Primary screen goes into a state where the screen constantly blinks

[dmotsinger]

After my laptop (Dell Latitude 7490) goes into screen lock (after sitting for 15 minutes…not to sleep, just locks the screen and screen goes blank), the monitor blinks off/on (you see “no HDMI input” then the screen goes off…then comes on again with the “no HDMI input” message…repeat).

Most times, when you move the mouse/keyboard the screen wakes up and all is good. However, 50% of the time the screen continues to blink. The ONLY thing that fixes it is to reboot the docking station.

Pertinent info:

• The port with the issue is the primary HDMI 4K port (but using a 1080 monitor)
• This happens whether 1 or 2 monitors is attached (one to the 4K HDMI port and one to the other HDMI port)
• When 2 monitors are attached, the second monitor (attached to the non-4K HDMI port) works fine even though the first monitor (connected to the 4K HDMI port) continues flashing
• I’ve switch monitors so it’s not the monitor
• I’ve turned the monitor off and on but this doesn’t help (monitor still flashes)
• I’ve unplugged the HDMI cable but this doesn’t help (monitor still flashes)
• I’ve replaced the HDMI cable but this doesn’t help (monitor still flashes)
• I’ve disconnected the laptop from the docking station and reconnected but this doesn’t help (monitor still flashes)
• I’ve rebooted the laptop and this doesn’t help (monitor still flashes)
• I’ve rebooted everything (monitors, laptop, wireless mouse, keyboard) at the same time but this doesn’t help (monitor still flashes)
• The ONLY thing that fixes it is to reboot the docking station.

[Joshua_H]

Hello,

Thank you for contacting Plugable support! Sorry to hear about this issue. I’d be more than happy to assist you.

Thanks for the detailed description of the problem and the things you’ve tried so far. I think our next step is to get a closer look at the system for any underlying software issues that may cause the issue.

The 4K HDMI output operates using USB-C VESA DisplayPort Alternate Mode video output, which means it’s being driven directly from the graphics card in your laptop, going over USB-C as a DisplayPort video signal, and then in the dock it’s converted to HDMI. The 2K HDMI and DVI ports use a different technology which would explain why only one of your two HDMI displays is having trouble.

I have emailed you directly with instructions on how to run and send us some diagnostic information from your system.

Please don’t hesitate to let us know of other questions.

Thanks again for contacting Plugable support and best wishes!

Joshua Henry
Senior Engineer | Product Owner
Plugable Technologies