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MIBrus
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Posts: 2
Registered: ‎01-16-2019
Location: RU
Views: 2,446
Message 1 of 2

Ideapad 720S-13IKB 81BV Type-C DP (Alternate mode) still doesn't work

Hello everybody! Need help with this old problem with connecting to display (monitor) through Type-C 3.1 (Thunderbolt 3) on Ideapad 720s-13IKB (81BV) - my configuration is 8250u i5 version with 13" FullHD screen, 8gb ddr4 and 256 NVME SSD.

 

I've bought new Dell monitor U2419HC (https://www.dell.com/en-us/shop/dell-ultrasharp-24-usb-c-monitor-u2419hc/apd/210-arcy/monitors-monit...) with native support of Type-C connection (so I don't need any HDMI/DP adapters), but I can't get video signal to work - it's charging my ultrabook (PowerDelivery is working like a charm) and integrated USB-Hub is working flawlessly, but I have "No signal USB Type-C" message on display and "Display connection might be limited" (https://support.microsoft.com/en-us/help/4012609/windows-10-fix-usb-c-problems) Windows message when I'm connecting my Dell to ultrabook.

 

I've spent about 5 hours trying figure it out, read dozens of forum threads (including marked "Solved") this ones:

 

https://forums.lenovo.com/t5/Lenovo-Yoga-Series-Notebooks/Yoga-720-USB-C-to-HDMI-Not-Working/td-p/39...

https://forums.lenovo.com/t5/Lenovo-Yoga-Series-Notebooks/Yoga-920-USB-C-to-HDMI-not-working/td-p/38...

 

Updated everything - BIOS (to December 2018 6MCN30WW), Intel UHD 620 to Lenovo's last (August 2018), then to Intel's last version (December 2018), last Windows 10 update - still no luck.

I'm using type-c->type-c cable that comes with Dell U2419HC, and it's work's with my smartphone (LG V30+) - I have video signal and PD charging at the same time, so cable is 100% working.

 

I ask you for help, 'cause now I haven't any ideas why this setup doesn't work as it should. Thanks in advance for your help!

MIBrus
Fanfold Paper
Posts: 2
Registered: ‎01-16-2019
Location: RU
Views: 2,364
Message 2 of 2

Re: Ideapad 720S-13IKB 81BV Type-C DP (Alternate mode) still doesn't work

I ask - I answer.

While our Lenovo support is out of duty on weekend, I've found soluthion - bought Type-C->DisplayPort adapter (Gembird Cablexpert USB-C to Displayport A-CM-DPF-01) in local store, which, to my suprise, got it to work with supplied DP->DP cable! (So Dell USB-C - DisplayPort (470-ACFC) adapter could be also a working solution, I just haven't found it on stock in the nearest stores yesterday).
This is the most easy, but not esthetic soluthion, 'cause now I have both of my Type-C ports occupied (1 with charging and USB-hub function, 1 with video signal output).

I still can't understand, why it doesn't work with "1 cable to rule them all" (Type-C->Type-C), as it supposed to be. I have looked once again at supplied Type-C cable, and found lable "Type-C Gen2" on it, also I've found approvement on Reddit, that supplied Type-C cable works for video, charging and data-transfer (USB-Hub) same time - https://www.reddit.com/r/sysadmin/comments/9f0gvz/dell_usbc_monitors/ (see "EDIT" on the top of first message). So supplied cable is good, and it can't be the reason of my trouble. But the fact that adapter works approves that DP alt. mode over Type-C works on my Lenovo Ideapad 720s, and why it can't deliver signal through Type-C cable is mistery for me...

Also one strange thing I've noticed - I was getting "Connection limited" warning when I was connecting Type-C cable to the far from me Type-C Port, which by the manual is just for charging (so it's not USB 3.1/Thunderbolt 3/DP 1.2 compatible), as in near to me Type-C port I've got nothing - no signal, no warning. But adapter worked in nearest post, while far port now acts for charging and USB-hub data transfer.

If anyone have any thoughts about this situation, it will be very interesting for me to listen.

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