Laptop's HDMI output sending only blue screen to projector

[Eumaios]

Hello,

When I taught at school before coronavirus, I used to plug an HDMI cable into my laptop, and the machine in the classroom would share my laptop's screen image through the projector. Now, almost two years later, when I tried to do that again, the projector showed only an empty blue screen.

I tried a colleague's laptop, and the projector worked fine with that other laptop. I tried my laptop again, and it still didn't work. Just the blue screen. We tried switching projector inputs. We tried rebooting both laptop and projector in various orders. We tried uninstalling and reinstalling my video driver. Nothing worked. But my colleague's laptop worked fine.

I think my HDMI output is functional. When I enter Settings on my laptop (Start -> Settings -> System -> Display) while the HDMI cable is connected, I get a blue rectangle on the Display settings page that has a "1/2" displayed on it. When the cable is unplugged, that disappears. Also, only when the HDMI cable is plugged in, I have additional options on the Display settings page, about what to do with the second display, such as mirror the primary display. Those options disappear when the cable is unplugged.

Thus, I wonder, are there any settings in the operating system that would disable the HDMI output? A few weeks ago, I changed a number of settings in Settings -> Privacy to disable unnecessary reporting to Microsoft and to disable unnecessary sharing of system resources with apps. Perhaps one of those settings also disables screen sharing over HDMI? I've looked through them and tried changing back quite a few, but nothing is helping so far.

Or--any other suggestions.

I would greatly appreciate any help that you can offer!

Sincerely,
Eric

 

[Grizzly]

is the HDMI your primary output? a blue screen on the projector means usually that the projector does not get a signal.

I get a blue rectangle on the Display settings page that has a "1/2" displayed on it.

That tells me that your HDMI is working the way it is suppose to do. Now you just have to tell your laptop to send a signal to the HDMI.

I have additional options on the Display settings page, about what to do with the second display,

Which option did you choose. Looking at them will not change anything (forgive me my sarcasm, I had a long day)..
If you set the laptop to mirror your screen, the same video should show on the projector.
BTW: is the projector recognized in the device manager?? if not, it might not be able to handle the resolution and/or refresh rate of your laptop.

This is at the moment all I can throw at you, might be able to think of something else....

 

[Eumaios]

Your sarcasm is understandable. I'm just grateful for your offer of help.

Yes, I set the option to Mirror my laptop's screen.

I will take my laptop to the classroom again and test to see whether the projector is recognized in my device manager. I hadn't thought of that; thank you. I did try reducing my laptop monitor's resolution from 2560 x 1440 at 60 Hz to 1920 x 1080 at 60 Hz, but that didn't help.

I'll let you know about the device manager.

Thank you again,
Eric

 

[windows user]

in settings app for laptop go to display settings and select the drop down menu and hit mirror primary display. by the way does the blue screen have task bar or is it literally all blue no response at all.

 

[Eumaios]

Hello,

The projector screen is literally all blue. When it first displays, there are some other boxes and information there, but that is displayed by the projector and soon disappears.

I tried attaching the laptop again yesterday, and there's no exact option for mirroring using that word, but the first option is to "duplicate" the main monitor on the secondary monitor. I assume this must be the mirroring option. Anyway, I selected it. It doesn't help.

I tried also moving the main display onto the secondary display. In that way, my laptop's display went black, but the projector still remained blue.

Finally, I checked the device manager while the projector was attached, but I found no entry for the projector. In which category should it appear? I looked through every line but couldn't find anything about a projector.

Thank you,
Eric

 

[Grizzly]

Finally, I checked the device manager while the projector was attached, but I found no entry for the projector.

That tells me that your laptop and the projector are not communicating. Can you connect a TV to your HDMI and find out if it works??
That would give an indicator of what is going on. If it does not work there either, I can only assume that your HDMI port is bad.
Since your colleagues laptop works with the projector, we can rule out cable issues or projector issues.

BTW: the projector should appear in the device manager in the section 'display'.

 

[windows user]

Good idea.