Win 11 Wont duplicate main screen on external monitor

Lenovo V15 Win 11 22h2 all current updates.
Connect to an external monitor and this is what the 4 options do
PC Screen only shows PC screen on the PC ; nothing on the monitor (Correct)
Duplicate screen shows PC screen on the PC; nothing on the monitor (which displays 'No Signal')
Extend Screen shows the PC screen on the PC and the extension on the monitor (Correct)
Second Screen only shows black on the PC screen; and the PC screen on the monitor

So how can I get Duplicate to show the PC screen on both PC and monitor?

Have you clicked on the monitor you want to change?

This is on my lenovo Yoga 7i laptop which has 3 monitors attached. .

Not sure why you have no signal

After forcing detection via the Lenovo “Detect” in display settings (2nd option above “Brightness” in my screenshot)
if that doesn’t work , perhaps run through the Lenovo checklist and see if you can resolve it.


EDIT: If however you can see the external monitor in your display settings, the first 2 things I would do is
1. Double check that the monitor is turned on at the power source and turned on on the monitor. (it’s an easy thing to overlook)
2. Swap cables to check that yours isn’t faulty.

Verify the settings for the monitor - usually when it cannot display a signal it is because the parameters are out of whack (like you're trying to use too high of a resolution / too low of a resolution / to high of a refresh rate.

When mirroring Windows sometimes goes stupid and tries to apply the main monitor's settings like the above to the remote monitor as well, and that usually won't work when trying to sync a laptop's display to an external monitor.

johnlgalt said:

Verify the settings for the monitor - usually when it cannot display a signal it is because the parameters are out of whack (like you're trying to use too high of a resolution / too low of a resolution / to high of a refresh rate.

Click to expand...

Quite true. @Rincewindwiz what is the monitor brand and model?

Since the other 3 methods work, It's probably either a saved setting (like in a Lenovo app that is forcing the screen resolution to the monitor resolution) or else a Lenovo setting that is overriding Windows handling of the signal when in mirror mode.

Rincewindwiz said:

Second Screen only shows black on the PC screen; and the PC screen on the monitor

Click to expand...

This is by design - second screen only means external monitor only, meaning the laptop monitor is turned off. SO, this one too is correct.

antspants said:

This is on my lenovo Yoga 7i laptop which has 3 monitors attached. .

Not sure why you have no signal

Click to expand...

johnlgalt said:

Since the other 3 methods work, It's probably either a saved setting (like in a Lenovo app that is forcing the screen resolution to the monitor resolution) or else a Lenovo setting that is overriding Windows handling of the signal when in mirror mode.


This is by design - second screen only means external monitor only, meaning the laptop monitor is turned off. SO, this one too is correct.

Click to expand...

This is indeed correct and I include it mainly to show the monitor is connected correctly and working
The "Duplicate" option is the one that is incorrect and I expect it to be a setting saved somewhere but crucially
Which Setting, Saved Where!

antspants said:

Quite true. @Rincewindwiz what is the monitor brand and model?

Click to expand...

Its actually a SANYO PLCXW20 projector.
But this seems unlikely as the "Second Screen Only" option displays perfectly on the projector as does the "extend" option.

antspants said:

After forcing detection via the Lenovo “Detect” in display settings (2nd option above “Brightness” in my screenshot)
if that doesn’t work , perhaps run through the Lenovo checklist and see if you can resolve it.

Troubleshooting Display or Monitor Issues - Lenovo Support AU

support.lenovo.com

EDIT: If however you can see the external monitor in your display settings, the first 2 things I would do is
1. Double check that the monitor is turned on at the power source and turned on on the monitor. (it’s an easy thing to overlook)
2. Swap cables to check that yours isn’t faulty.

Click to expand...

Please note the original post says
Extend Screen shows the PC screen on the PC and the extension on the monitor (Correct).
Second Screen only shows black on the PC screen; and the PC screen on the monitor so the monitor is connected correctly and working properly

Rincewindwiz said:

Which Setting, Saved Where!

Click to expand...

what is the monitor and model number?

johnlgalt said:

Verify the settings for the monitor - usually when it cannot display a signal it is because the parameters are out of whack

Click to expand...

I ask for the make and model because as John mentions, this can occur. My main monitors have a button to auto detect the correct signal. Then the monitors are set to the correct setting. I am wondering if yours does also or where that setting may be.

Thanks to all that replied

I know the monitor is connected and works correctly because, as in the original post:
Extend Screen shows the PC screen on the PC and the extension on the monitor (Correct)
Second Screen only shows black on the PC screen; and the PC screen on the monitor
In fact everything works correctly EXCEPT the option I need Duplicate (PC Screen on Monitor)

The monitor is actually a SANYO PLCXW20 projector

I have been through the Lenovo checklist. The only possible issue is the driver so I downloaded the latest driver from Lenovo but it makes no difference.

When on 'Duplicate' the monitor/projector screen flashes as if it is trying to detect a signal whereas normally it displays the signal (eg XGA) that it has detected so I presume Win11 is not sending any signal at all. Sounds like a setting somewhere so how do I fix this?

Rincewindwiz said:

I have been through the Lenovo checklist. The only possible issue is the driver so I downloaded the latest driver from Lenovo but it makes no difference.

Click to expand...

Yeah ok. I was wondering about the monitor make/model number but no worries.

OK so the problem appears to be related to the connection
If I use a projector with an HDMI connector all 4 options work fine

The Sanyo does not support HDMI input so I have an HDMI to VGA adapter. Bizarrely

• With an HP DV6 (my old computer) the connection via the HDMI-VGA adapter worked fine
• With the Lenovo V-15 it works as described
• With a Lenovo X270 it does not work at all and the projector is not even recognised/identified

But I can see no good reason why, on the V-15, the cable/adapter should affect only displaying screen 1 on the projector (as in the Duplicate option)

Rincewindwiz said:

Its actually a SANYO PLCXW20 projector.
But this seems unlikely as the "Second Screen Only" option displays perfectly on the projector as does the "extend" option.

Click to expand...

No, actually, this makes sense.

Second screen only is when Windows will adjust the display output from the GPU to match the specs of the Sanyo projector. Your primary screen is off, so Windows makes the change.

Similarly, Extend is set up to always treat the external as a separate devices, and again, Windows 11 is doing just that. It sends full capability signal to your internal screen and reduced to the projector.

The issue is with the duplicate, and Windows 11 thinking both devices are the same, and more importantly, treating them as the same.

Try changing some values for your screen since you're using that adapter (which means you're actually stepping down in terms of bandwidth as well as usable functionality, as VGA doesn't have nearly as much bw nor capabilities as HDMI), and there lies the problem. The internal screen has all sorts of capabilities and such available that the connection over the VGA adapted HDMI does not, and yet Windows it trying to send the same capabilities over to both devices, in an identical manner, that gets broken because of the adapter.

Try changing settings on your internal screen like:

• Reducing the screen refresh rate (System --> Display --> Advanced - make sure your internal screen is selected at the top)
• Reducing the resolution
• Turning off HDR

I'm betting one of the first two should make it usable as you have it set up now, without, spending any money on better adapters, or a new projector.

HTH

Interesting . . .
The Sanyo manual lists loads of acceptable signal details
If I pick one SXGA 1280x1024 the manual lists 2 frequencies
H freq 63.74; V freq 60.01
So I set display res at 1280x1024
Display->Advanced-Refresh rate only has 1 rate in the drop down box 60.01 so I set that
But there is no change in the performance of Duplicate. THe main screen still does not show on the projector.

However, in HDR (which tells me my display does not support HDR except video streaming), it does allow me to pick a display (internal or wired which disappears when I unplug the projector) to adjust HDR. But its set to off for both displays

When adjusting the frequency in Windows. it's always the VFreq unless it specifically says otherwise.

I found the manual for your device online.

This is what it says regarding compatible resolutions:



FWIW, it does not even show higher resolutions, but it does show quite a few VFreqs it supposedly supports.

Since you have the manual, the above is from page 23, be sure to go through pages 22-29 (You may need to do this when it is in Extend mode, as I don't know if the OSD works when it is blanking out like that on Duplicate mode).

Also note the info on page 111, about the reset button - it specifically says it may need to be used periodically, and it may not be a bad idea to try it if you already haven't.

Thanks for looking all that up.
I did already try SXGA 1280x1024 with a V Freq of 60.01 (the only Freq that the laptop lists) but it makes no difference
I have now also tried resetting the projector but that too has made no difference.

Its clear from the fact that the screen changes briefy when the projector is plugged in) that the PC is aware there is another screen attached
Its also clear from the fact that the HDR setting offers a choice of monitors
System->Display Multiple monitors shows 1|2 but cannot detect another monitor (presumably looking for a third so thats OK)
But this second monitor does just not get used in Duplicate
.
Its clear that the projector understands the signals the PC is sending because extend & show on 2 work so all the complicated stuff about manual setting of the Frequencies wont help
When "Duplicate" is selected, the screen momentarily shrinks and then returns to its original size so the PC is trying to do something

So Why does the PC send screen 1 to the projector in "show on 2" but does not send it in "Duplicate" ?
Sounds like a Windows setting to me but what and where?

Rincewindwiz said:

so all the complicated stuff about manual setting of the Frequencies wont help

Click to expand...

Only if you can verify that it is using the same frequencies and resolution across all three modes.

Windows 11 is very big on auto-adjusting specs and settings in order to make it easier for the user, who then doesn't have to do all of this manually. The upside is that is makes it easier for most end users to simply plug things in and start using them.

The downside is that sometimes it invokes parameters that are not actually usable, and this is where user intervention is required.

I used to use a pair of 1080p monitor,s then I got my first 4K monitor, and replaced on of them. I cannot tell you the shenanigans I had to go through because early Windows 11 would try to make all my content show at 1080p (and resulting in ugliness on the 4K monitor), or would try to force a 4K resolution to the 1080 monitor (resulting in it showing the black screen).

I've been there. You have to be on top of the ball with Windows 11 when it comes to mixed resolutions every once in a blue moon. Most times (I'd venture 90% or even higher) it works fine. But every now and again a particular combination of devices causes it to do things strangely, as I've seen in the past and as you're possibly (I say probably) seeing now.

Rincewindwiz said:

So Why does the PC send screen 1 to the projector in "show on 2" but does not send it in "Duplicate" ?
Sounds like a Windows setting to me but what and where?

Click to expand...

That is the issue - it is sending it. But because it is in a format the projector cannot display, it goes all black.

If you were to start playing with the resolutions on your laptop's screens, and were to pick something the screen cannot handle, it would do the exact same thing - turn black.