Macbook Pro 2017 - USB-C Monitor not working

[NielsO]

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.

Thanks!

 

[JohnnyGo]

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.

 

[Brookzy]

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).

 

[NielsO]

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.

 

[brazosdog02]

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.

 

[Samuelsan2001]

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.

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

 

[planetf1]

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?

 

[brazosdog02]

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.

 

[andy9l]

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

If he has the 43UD79, it should accept USB-C for 4K video, data and 60W charging.

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.

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.

 

[brazosdog02]

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.

That DOES sound stupid, but I've fixed issues with dumber ideas. I'll give it a go!

 

[NielsO]

Got it also working, bought a different cable. The Belkin usb-c to usb-c one. Apparently the Caldigit Thunderbolt cable is different from a usb-c cable. A good explanation is instructed here : https://thunderbolttechnology.net/blog/difference-between-usb-c-and-thunderbolt-3

 

[brazosdog02]

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.

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.

 

[andy9l]

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.

Haha, brilliant! Can't believe that's a thing.

 

[brazosdog02]

Haha, brilliant! Can't believe that's a thing.

It makes no scientific sense to me. Its a ***** wire. How does it's direction matter?!

Haha, brilliant! Can't believe that's a thing.

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?

 

[andy9l]

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?

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.

 

[brazosdog02]

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.

 

[techguy500]

I’m having the same issue. The Thunderbolt 3 usb c cord (below) isn’t picking up display for the monitor (below) while connected to my MacBook 2015. However, my MacBook Pro 15 is picking up the charging signal from the monitor via the Monoprice cable. This is my second cable from Monoprice as I sent it back and was sent a new one because I thought that due to it not picking up the display it was a bad cord. Any advice would be appreciated. Thanks!

-MacBook Pro 15 2018
-Monoprice Thunderbolt 3 (40 Gbps) USB-C Cable, 100W, 2.0m
-LG 43UN700-B 43" 4K

• 43” UHD (3840 x 2160) IPS Display
• USB-C with 60W PD
• HDR 10
• 4 x HDMI Input
• Multi-Tasking – PBP/PIP
• 10W x 2ch Built-in Speakers

 

[yindrameansu]

Hey guys

MBP 16" 2020 bought
LG 27UD88-W

No way to make video pass through the USB-C cable. I am using the one that comes with the MBP Charger (I have no other one). It works as charger and USB Hub (connecting usb to the monitor) so data flows, not video.

Any solution?? Thanks guys

 

[supergt]

Hey guys

MBP 16" 2020 bought
LG 27UD88-W

No way to make video pass through the USB-C cable. I am using the one that comes with the MBP Charger (I have no other one). It works as charger and USB Hub (connecting usb to the monitor) so data flows, not video.

Any solution?? Thanks guys

The cable that comes with MBP is for charging only and will not pass video through. I have a similar setup and bought a thunderbolt 3 cable on amazon. I think you can get away with a cheaper cable but I wanted a solid cable and figure I’ll use it for other purposes in the future.

 

[yindrameansu]

The cable that comes with MBP is for charging only and will not pass video through. I have a similar setup and bought a thunderbolt 3 cable on amazon. I think you can get away with a cheaper cable but I wanted a solid cable and figure I’ll use it for other purposes in the future.

Thanks for that. So I need a Thunderbolt 3 cable? Thats the name?

 

[supergt]

I believe you can also use a usb c to usb c multi use (more than charge) but it is confusing. This is what I got and it works flawlessly with the same monitor you have and my 2017 MBP:

Belkin Thunderbolt 3 Usb Type-C Cable - Featuring Usb-C To Usb-C End Connections On 3 Foot/1 Meter Long Thunderbolt 3 Cable - 20 Gbps Data Transfer Speed - Usb 3.1 Compatible 10GB/s (F2CD081bt1M-BLK) https://www.amazon.com/dp/B01CEFESRO/ref=cm_sw_r_cp_api_i_fnb3EbX25CSPN
[automerge]1591481519[/automerge]
One thing you should keep in mind is the 27ud88 may not output enough power via usb c to keep charging your 16’ laptop. I read conflicting things on this when researching monitors. With heavy use the laptop may still drain slightly.

 

[yindrameansu]

I believe you can also use a usb c to usb c multi use (more than charge) but it is confusing. This is what I got and it works flawlessly with the same monitor you have and my 2017 MBP:

Belkin Thunderbolt 3 Usb Type-C Cable - Featuring Usb-C To Usb-C End Connections On 3 Foot/1 Meter Long Thunderbolt 3 Cable - 20 Gbps Data Transfer Speed - Usb 3.1 Compatible 10GB/s (F2CD081bt1M-BLK) https://www.amazon.com/dp/B01CEFESRO/ref=cm_sw_r_cp_api_i_fnb3EbX25CSPN
[automerge]1591481519[/automerge]
One thing you should keep in mind is the 27ud88 may not output enough power via usb c to keep charging your 16’ laptop. I read conflicting things on this when researching monitors. With heavy use the laptop may still drain slightly.

thanks for that info.

i also read I may have lack of power supply. Do you recommend any other price-likescreen that would cocer that?

even if I have battery drain over time of use, will it actually hurt my battery, consistently having less power than needed to fully charge?
Any thoughts?

 

[supergt]

thanks for that info.

i also read I may have lack of power supply. Do you recommend any other price-likescreen that would cocer that?

even if I have battery drain over time of use, will it actually hurt my battery, consistently having less power than needed to fully charge?
Any thoughts?

You’d have to get a monitor that outputs 100w. I don’t think there’s anything wrong with having slight drain. It may be better for the battery than keeping it charged to 100% while working all day but I’m not sure. The worst that can happen is you eventually have to stop working for a bit to charge the battery.