TV Doesn't Recognize HDMI Output

I’m in the process of setting up my laptop to replace my old desktop computer. Everything else has gone smoothly, but this one has me stumped.

On my old desktop (running Windows 7), I had an HDMI cable going directly from the video card to the TV. No special setup was required, and I simply had to use the “Input” button on the TV remote to change the TV to “HDMI3” and I could see what was on the computer monitor. I could even get the computer’s sound to play on the TV if I changed the default sound device. The only time the “HDMI3” input choice was grayed out was when the computer was off.

But with my new setup for the laptop (running Windows 10), I’ve plugged the same HDMI cable into the docking station, but the TV doesn’t let me change the input to “HDMI3” - it’s always grayed out.

I also have my regular monitor now hooked up to the docking station, using the DVI port, and that works fine.

Hardware details:
Docking Station: Plugable DisplayLink UD-3900 (brand new!)
Laptop: Toshiba Sattelite C55-C5241, Windows 10
TV Set: LG 42LK520, 1080p resolution

So, is it possible to get this working? It’s annoying that it works with the old setup but not with the new. And if you need any more details, or for me to test out a few ideas, please let me know. I’m happy to participate in troubleshooting.

Thanks for your help.

Hi Aibohpphobia,

Thank you so much for posting, I would be happy to Assist!

One of the first things I think we should attempt to do is rule out the HDMI port on the UD-3900 dock having any issues. Does the other external monitor you are using (Plugged into the DVI port on the dock) have an accessible HDMI port? If its possible, I would try plugging the second external display into the HDMI port, and see if it displays out correctly.

Thank you for your patience and help working through this issue!

  • Marc
    Product Owner & Technical Support

Okay, I tried to use a HDMI cable to connect the monitor to the UD-3900 and it worked just fine.

After that, I was going to try a different HDMI cable, to rule out a problem with the cable. But now every time I try to plug and HDMI cable into the HDMI port on the UD-3900, the image on the monitor changes - the wallpaper is different (I have rotating wallpapers, and it’s one of the other ones), open windows aren’t visible, and the mouse pointer isn’t visible. It’s as though some information from when the monitor was hooked up via HDMI got cached somewhere.

I even tried unplugging the UD-3900 for about 30 seconds, but that didn’t help.


Hi Aibohpphobia,

Thank you for trying out those steps and locating the problem! Most likely what is occurring is when the system is connected to the dock, the orientation of the screens, as well as the “Main Display” is being lost, This can occur due to the nature of using a TV as a monitor.

What I would advise to do is connect the HDMI to the dock, then open your display settings and identify and adjust the orientation of the screens, and correctly change the main display to your desired monitor, whether internal or external. We have a couple of videos regarding these concepts located here:……

These reviews should allow you to configure the additional displays based on physical orientation, and main display usage,

Thank you,
Product Owner & Technical Support

Hi, Marc

Thank you for posting those links. I already knew some of it, but it turns out I hadn’t really thought it all the way through.

You were right - the symptoms I was seeing were caused by the display settings trying to “extend” the desktop to a second monitor, which certainly looked like something was missing.

Unfortunately, what I was really trying to do was trying to have three identical screens - one on the laptop screen (when it’s not hooked up to the docking cradle), one on the desktop, and one on the TV screen (mostly for streaming.) But Windows apparently maxes out at two. Not to mention the different resolutions, which I hadn’t even considered. (On my old setup, I could use the same one.)

I have to say your UD-3900 handles the transition from using laptop peripherals to using my computer peripherals very elegantly.

I certainly appreciate your taking the time to help me with a problem (or perceived problem) that turned out to have nothing to do with your product. That’s good customer service.

Thank you.

HI Aibohpphobia,

Thank you for watching the videos and relaying the information you found regarding your setup! I am sorry that you are not able to get your directly desired setup.

Although I wish there was more we could do when it is a limitation regarding the OS, I am glad that the dock itself is performing well.

Thank you for posting all of this great information!

  • Marc