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6 Posts

06-20-2020

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Yoga C940-14IIL jiggling external display over usb-c

2020-06-20, 1:32 AM

I have the Yoga C940-14IIL with the i7-1065G7.

 

When I connect a Dell USB-C monitor (U2719DC QHD or U2790Q UHD) to either of the two Thunderbolt 3 ports; the monitor works fine in the beginning. The laptop will also charge over the USB-C cable as the monitor provides power. Sound also comes thru the external Dell monitor.

 

However, some time later, 5 minutes, an hour, 4 hours later, it varies, the monitor will all of a sudden start to dance or flicker. It doesn't flicker on and off, but everything starts jiggling left and right. The entire screen starts dancing. To make it stop I need to either reboot the laptop or turn off the monitor and turn it back on; but usually within a couple minutes it starts dancing again.

 

It's completely unusable with an external usb-c display.

 

It's only the external display that is flickering, never the Yoga built-in display.

 

Thru the monitor info of the Dell display, I see the signal is using 59Hz. I can choose 60Hz in the intel graphics driver, but it always goes back to 59Hz.  I'm on the latest Win10 version 2004 and have the latest Intel graphics driver 26.20.100.7372

 

My daily driver laptop is a corporate Dell 2-in-1 that also has TB3 ports and it works fine with the same Dell displays.

 

I want to use my Yoga like a desktop computer with external display.

 

I called Tech support .. they had me update the display driver which did nothing.

 

How do I fix this? 

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6 Posts

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Re:Yoga C940-14IIL jiggling external display over usb-c

2020-06-20, 2:11 AM

Oh, the other issue is when the laptop wakes from sleep the audio no longer is able to go thru the monitor.  The speaker icon down by the clock doesn't have a pulldown list to choose the audio device. Need to turn the display off and on to get audio back thru the monitor.

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7 Posts

01-05-2020

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Re:Yoga C940-14IIL jiggling external display over usb-c

2020-06-21, 19:33 PM

I have the same laptop and the monitor. and just tried to connect them. I have the monitor mainly for my WFH setup. Works with no problems with DELL laptops. I have a neat setup with a vertical laptop stand and a single cable solution. logitech usb dongle attached to the monitor for a wireless keyboard and mouse. 

 

First changed the power settings C940-14IIL so that it does not go to sleep when the lid is closed. Then tried these (the latter worked)

 

  1. plugged the laptop (while the lid is closed) to the usb-c cable directly. As you said the display is fine for a second then immediately turns to garbage.
  2. plugged the laptop while the lid is open. It duplicated the display fine. then closed the lid. voila no flickering. Also manually installed dell monitor drivers.
    • Did a restart, worked fine.
    • Unplugged usb-c cable and plugged again in this closed-lid state, worked fine. note that the internal laptop display seems disconnected at this state. I was expecting this to fail since it is similar to 1.

 

It hasn't been an hr yet so not sure if it will go back to garbage. laptop seems to be charging fine. Not sure if this is a Lenovo-Dell incompatibility or a port standart issue: YOGA ports are thunderbolt-3 while the DELL input is only regular usb-c. 

 

year 2020 still dealing with these issues :/ why can't these companies sit down together and commit on the same standards. instead of quality/price consumers have to figure out a compatibility matrix when purchasing electronics.

 

 

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6 Posts

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Re:Yoga C940-14IIL jiggling external display over usb-c

2020-06-23, 0:17 AM

Here here .... that's what I want to do.

 

I have those power settings too, including the dell display manager software installed on my Yoga. I also wish the brightness keys on the keyboard would work on the external display .... why does only Apple make this sort of thing work?

 

I've tried all sorts of things. I even tried a lenovo 4 port travel usb-c dock that has HDMI output to the Dell monitor .... that combo also starts flickering like mad after some amount of time.

 

I like the Dell monitors because they have the USB ports on the side for easy access. No other display manufacturers have this. The monitors NEVER go bonkers with the Dell laptop I'm using.

 

Today I've had my Yoga sitting off to the side all day long with it's lid closed. I unplugged my dell laptop from the USB-C cable and plugged it into my Yoga C940. The Dell display lit up just fine and let me start using the Yoga C940 right away and it is the only display shown in Settings / System. It's been fine for like 20 minutes now. But eventually and there's no telling when it starts acting up, the display will eventually turn to garbage. If I walk away for a bit and the display goes to sleep (why would one NOT want to sleep the display if you walk away) when I get back to the Yoga, tap the keyboard to wake up the display or laptop the display comes to life but no audio thru the display. 

 

Lately I've been finding that once it starts jiggling. If I turn off the display and back on (with the display power button), it's fine for only a few minutes before the jiggling comes back.

 

I too have been doing WFH since March 16 and do a lot of MS Teams conference calls. When I have a bluetooth headset connected and a bluetooth mouse paired with the Yoga the audio is fine but the mouse gets all laggy as heck. 

 

Imagine ... mankind can launch into space all automated and have a rocket land itself on a floating pad bobbing in the ocean but we can't figure out USB interoperability with displays.

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15 Posts

01-02-2020

DE

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Re:Yoga C940-14IIL jiggling external display over usb-c

2020-06-28, 9:52 AM

I have a similar problem with my Dell 2419hc monitor. Tried two different 2419hc with two new thunderbolt cables.

 

It seems like the C940, or at worse the whole C-2019 Icelake model range, have sever problems with their thunderbolt/USB-C/charging functionality.

 

If my C940-14 is connected via USB-C with my Dell 2419hc (charging through it) AND the lid is closed, after a few minutes/hours the whole screen will become unreadable. It looks extremenly grainy, nearly like a privacy filter. If i pull the cable / restart the monitor it resumes to normal but after a few seconds/minutes it happens again. After i restart my C940 it normally works fine until it happens again, mostly, a few hours later.

 

I have updated my thunderbolt 3 driver. Currently on driver version 1.41.823.0. No change at all.

 

It has nothing to do with the 59/60 hz.

 

 

Just another problem with the USB-C/Thunderbolt functionality. Besides the problems with charging, supported/working thunderbolt 3 Docks and ethernet dongles (random disconnects and drops down to only 100mbit/s).

 

 

Edit: The whole problem doesn't happen at all if the C940 is open, it only happens if the lid is closed.

 

 

 

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7 Posts

01-05-2020

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Re:Yoga C940-14IIL jiggling external display over usb-c

2020-06-29, 3:11 AM

If you first connect while the lid is open then then close the lid and keep on using it, do you still have the problem?

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15 Posts

01-02-2020

DE

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Re:Yoga C940-14IIL jiggling external display over usb-c

2020-06-29, 11:29 AM

Yep, same problem.

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6 Posts

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  • Message 8 of 9

Re:Yoga C940-14IIL jiggling external display over usb-c

2020-06-30, 2:11 AM

Lately I've been plugging it in while the lid is closed and it's been kinda sorta ok, but not perfect. I have 2 external monitors, a Dell 2419HC daisy chained via DP cable to Dell 2719DC with the Yoga connected to the 2719DC via USB-C. It hasn't jiggled in a few days now but again, I haven't used it much these past days. What does happen sometimes is the 2419HC will turn off, then on, then off, then on .. keeps cycling until I reboot the Yoga C940.

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  • Message 9 of 9

Re:Yoga C940-14IIL jiggling external display over usb-c

2020-07-06, 19:00 PM

For me: plugging it in while the lid is open then close it, does the trick. But of course I wish we didn't need this trick :/

 

My work laptop from dell is working seamlessly plugging in while it is sleeping and lid closed, it has no problem waking up as soon as plugged in and display is stable.

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