An imaginary second monitor called "No Monitor"

[tferrin]

I have an issue where my computer thinks there is a second monitor plugged into my Cable Matters docking station. It is called "No Monitor" and has a resolution of 1280x1024. When I actually plug in a second monitor, that monitor will show up correct in addition to the "No Monitor." Additionally, the display on the real second monitor is black...although that may be a separate issue. In order to address the issue of the imaginary second display, I have attached my logs.

This issue is present regardless of whether or not a real second monitor is connected. As long as the docking station is connected to the computer, a fake second monitor appears.

I have tried this on other laptops with the same hardware configuration and I receive the same results. I also have the same results on every version of graphics driver I have used. The laptop uses Optimus technology and I have tried disabling the NVidia card, but I still receive the same results. I have also tried replacing Dell's Intel HD 5500 driver with Intel's HD 5500 driver and still receive the same results. I would appreciate any help anyone is able to offer!

[AlbanRampon]

Hello,
Would you please be able to install nVidia driver 362?
After 362 on Windows 7, nVidia has done a change preventing the loading of our DLL, making the external monitor black.
We are working around their change in our next driver v8.0 which will be made available in June/July.

nVidia driver 362 is from 1st March 2016 and is available from their website.

Kind regards,
Alban

[tferrin]

Hi Alban, I appreciate your response and help. Rolling back the nVidia driver to 362 did indeed solve the blank screen. I'm happy to have your help with that part of the problem.

However, the computer still thinks there is another monitor connected that is not physically present whenever the docking station is plugged in. I have attached the most recent results of the logging tool-where I am running NVidia driver 362.

[AlbanRampon]

Hello,
What is the model of docking station you have from Cable Matters?
What is connected on the outputs? Is there any adapter left connected?
Head 1 is read and assigned.
Head 0 has a hotplug event detected so Windows assign a monitor to it. No ID can be read from plug so "no monitor" is assigned.

If you don't have any adapter connected on the dock, I recommend you disable the monitor in the Windows Display Panel (right click on desktop, then select screen resolution) instead of having it as "extend desktop to this display".

To address this completely, here is a longer way to remove the ghost. It requires you understanding what you are doing and poses risks if you delete the wrong things, your computer may not restart. That's why I advise disabling the monitor.
1. remove DisplayLink drivers
2. user the cleaner (precedure in my signature)
3. check in the registry that HKLM\Software\DisplayLink key and subkeys are moved.
3. check in the registry that HKCU\Software\DisplayLink key and subkeys are moved.
4. Delete Windows persistence as in http://support.displaylink.com/knowl...fy-numbers-are
5. Reboot
6. Install DisplayLink driver and rediscover monitors.

Kind regards,
Alban

[tferrin]

Hello Arampon,
Thank you very much for your input and troubleshooting steps.

The Docking Station has no exterior model number. On amazon it is referred to as "Cable Matters SuperSpeed USB 3.0 Universal Docking Station with 6-Port USB Hub, Gigabit Ethernet, HDMI/DVI Output and Audio Ports." Once I take it apart, I see Y-3705PCB1.0 on the mainboard inside. Please let me know if there are other module numbers I can provide.

There is no other adapters left connected, and in fact there is only one video out on the device-A single HDMI port.

I followed your steps for a clean reinstall of the display link device and I removed the windows persistence and registry keys as you suggested. Unfortunately, that did not remove the ghost monitor. I am able to disable the ghost monitor, but of course I would like to fix things if possible, rather than do a workaround. Please let me know if you have any more suggestions.

I have attached the most recent logs

Thanks!

[AlbanRampon]

Hello,

Thank you for trying and including new logs. I had a look at the new logs with a colleague.

What is taking place is that the docking station believes a monitor is connected (hotplug detection handled during the boot of the dock).
The dock tries to read the identification of the monitor (EDID) but fails. The docks sends our Windows driver it doesn't know what the monitor supports and the driver tells Windows it has a monitor of 1280x1024 to still display an image (as some monitors can be faulty or send corrupted EDIDs).
Even if there is only one HDMI plug cabled, our chip that Cable Matters added to their design can handle more.

The issue is therefore in the docking station itself which detects a monitor where there isn't. It could be from a soldering issue, or from any other production problem.

Kind regards,
Alban

[tferrin]

Hi Alban,
Thank you very much for your detailed explanation. It was very helpful and informative. I appreciate the time you spent looking this over and will take the issue up with the original seller and/or Cable Matters.