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June 15th, 2020 01:00

P2720DC, Latitude 7480, USB Type-C, not connecting

I'm having problems connecting my Latitude 7480 to my Dell P2720DC monitor by USB Type-C.

I have been connecting the Latitude 7480 to the P2720DC via USB Type-C for the last few months with no problems. But this morning the P2720DC can't find the source. The P2720DC provides power via the USB Type-C cable but nothing else.

The Latitude 7480 works connecting to the P2720DC over HDMI to HDMI.

I've tried resetting the Latitude 7480 a few times (it's a work laptop and this often fixes any problems), however it didn't fix this problem.

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June 15th, 2020 08:00

@Lucy62324 

Have you tried going into the onscreen menu of the P2720DC and performing a Factory Reset?  Judging by other forum posts, that often seems to solve these types of issues.

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June 15th, 2020 08:00

Hello.

Yes, I've performed a factory reset via the on screen menu.

I get the same messages as before, once I connect the cable. "scanning..." then "No usb type c signal from your device." and finally "Entering power saving mode".

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June 15th, 2020 09:00

@Lucy62324  Ok, did your system automatically install any firmware or driver updates via Dell Update/SupportAssist or Windows Update recently?  You might have gotten an update that introduced a bug.  Other than that, I don't see any firmware updates available for the P2720DC yet.  And if you don't have another USB-C laptop to test the display's USB-C port with or another USB-C display to test your existing laptop with, it's not even clear what side of this equation the problem is on.

Actually, have you tried a different USB-C cable?  You'd need one that supported at least USB 3.1 Gen 1 (or Gen 2), DisplayPort Alt Mode, and USB Power Delivery up to 100W, all of which are optional for USB-C cables.  I realize that's a long shot, but I just a couple of weeks ago had the USB 3.0 cable running from my USB hub to my laptop go bad, and it actually took me a while to figure out because it only affected actual USB 3.0 devices plugged into the hub, while USB 2.0 devices worked fine.  I was about to throw out the hub before I realized that moving the cable a bit affected its behavior.  Simple cable swap and I was back in business.

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June 15th, 2020 09:00

I have not updated any drivers on my work computer as they wouldn't let us. I haven't installed any drivers or software on the work computer.

My personal computer is a MacBook and doesn't have drivers available that I've seen. It connects via DP so no problem there.

I have requested a new USB-C cable from Dell and that should be arriving tomorrow so I can let you know if it's the cable.

I've tried the cable with a different MacBook (not mine) via USB-C and it does not work, however does via DP.

 

Thanks

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June 15th, 2020 10:00

@Lucy62324  Ok, so then it would seem to be either the USB-C cable or the USB-C input on the display.  Hopefully it's the former, since that's obviously a much easier fix.  Just as a data point though, there have been several reports of various issues when using recent Dell USB-C displays with Mac systems, including no video, inability to run the display's native resolution, charging issues, and inability to put the system to sleep.  And in these cases, using something like a USB-C to HDMI/DP adapter resolves the issue (although you then lose USB data and power).  Since neither Dell nor Apple seems to be commenting in any meaningful detail about these issues as far as I've seen, it's not clear whose "fault" these issues are, since each device works properly when paired with something else, but in the meantime users of Mac systems and Dell USB-C displays are stuck in the middle.  So if you hadn't ALSO already seen this issue on your Latitude, then that would be a possible issue.

August 21st, 2020 22:00

Earlier today I received my U2720Q monitor and connected it to 2020 macbook pro 16" with the usb-c cable included. The connection worked for about 10 minutes and suddenly it's gone - basically USB-C charging is operational but display cannot find a signal on USB-C. USB-C to DP works but of course I got this monitor mainly for USB-c connection

Anyway, tried different cables , my windows laptop all have working usb-c to my other dell u3219q monitor. All these failed with the u2720q. I strongly suspect macbook pros are killing these monitors. Brief google searched turns up at least 3 instances

-this one (albeit with windows laptop)

-https://www.dell.com/community/Monitors/P2419HC-loses-signal/td-p/7509800

https://www.dell.com/community/Monitors/U2720Q-MacBook-doesn-t-work-through-USB-C/td-p/7569036

Note that all cases started with working set up but quickly the video signal is fried.

I just initiated my return. I hope Dell can find a solution !

 

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August 22nd, 2020 00:00

@ultrasssharp  Sorry to hear about your experience, but in the interest of getting visibility for your report and keeping existing forum threads on-topic, your post really should have been its own topic.  This thread is about a P2720DC and Latitude 7480.  Your post is about a U2720Q and U3219Q with a 16" MacBook Pro.  And even the problem scenario you're describing seems completely unrelated to the original reason this particular thread was created.

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