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16 Posts

12-19-2019

PL

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Yoga C940-14ILL - automatic brigthness issue and whitish screen after logging in

2019-12-23, 13:00 PM

Hi everyone,

 

I have two annoying problems with my new Yoga C940 with 4k screen (other than noisy whining):

 

1. I can't turn off automatic brightness. I mean, it's turned off, but the screen still gets darker and brighter. I've updated Iris drivers to the latest ones (using method described here). In the new Intel Control Panel I can't find an option to disable energy saving by dimming the display. Do you have any ideas whatelse could I check to turn it off?

 

2. Sometimes after logging in (from locked Windows) my screen appears to be whitish. I tried to make a screenshot but apparently everything is fine on the picture. Some text, checkboxes, other visual elements get super bright and the only thing I can do is to restart Windows. Does anybody else have that issue? I'll try to make a photo of my screen next time the problem appears.

 

Thanks for any suggestions.

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11 Posts

12-23-2019

US

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Re: Yoga C940-14ILL - automatic brigthness issue and whitish screen after logging in

2019-12-23, 17:21 PM

As a C940 15" user, the automatic brightness you are decribing I think is dobly vision, if I am correct. I am unsure how to change its settings as the dropdown is greyed out for me in the Dolby Vision app.

 

As for your white screen issue, I am having the exact same problem. It only occurs sometimes for some reason and I haven't figured out what is causing it. It is quite frustrating when it does happen because a restart does not seem to solve the problem. (See Edit)

 

Hopefully somebody out there has an answer.

 

EDIT: I am unsure if this is just a coincidence but earlier when I powered it on and got the whitish screen, I was running on battery. I also tried restarting on battery before which did not solve the issue. But, I just plugged in my laptop and when I restarted with it plugged in, the issue went away. Again, not sure if that was a coincidence.

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32 Posts

07-03-2019

DE

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  • Message 3 of 18

Re: Yoga C940-14ILL - automatic brigthness issue and whitish screen after logging in

2019-12-23, 20:29 PM

Hi there -

 

I noticed the same problem soon after getting my C940. It seeems to be common to many other PCs

 

Until Lenovo lets us access the setting via the Intel Graphics Command Centre/Control panel, you have to go into Regedit.

 

The instructions are here. The one difference is that the value you change is 200 to 210 and not 8200 to 8210 - it does work tho.

 

https://www.windowscentral.com/disable-adaptive-contrast-surface-go

 

You will probably find you have to repeat this after any system or graphic driver updates, as the value is reset.

 

Hope this helps :)

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2 Posts

12-23-2019

US

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  • Message 4 of 18

Re: Yoga C940-14ILL - automatic brigthness issue and whitish screen after logging in

2019-12-23, 21:30 PM

The bright elements on the screen happen to me when switching from tablet to pc mode restart did not help but if I shutdown the laptop and turn it one the bright washed out color will go away 

 

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11 Posts

12-23-2019

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  • Message 5 of 18

Re: Yoga C940-14ILL - automatic brigthness issue and whitish screen after logging in

2019-12-25, 2:18 AM
I found that if I simply close and open the lid, whether it goes to sleep or simply turns off the display, when I open it back up, about 75% of the time the problem is solved. I have no clue what is causing this.
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16 Posts

12-19-2019

PL

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  • Message 6 of 18

Re: Yoga C940-14ILL - automatic brigthness issue and whitish screen after logging in

2019-12-25, 11:54 AM

Hi everyone,

 

After disabling adaptive contrast I don't have that dimming issue anymore, thanks! Quite ridiculous how far man must go to disable such basic thing...

 

Regarding screen turning white - in my case restarting Windows helps every time.  Next time the problem appears I will just try to close the lid and see what happens, thanks for the investigation. :) Hopefully this issue will be solved soon within next drivers update, as it doesn't seem to be a hardware problem.

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16 Posts

12-19-2019

PL

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  • Message 7 of 18

Re: Yoga C940-14ILL - automatic brigthness issue and whitish screen after logging in

2019-12-25, 17:06 PM

Great. This time only Explorer windows changed color, but now they look like they're greyed out instead of being super white. Locking or closing the lid does not help. Reboot did though.

 

About the dynamic contrast - changing the registry did not change anything in fact. Wmilun is probably right - the problem only exists when I have HDR video open. That setting is also greyed out in my Dolby control panel. Nevertheless, it's not annoying since I know how it works ;)

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2 Posts

12-10-2019

GB

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  • Message 8 of 18

Re: Yoga C940-14ILL - automatic brigthness issue and whitish screen after logging in

2019-12-29, 16:33 PM

Same issue here. A restart didn't fix it, I had to shutdown first :(

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2 Posts

01-01-2020

US

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  • Message 9 of 18

Re: Yoga C940-14ILL - automatic brigthness issue and whitish screen after logging in

2020-01-01, 16:23 PM

how did you disable it?

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2 Posts

01-01-2020

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  • Message 10 of 18

Re: Yoga C940-14ILL - automatic brigthness issue and whitish screen after logging in

2020-01-01, 16:25 PM
how did you disable it?
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