that there is a display connected some how. But in system information I can only see that my MB is powered with only 7 watts.... Normally the display would power 60watts.

    I can't find the solution and it would be great if you guys could help me out.

    I will add a couple of screen shots so you can see what my MB does.

    Schermafbeelding 2017-08-08 om 12.32.02.png Schermafbeelding 2017-08-08 om 12.33.01.png Schermafbeelding 2017-08-08 om 12.34.09.png

    Thanks!
     
  2. JohnnyGo macrumors 6502a

    Joined:
    Sep 9, 2009
    #2
    It seems to me that the issue is with your Thunderbolt dock. Most docks do not charge at 60-87 watts (MBP 13-15”) but rather at 30-45 watts.

    But your info regarding charging with 6-7 watts may be a “net charge”, meaning the TB3 dock my be charging at 15-30watts and your Macbook is using 10-20watts.
     
  3. Brookzy macrumors 601

    Brookzy

    Joined:
    May 30, 2010
    Location:
    UK
    #3
    It’s probably the cable.

    Thunderbolt 3 cables longer than 0.5 metres do not have full USB compatibility.

    Try the cable that came with the display or another 5 or 10 Gbps USB-C cable (not the 480 Mbps charging cable that came with your MacBook).
     
  4. NielsO thread starter macrumors newbie

    NielsO

    Joined:
    Jul 28, 2017
    #4
    Could it be that the cable must support USB 3.1/3.0 backwards compatibility? Could this solve the problem?
    I am willing to send the cable back and buy a new one. But if I would buy a new one I have to be sure that it will work.
     
  5. brazosdog02 macrumors newbie

    Joined:
    Sep 17, 2014
    #5
    ANy luck with this? I have the same monitor and Macbook Pro. When I plug the macbook into the monitor using the proper USBC to USBC cable, no display is shown or recognized by either macbook or monitor.

    I don't want to use adapters or HDMI. I want to use USBC, but apparantly, this function is not available, which seems kinda goofy.
     
  6. Samuelsan2001 macrumors 604

    Joined:
    Oct 24, 2013
    #6
    USB c to USB c will not work your screen has a usb c for peripherals and hard drives etc, not video input you need a usb c to display port cable. Something like this

    https://www.amazon.co.uk/dp/B01LYD2Y19?gclid=EAIaIQobChMIrZydsILz2AIVBYuyCh0-OwQcEAAYASAAEgLkmPD_BwE
     
  7. planetf1 macrumors 6502

    planetf1

    Joined:
    Aug 8, 2014
    Location:
    Hampshire, UK
    #7
    I have a MBP 2016 15 TB. The LG 27UD88 works fine over USB-C for 4K display output & power, plus the downstream USB devices connected to monitor work at USB-2 speeds. I used the cable LG supplied with the monitor. Did LG supply one with this monitor? Does sound odd it doesn't work. USB-C is connected directly not via hub?
     
  8. brazosdog02 macrumors newbie

    Joined:
    Sep 17, 2014
    #8
    It works, but the only way it works is if you plug everything in and then unplug and replug the usbc at the monitor. Otherwise, it won't sense the signal.
     
  9. andy9l macrumors 68000

    Joined:
    Aug 31, 2009
    Location:
    England, UK
    #9
    If he has the 43UD79, it should accept USB-C for 4K video, data and 60W charging.

    This sounds stupid, but try swapping ends of the LG USB-C cable - i.e. put the end currently in your Mac into the monitor, and vice versa.

    I also have a 27UD88 and when doing my research I remember reading that a number of people found this to fix a number of issues they had with Macs. It doesn't make any sense, I know - but try it.
     
  10. brazosdog02 macrumors newbie

    Joined:
    Sep 17, 2014
    #10

    That DOES sound stupid, but I've fixed issues with dumber ideas. I'll give it a go!
     
  11. NielsO thread starter macrumors newbie

    NielsO

    Joined:
    Jul 28, 2017
    #11
  12. brazosdog02 macrumors newbie

    Joined:
    Sep 17, 2014
    #12
    You nailed it. This cable does work, but only one way. That can't be normal. Found another cable that works both ways. So wierd.
     
  13. andy9l macrumors 68000

    Joined:
    Aug 31, 2009
    Location:
    England, UK
    #13
    Haha, brilliant! Can't believe that's a thing.
     
  14. brazosdog02 macrumors newbie

    Joined:
    Sep 17, 2014
    #14
    It makes no scientific sense to me. Its a ***** wire. How does it's direction matter?!
    Im being told by manufacturers that if the cables are being that fickle that the port on my devices is faulty. Thoughts? Is that possible if I find cables that work fine?
     
  15. andy9l macrumors 68000

    Joined:
    Aug 31, 2009
    Location:
    England, UK
    #15
    I doubt it’s the ports. Cheap/dodgy cable manufacturers more likely to be at fault. There’s all sorts of issues with USB-C and Thunderbolt cables and docks at the moment.
     
  16. brazosdog02 macrumors newbie

    Joined:
    Sep 17, 2014
    #16
    I couldn't get it to easily work again this afternoon. It took a bit of fiddling with and swapping cables before it finally kicked in again. I think the technology just still really sucks. For the Macbook Pro and this Monitor, it's pretty much a terrible combination if you want to use your laptop and NOT have it plugged in. When you plug in this monitor to the macbook via USB-C (without your brick charger plugged in), the macbook dings because its getting juice, but it will not pass a video signal back to the monitor and its not enough to actually charge. I don't know why this feature is built into the USB-C and Macbook to act like that but it really blows. Not sure how people actually utilize the cable when its the only thing plugged in.

    Is there a way to make the freakin mac 'force' video through the cable or refresh the ports or something so that you can again get a signal through the cable? Why is this so hard? WHy can't the Mac handle this? It's supposed to be built in and all fancy and stuff...kinda expect more from a 4k freakin laptop.
     

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