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04-18-2020

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C940 not charging with Thunderbolt 3 Gen 2 dock

2020-04-18, 22:11 PM

I've been having a problem with the dock not recognizing that a display is connected. I updated the driver and firmware and now it recognizes the display, but has this bug:

 

(1) When the dock is plugged into the first UBC-C port (the one in the back, next to the USB port), the peripherals connect but the laptop wouldn't charge.

 

(2) When the dock is plugged into the other USB-C port, the the laptop charges but none of the peripherals connect.

 

I need the dock to do both of those things. As far as I can tell, this problem occurred with the firmware update. I'm prepared to return the dock and find another solution. Has anyone encountered this?

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2 Posts

04-18-2020

United States of America

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Re:C940 not charging with Thunderbolt 3 Gen 2 dock

2020-04-18, 22:35 PM

OK, update: After playing around with it a few times, here's what's happening:

 

When the dock is connected to the second USB-C port, everything works the way it's supposed to. The computer now charges, and the peripheries stay connected, AND it recognizes that a display is connected. Everything works, hallelujah.

 

When the dock is connected to the first USB-C port (the one nearer to the back of the computer), the peripheries are connected, it recognizes the display, BUT does not charge. In other words, it's only charging from the second USB-C port.

 

I checked the manual and nothing indicates that there's a difference between these two ports. At least one of them is working, but I'd love for the other one to charge as well.

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1 Posts

02-06-2020

Australia

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Re:C940 not charging with Thunderbolt 3 Gen 2 dock

2020-04-26, 11:50 AM

Hi Tien T,

 

Yes that is exactly the same issue I am having.  

 

Initially things were OK then I updated the firmware on the dock and now have the same problem. I have heard no response from Lenovo from these forums.  My original message can be found in the following thread:

 

https://forums.lenovo.com/t5/Lenovo-Yoga-Series-Notebooks/Yoga-C940-power-delivery-interrupted-when-using-any-source-other-than-direct-from-power-adapter/m-p/4636685?page=1#4641727

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3 Posts

05-11-2020

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Re:C940 not charging with Thunderbolt 3 Gen 2 dock

2020-05-11, 18:24 PM

The very same thing happened to me. Yoga C940 and the thunderbolt 3 dock gen2. No charging on the 1st USB-C port but do on the 2nd. Moreover, the external displays are not reactivated automatically after the system sleeps. I need to put out and on the USB-c cable every time. Please update us if you have new finding on these issues. Cheers!

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1 Posts

05-11-2020

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Re:C940 not charging with Thunderbolt 3 Gen 2 dock

2020-05-12, 0:55 AM

My C940 is doing exactly the same following the FW update. It is as though the TB/USB-C charging ports are swapped after the update requiring you to plug into the port closest to the headphone jack. Displays & peripherals work as expected but displays still do not wake after sleep without unplugging/re-plugging  the docking cable. 

I make the IT purchasing decisions for my company, and while I really like the C940, given the >$3700 price for the system and peripherals, there is no way we could advise switching to Lenovo until these docking issues are resolved.  

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41 Posts

02-21-2020

Switzerland

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Re:C940 not charging with Thunderbolt 3 Gen 2 dock

2020-05-12, 6:36 AM
Are you referring to C940 15" or the smaller version, the 14"?
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3 Posts

05-11-2020

United States of America

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Re:C940 not charging with Thunderbolt 3 Gen 2 dock

2020-05-13, 17:50 PM

For me? it is 14" C940.

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4 Posts

02-24-2020

United States of America

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Re:C940 not charging with Thunderbolt 3 Gen 2 dock

2020-07-01, 20:16 PM

Hi.

Tien T, Which C940 do you have? 14 inches or 15 inches?

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10 Posts

07-04-2020

Australia

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Re:C940 not charging with Thunderbolt 3 Gen 2 dock

2020-07-09, 7:26 AM

Same problems here (both charging from the back port and reconnecting to the monitor after sleep). I have a C940-II14 and the ThinkPad Thunderbolt Gen 2 dock with the very latest firmware.

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1 Posts

07-13-2020

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Re:C940 not charging with Thunderbolt 3 Gen 2 dock

2020-07-13, 6:40 AM

+1 I have the exact same issues. I have the C940 14". Connected monitors (via DP) and webcam (via USB) works on both USB-C ports. But, the laptop only charges on the second port and not the first. As well, upon sleep, cable needs to be unplugged / plugged in to wake.  

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