U2719DC, XPS 15-9550, USB Type-C not working

* When did you purchase this U2719DC?
* From whom did you purchase this U2719DC?
* Click my name and private message me the U2719DC service tag number and 20 digit serial number

* U2719DC is off
* XPS 15-9550 is on, AC power adapter attached to it, lid is open, you can see the Windows desktop

* Connect like this =
XPS 15-9550 left side TB3/USB Type-C out port --> U2719DC USB Type-C cable (C to C) --> U2719DC USB Type-C in port
* Turn the U2719DC on
* Press the U2719DC #2 Input Source button
* Check USB Type-C
* Exit the Menu
* Open the XPS 15-9550 Display settings and Extend to the U2719DC

* So this works to get 2560x1440 60Hz?
XPS 15-9550 left side TB3/USB Type-C out port --> USB Type-C cable DA300 USB Type-C --> DP to DP cable --> U2719DC DP in port

* When connecting like this, did you then press FN+F8 to switch to the U2719DC?
XPS 15-9550 left side TB3/USB Type-C out port --> U2719DC USB Type-C cable (C to C) --> U2719DC USB Type-C in port

 So this works to get 2560x1440 60Hz?
XPS 15-9550 left side TB3/USB Type-C out port --> USB Type-C cable DA300 USB Type-C --> DP to DP cable --> U2719DC DP in port

Yes

* When connecting like this, did you then press FN+F8 to switch to the U2719DC?
XPS 15-9550 left side TB3/USB Type-C out port --> U2719DC USB Type-C cable (C to C) --> U2719DC USB Type-C in port

Yes, I only have this message : "No USB type-C signal from your device"

I do not think that the new U2719DC USB Type-C in port is faulty. But you do not have any other devices there with USB Type-C out port to test on.

Moving this thread to the XPS Laptops board in hopes that other XPS 15-9550 can add their thoughts, troubleshooting, etc.

Actually, one basic question in addition to the possibility I suggested above: What type of USB-C cable are you using? The cheap USB-C cables only have wiring for the pins that carry USB 2.0 and power because those cables are meant for charging devices and/or simpler data transfer use cases. To carry video, you need a USB-C cable that supports at least USB 3.1 Gen 1, since that means the cable has wiring for the pins that make up the four high speed lanes, which can be used for carrying either USB 3.1 data or video.

This exact behavior was reported by several users across 3 separate threads here about the XPS 13 9350, which is the generational sibling of the XPS 15 9550. Dell eventually issued a KB about it, which basically said that that system and certain Dell USB-C displays didn’t work together when using the USB-C input on those displays, and that Dell had no intention of fixing it. They did not even identify the underlying problem. Link: https://www.dell.com/support/article/us/en/19/sln314862/xps-13-9350-no-video-with-dell-type-c-monitors?lang=en

So yes, video output from the USB-C port works, and the USB-C video input on those Dell displays works (with other devices as the video source), but the specific combination of that system and the USB-C input on those displays is a problem. I’m betting the XPS 15 9550 has the exact same issue and it wasn’t addressed in the KB simply because none of the threads that led to that KB involved a 9550.

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@alexsch wrote:

Hi, Thank you for the detailed information! The cable I use is the one provided with the U2719DC screen. It is able to transmit video as described in this page : https://www.dell.com/en-us/shop/accessories/apd/210-arcz It is very disappointing if this problem cannot be resolved.

when we buy only dell devices, we are expecting they are fully compatible!
Dell never tested the 2019 U2719DC monitor on this old 2015 laptop. Which is why I moved it over here to see if other older, out of warranty laptop users had tested it. DELL-Chris M

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Ok, then it's not a cable issue, in which case your system is most likely affected by the same issue described in the KB article for the XPS 13 9350.  I agree that the lack of commitment to interoperability is disappointing given that this issue involves entirely Dell products.  Same goes for the KB's claim that the XPS 13 9350 is EOL (end-of-life), even though it only stopped being the current generation system about 2 years before the KB was published, which means many of them will still be in use.  But maybe it's a hardware issue and therefore can't easily be fixed with a driver/firmware update.  Unfortunately, given that Dell has chosen not to provide any sort of technical explanation as to underlying cause, there's no way to know.

I have to say I am really disappointed that Dell will not support their older laptops. What a shame.

I had online conversation with Dell support before I buy Dell U2419HC monitor last week, and they told me it will work with my XPS 15 9550. I bought it directly from Dell website.
Now it's not working. I have two Dell devices which are not supporting each other.! (MacBook Pro is working with same monitor, same cable)

Hello jpgughan

I have the exact same issue with my XPS 15 9550 and U3219Q monitor. I'm using HDMI-HDMI right now, but like this it is only possible to get 30 fps. To get to 60 fps I have to use the USB c port. 

On the website, where "solutions" are listed, they only say that docking stations are a way to get a connection (https://www.dell.com/support/article/ch/de/chbsdt1/sln314862/xps-13-9350-no-video-with-dell-type-c-monitors?lang=en).

My question is, can't I just use a dongle (USB C to HDMI or USB C to DisplayPort)? Will the problem of "not working together" stay the same or will it be the solution to get 60fps at 4k?

@alexsch How did you fix the problem?

Thank you guys!

Thank you for your response jphughan!

Since Dell has listed just two dock stations as a solution (https://www.dell.com/support/article/ch/de/chdhs1/sln314862/xps-13-9350-no-video-with-dell-type-c-monitors?lang=en) I asked this question also to the Dell guy who tried to help me with the problem. The discussion is in German:
https://www.dell.com/community/XPS/USB-C-Probleme-beim-Monitoranschluss-an-XPS-15-9550/m-p/7318105#M3494
His response was that only the station will help, so a dongle won't fix the problem, as he says.
I started to look for the TB16 after his informations (too expensive!!!) but now I'm not sure anymore whether his answer was correct.

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because several users have confirmed that both the XPS 15 9550 and the XPS 13 9350 (the subject of the KB) work fine using USB-C to DisplayPort cables, even when used with the Dell USB-C displays. 

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Where have you seen the confirmation of the users that the XPS 15 9550 works fine using an adapter?