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Display turns off when laptop is opened beyond 90 degrees (approx)

When I open my laptop's lid beyond a point (say approx 90 degrees), the display turns off while the programs are still running.

This problem initially started at more than 120 degrees (which was not affecting me much). But it deteriorated gradually to around 90 degrees now.

The problem is consistent (happens at any time of the day and usage).

Currently using the laptop by not opening it beyond 90 degrees and adjusting my seat. No other problems exist. Works fine if I use it this way. But it's getting frustrating and soon it will deteriorate further to <45 degrees making it unusable.

It's definitely a HARDWARE issue related to the screen.

I live in India. This is a Lenovo B490 laptop.

Can somebody please point out which part is malfunctioning and what to do about it?

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Hi @bachuz ,

Check with a torch, held at an angle close to the screen whether you can still detect an image at all when the display "turns off". If it is there it will very faint, so you might have to try this in a darkened room to see if you can detect any images at all. It may be that only the LCD backlighting is missing and not the video signal.

If you cannot detect anything at all or even if you can detect an image, I suspect that it may be that the video cable is the problem (where it passes through, near the hinge, from the motherboard in the lower case to the LCD screen in the lid).

Here is a link to the service manual for your laptop.

Scroll to p.73 to view the necessary pre-requisite steps and then the procedure to remove the LCD cable from the display unit.

Here is a link to just one supplier of the replacement part. It is not a recommendation to use them. It is shown to give an idea of the cost of the part. There are others online who may suit you better. Just search for Lenovo B490 LCD cable part for results.

Hopefully this is of some help

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Thanks a ton! As you said, I can faintly see images on my screen with a torchlight. I guess the only solution is to replace the cable then?

Any chance I can screw up stuff while replacing it myself?


Hi @bachuz ,

It may be that the backlight section of the cable is not connected properly into the LCD screen and that is why movement might cause it to break the connection, but you won't know this until you can see how it is actually connected.

Before you start do a backup of your data and perhaps a system image as well as a safeguard.

By doing this nothing should go wrong, (it only happens when there is a possibility of you losing your data because you haven't backed it up). ;-)

If you take your time and follow the service manual procedures you should have no problems. (you'll also have to find out from the manual how to access the motherboard so that you can disconnect the video cable from the motherboard)

Keep containers handy to put the screws in as you take them out, make a note of any that are different or longer etc and where they belong.

If you find out that things aren't going as you thought, STOP, think it through, take a break then come back and start again.

Remember that with electronics, brute force is not necessary. When you come to remove cables from the connectors check them out first , do they have a bar that has to be flipped up or unlatched in some way so that the cable can be gently removed from the connector. Do not just pull them out you may end up pulling the connector off the board which is definitely hard to fix.

I'm not trying to scare you. I'm sure that you'll have no problems. Again, just take it steady and you'll be fine.

Good luck.


I'll give it a try, thanks!


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