"No Monitor" appears in Screen Resolution menu pulldown when screen attached


#1

A third screen that I connect using the USB->DVI adapter appears as “No Monitor” on the screen resolution menu.

My system has an NVIDIA GEFORCE 9400 T (Dual Head DVI) as my graphics card, which works fine with the two DVI connected, 1680x1050 screens already connected.

When I attach the Plugable adapter, it appears to install properly. I restarted the machine as requested. Then I go to the Screen Resolution screen and choose to Detect the screens and then select the third monitor (using VGA adapter) with resolution 1920x1080.It appears as “No Monitor” in the pulldown menu. If I apply these settings (to extend the desktop to this screen), the third screen appears with the desktop extended but the image is very dark.

Note that this seems to be a hit and miss proposition. If I disconnect the adapter and then try using HDMI, it appears as FPD Monitor in the pulldown and appears as expected on the screen (though it is cut off slightly at the top and bottom). Then, I disconnect from the HDMI and reattach using the VGA adapter and it works (as long as I don’t shut down). If I shut down and restart, it is back to “No Monitor”.

Please let me know if this issue is something do to with my system, a bad unit or if I am doing something wrong in the installation. When it works, it is great! But, having to go through that process each time I want to use the third screen is frustrating. Also note that I would like to use the VGA connection on the HDTV I have as HDMI is being used by the cable box.

Thank you and let me know if there is anything else that you need to hopefully resolve this.!](https://sslproxy.getsatisfaction.com/sslproxy/SWhAdDNLMG5zdGFuVGlWenmLbJDGd3CABhjZermgcystANA4T6nd0pzV0fSzBRRGOd17A4b8ZLwi6-HESbXI0nQ2UVQUxLQLH7VMvm7vCNkQcHPG0Q2JvdPM9X75bZyk9MrU2n5y-QrKRbzqD4AZfQ==.jpg)](http://s3.amazonaws.com/satisfaction-production/s3_images/348530/No-Monitor.jpg)


#2

Thanks for the quick answer!
I will try the shorter/different VGA cable as soon as I can and let you know how it goes.


#3

Hi,

I didn’t have a shorter VGA cable or another one on hand. What I did try was that same cable, connected to my notebook and the third screen and it seems to work fine. There is no “darkness” so the cable seems to be fine.

Since the cable appears to be fine, could the issue be with the Plugable adapter or some other problem with the installation? I am using the latest version of the drivers (which were posted on Dec 3).

Thanks,
–Phil


#4

Hi Phil,

It’s possible, but the datapoint that the adapter is working with an HDMI connection is some evidence away from that direction. It’s good to know, though, that the cable works on nVidia’s VGA port. By the way, what is the approximate VGA cable length? And if you use the DVI->VGA converter from the Plugable pacakge with the nVidia’s DVI out, does that still work fine (trying to isolate the difference down to the the main unit of the USB adapter)?

Thanks for the additional detail! We’ll get this figured out …
Bernie


#5

The VGA cable is standard length. It’s one of the cables from the screens I bought for my dual setup (DVI used for them), just unwrapped out of the box fresh. And, I am using the adapters provided in the box (DVI->VGA and DVI->HDMI)…
If I use the DVI->VGA adapter provided, it works only if the EDID is still present in the screen resolution pull down menu.
Also, I have been using the latest version of the display drivers.

Tomorrow, when I have more time, I will completely uninstall the Display Link drivers and reinstall. Should it matter if I have the unit connected already when I install the drivers?

Finally, could the problem be with any NVIDIA drivers?

Thanks again, especially for the replies on a Sunday!

–phil


#6

Hi Phil,

Thanks for your replies! The uninstall/reinstall probably isn’t necessary - that shouldn’t be the source of this kind of problem. I don’t think it’s a problem with the nVidia drivers, again because HDMI appeared to work properly.

One quick note: if the screen adjustment when using HDMI was the only reason not to use that connector, that one is solvable (DisplayLink drivers version 5.5+ have a nice “Fit to TV” utility/feature for TVs). But it sounds like you only have one HDMI input, so that’s why VGA is route you’re focusing on.

It’s much more often the VGA cable, but there’s still a possibility that the DisplayLink chip’s DAC is bad. To rule that in or out, I’d like to send you a second test adapter. If you can you send your amazon order number to support@plugable.com (and the address from that order is still good to send to), we can get that in the mail tomorrow to confirm by the end of the week.

Thanks for your patience working through this on a Sunday!
Bernie


#7

Hi Bernie,

I just sent the email as you requested to support. Let me know if there is anything else that you need.

–Phil


#8

Hi Phil,

Thanks for posting! And thanks for the complete info and screenshot - really helps to understand what’s going on.

The first suspect in a case like this is a bad VGA cable or a VGA cable that’s too long. Do you have any other/shorter VGA cables available that you could try on this setup? Also make sure all connections between the USB adapter and DVI/VGA dongle, VGA cable, and TV are tight.

If that doesn’t work, there’s a few other angles we can try. Just let us know how it goes.

Here’s some background on what might be happening:

When monitors (or in this case, a TV) are connected to graphics controllers, the graphics controller queries the monitor’s EDID capabilities (Extended Display Identification Data) which tells the make/model and other capabilities of the monitor, but most importantly tells the exact preferred timings and mode of the monitor, plus some backup alternatives.

Querying EDID is most reliable through a digital connection (DVI and HDMI), Through an analog connection (VGA) a bad or long VGA cable can cause the EDID to not be readable.

“no monitor” as you’re seeing is because the graphics controller hasn’t been able to get an EDID from the monitor. It works when connecting via HDMI and swapping, because it’s gotten the EDID via HDMI and then can continue using it when back on VGA.

Setting a specific mode manually, as you’ve done, should work in most cases. The fact that the screen is dark/discolored also points to a possible bad cable or loose connection there with VGA.

So thanks for first trying that shorter VGA cable and checking connections, if possible. We’ll figure out a solution here.

Thank you!
Bernie


#9