External Monitor recognized, but won't display

[couldbeworse]

I am trying to connect my T540p to an external HP monitor via VGA to HDMI cable, since my Thinkpad doesn't have an HDMI port. As soon as I connect the cable, the laptop makes the sound when a device is connected, and seems to change into the bottom screen of a 2 screen system, however the monitor never detects the laptop. I have tried updating, uninstalling/reinstalling, and rolling back (not even an option) the drivers, but nothing seems to work.

Has anyone had similar issues?

[dr_st]

Welcome to the forum.

VGA to HDMI is probably the worst way to connect an external digital monitor. It requires an active converter, and you are still limited by the quality of the analog signal.

I don't know which adapter cable you have, and whether that can even work.

Use a mini-DisplayPort to HDMI instead.

[pianowizard]

If this really is a VGA-output-to-HDMI converter, it should require power since it would need to be *active* as dr-st mentioned, most likely from a micro USB or USB-C port. Here is an example on Amazon:

https://www.amazon.com/FOINNEX-Converte ... 07121Y1Z3/

You can see in the top photo that this converter has a micro USB port. Check if yours also has a micro USB port. If it does, you need to plug it into your T540p's USB port via a micro USB / USB-A cable. Obviously, if it has a USB-C port, then you would use a USB-C / USB-A cable.

If you don't see a power port, then this is almost certainly an HDMI-output-to-VGA adapter, not VGA-output-to-HDMI. Instead of buying a VGA-output-to-HDMI converter, get a mini DisplayPort-output-to-HDMI adapter as dr-st suggested.