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5 Posts

09-30-2020

Russian Federation

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Lenovo yoga c940-14iil SCREEN BUG

2020-09-30, 9:06 AM

Hello

I have screen bug on my lenovo yoga c940-14iil (look at the video by link below)

 

https://cloud.gaponyuk.com/index.php/s/dyMeaRBUYXUFgoq

 

 

Time after time appear lines on screen. Is it known issue? Is it possible that it is software/driver issue?

 

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2836 Posts

03-11-2020

Greece

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Re:Lenovo yoga c940-14iil SCREEN BUG

2020-09-30, 9:47 AM

Hi DenisVG

 

My first guess would be that it is driver related.

 

So I'd suggest trying to uninstall display devices with drivers and reinstall:

- Press the Windows key + X and select "Device Manager"

- Expand "Display Adapters"

- Right click the AMD, NVIDIA and/or INTEL VGA devices and select "Uninstall"

- If prompted to uninstall drivers associated with the device, tick the box and continue.

- Perform a restart of the laptop. 

- You can download the newest drivers for your display devices on the Support Page

- Plot in your serial number, then head to Drivers & Software, then Video & Graphics Drivers.

 

Test

If this does not help the issue, then I'd try to connect an external monitor to see if the issue is present there as well. 

 

Possible outcome 1:

If it is then we might be looking at a Windows update that has messed with some drivers somewhere, and hunting these drivers down is usually a witch hunt or we are looking at a faulty graphics device, and most likely the discrete one as that is what the external monitor will be utilizing.

 

Possible outcome 2:

In the event there is no problems on the external monitor, then we might be looking at problems with the integrated display adapter and/or the in-buildt LCD screen.

 

I'd begin with checking if it might be Windows Updates causing the problem, to rule it out completely.

 

Rolling back to a previous Win 10 Version :

- Open the Windows 10 Settings Menu by clicking the gear icon in the Windows Start menu, or by pressing “Windows+ I” keys.

- Click “Update & security”

- Click the “Recovery” tab on the sidebar.

- Under “Go back to the previous version of Windows 10,” click “Get started.”

- After some elapsed time after last update(10+ days), this option is often not available. Please continue below.

 

- There should always be a "restore point" you can choose from "System Recovery"

- Click the Windows key and type "System Recovery" and click "Recovery" in the list.  

- Select "Open System Restore" - Click "Next" and select the latest "Restore point" where the device was working.

**Note: System Restore Points will only remove Apps and Programs installed after the selected Restore Point date. It will not remove word/text files or pictures etc.

 

 

Disable Automatic Hardware drivers update

- Right click the Windows Icon, select the "Search" Function.

- Type "Control Panel" and select "Small icons" or "Large Icons" in the "View By" top right.

- Click the "System Icon"

- Navigate to "Advanced System Settings" -> "Hardware"

- Click "Device Installation Settings" and Select "No"

**This will prevent Windows from interfering with your hardware drivers in future updates, but keep crucial security updates rolling.

 

If things do not look better after having tried these, then we are most likely looking at a hardware issue.

To rule out a software/driver issue all together, I'd recommend the following:

 

OKR - One Key Recovery 

**This is a complete factory reset of the computer

**Loss of data can occur, so we advise you to backup your data if possible.

 

- Completely shut down the device.  

- Press the Novo Button :  It is the small reset hole on most devices that you need a unfolded paperclip to reach.  

- In case you do not own a device with a OKR button. You can also find out where it is or what reset function it is for your device at the support page under.

 

Knowledge Base & Guides -> User Guides -> And clicking the User guide(Not HTML one) in the list -> Ctrl+F to search the document for "Reset" and/or "Novo Button" / "Novo Hole"

 

- When the system boots up, a menu will appear, select System recovery and follow the recovery process.

- When entering the Windows environment again. Perform the "Disabling of Automatic Hardware driver updates" before allowing any Windows updates.

 

If the issue is still there after a factory reset, we can safely conclude that it is a hardware fault.  Depending on the results of the external monitor test as laid out above.

 

Regards

 

Voithos

 

 



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5 Posts

09-30-2020

Russian Federation

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Re:Lenovo yoga c940-14iil SCREEN BUG

2020-09-30, 12:25 PM
Hi Voithos, Thanks for your reply. I reinstalled the INTEL GFX driver from support page. I hope the bug will not appear (as I mentioned before, the bug appears from time to time). I will test it for a couple of days.
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18 Posts

10-04-2020

United Kingdom of Great Britain and Northern Ireland

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  • Message 4 of 20

Re:Lenovo yoga c940-14iil SCREEN BUG

2020-10-04, 7:59 AM

I'm afraid faffing with the display drivers will not help this issue (and I suspect Lenovo know this).

 

First of all, it is not just you - the internet is full of people who are having this problem.

 

On Reddit, we have pretty much narrowed this down to an issue with the C940 and the latest build of Windows. More specifically, we are fairly sure that the issue was introduced in the specific Windows 10 build 2009 patch KB4566782:

 

https://www.reddit.com/r/Lenovo/comments/irj6zo/is_anyone_else_having_this_issue_on_their/

 

Reverting to Windows 10 build 1909 will resolve it, but this is a non-trivial fix if you upgraded Windows 10 more than 10 days ago. However, if you are still within the 10 day downgrade period, it is worth reverting (and I can confirm, having done so, this will resolve the issue).

 

There is clearly an incompatibility with changes that Microsoft made in later builds/patches in Windows with either the Lenovo/Intel graphics drivers, the C940 as a whole or all three. Lenovo, as I said, must surely know this by know because too many people are having this issue in the wild. As such, it is disappointing that they are telling people to engage in pointless messing around with drivers which will have no effect on the issue.

 

A true fix - i.e. being able to run the latest builds of Windows without screen glitching - will not come until either Lenovo, Intel or Microsoft resolve the specific issue.

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5 Posts

09-30-2020

Russian Federation

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  • Message 5 of 20

Re:Lenovo yoga c940-14iil SCREEN BUG

2020-10-09, 9:49 AM

Yes, I already know about it. I reinstalled all the drivers, but the bug is still with me ...

It's sad to hear that Lenovo knows about the bug and doesn't do anything with it.

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170 Posts

04-26-2020

United Kingdom of Great Britain and Northern Ireland

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  • Message 6 of 20

Re:Lenovo yoga c940-14iil SCREEN BUG

2020-10-09, 17:15 PM

It's not sad it's quite normal.

 

Lenovo continually release machines full of bugs and never ever fix anything.

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10 Posts

10-07-2020

Pakistan

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  • Message 7 of 20

Re:Lenovo yoga c940-14iil SCREEN BUG

2020-10-11, 19:23 PM

I am very disappointed with lenovo. i never faced such problems with HP . buying lenovo was a very bad decision considering they dont care.

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10 Posts

10-07-2020

Pakistan

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  • Message 8 of 20

Re:Lenovo yoga c940-14iil SCREEN BUG

2020-10-12, 15:32 PM

Ok , i did a full factory reset, then disabled windows update and 20 minutes later, it happened again. first its these horizontal bars occasionally and then later on flickering also starts. . I haven't been able to do my work for the past three weeks. LENOVO ..... Help. i am sure its the bios now.

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2 Posts

10-13-2020

United Kingdom of Great Britain and Northern Ireland

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  • Message 9 of 20

Re:Lenovo yoga c940-14iil SCREEN BUG

2020-10-13, 14:10 PM

I've also been experiencing this problem since I purchase my laptop a few weeks ago.  Tried all of the recommended fixes and nothing worked.  However, yesterday afternoon I was alerted to a new Windows update and I've not experienced the problem today.  I'm about to return this laptop but if it's ok now, I'm happy to keep it.  I don't want to tell Lenovo all is ok prematurely, however.  Has anyone else experiencing this problem had success with the new update?

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2 Posts

10-13-2020

United Kingdom of Great Britain and Northern Ireland

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  • Message 10 of 20

Re:Lenovo yoga c940-14iil SCREEN BUG

2020-10-13, 15:43 PM
Forget that - it's just done it again
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