HP Laptop - Blank screen

Forums › Laptops and mobile computers › HP Laptop - Blank screen

Technofreak

6656 posts

Uber Geek
+1 received by user: 3474

Trusted

#208564 16-Feb-2017 21:59

The screen on My wife's HP 4540S has stopped working.

The laptop starts and runs OK, it will drive an external screen.

The laptop screen is not entirely dead as it changes from a dark screen (but one that shows the glow you see when the screen is blank when a computer is on) to completely black and back again like happens during the boot up process. There is never any graphics displayed.

I tried the trouble shooting suggested on the HP website but no luck.

Is it likely to the the screen, the cable or the GPU. I figure that since an external screen works OK, the GPU is probably OK.

Any help appreciated.

Thanks

Sony Xperia XA2 running Sailfish OS. https://sailfishos.org The true independent open source mobile OS
Samsung Galaxy Tab S6
Dell Inspiron 14z i5

Dynamic

4015 posts

Uber Geek
+1 received by user: 1850

ID Verified

Trusted

Lifetime subscriber

#1721578 16-Feb-2017 22:07

Hmmmm.... this model has an LED backlight, if I recall correctly. It would be unusual for this to fail, but it is a possibility. If you look carefully at the screen, possibly shining a torch light on the right angle, can you make out whether a picture is actually showing on the laptop's screen, just incredibly darkly? The individual pixels on the display itself do not give off any light, and require a separate light source which in this case is a strip of LEDs on the very edge of the glass display, hidden behind the plastic edge of the screen.

“Don't believe anything you read on the net. Except this. Well, including this, I suppose.” Douglas Adams

Technofreak

6656 posts

Uber Geek
+1 received by user: 3474

Trusted

#1721582 16-Feb-2017 22:14

It appears the backlight is working. If you leave the laptop alone the screen appears to be timing out. The screen goes completely dark then lightens up around the edges when the touchpad is touched. You can actually see light at the bezel edges.

Sony Xperia XA2 running Sailfish OS. https://sailfishos.org The true independent open source mobile OS
Samsung Galaxy Tab S6
Dell Inspiron 14z i5

Dynamic

4015 posts

Uber Geek
+1 received by user: 1850

ID Verified

Trusted

Lifetime subscriber

#1721609 16-Feb-2017 22:33

Hmmm... that suggests to me the display panel or its cabling is likely to be the faulty party.

Perhaps back up your data and send the machine to someone like these guys to fit a new panel. Ask them to test the new panel works before putting the laptop back together again, and if the new panel does not work, presumably the fault is more advanced and likely not worth repairing. They might charge you $50-$60 to do this if they don't end up selling you a panel.

http://www.trademe.co.nz/computers/laptops/other/auction-1259757211.htm

If you consider yourself pretty handy, and you can afford to 'lose' the laptop if you make a mistake and kill it completely somehow, perhaps just order a panel and have a crack at replacing it yourself.

https://youtu.be/H_QYVTNbZv0

Note that while I have replaced my own mobile phone and laptop screens myself, I do not do this commonly so others may have a different opinion.

“Don't believe anything you read on the net. Except this. Well, including this, I suppose.” Douglas Adams

Technofreak

6656 posts

Uber Geek
+1 received by user: 3474

Trusted

#1721952 17-Feb-2017 18:02

I see no problems changing the screen. It doesn't look any more difficult than what I've done in the past. I'd just want to be pretty sure it was the screen before shelling out for a replacement one.

I might disassemble the laptop and check the connector ribbon and the connectors and go from there.

Sony Xperia XA2 running Sailfish OS. https://sailfishos.org The true independent open source mobile OS
Samsung Galaxy Tab S6
Dell Inspiron 14z i5

MadEngineer

4591 posts

Uber Geek
+1 received by user: 2570

Trusted

#1721999 17-Feb-2017 20:32

Tried the keyboard combo to switch screens? Windows key + P if in windows or fn key plus respectively labelled F-key

You're not on Atlantis anymore, Duncan Idaho.

Technofreak

6656 posts

Uber Geek
+1 received by user: 3474

Trusted

#1722004 17-Feb-2017 20:51

MadEngineer: Tried the keyboard combo to switch screens? Windows key + P if in windows or fn key plus respectively labelled F-key

Yep, had tried that, but tried it again just now. The laptop screen doesn't work in either duplicate or extended modes. The external screen works OK.

Sony Xperia XA2 running Sailfish OS. https://sailfishos.org The true independent open source mobile OS
Samsung Galaxy Tab S6
Dell Inspiron 14z i5

Mighty Ape

Shop now at Mighty Ape (affiliate link).

Technofreak

6656 posts

Uber Geek
+1 received by user: 3474

Trusted

#1722306 18-Feb-2017 16:23

Well, I disassembled the laptop enough to remove the screen. On this model that means pretty well pulling the whole thing apart. It wasn't that difficult with the aid of the service manual.

I also disassembled the screen assembly to the point I had just the screen on its own. I couldn't see anything obvious. I prodded and pushed on the cable plug at the rear of the screen and the area around this point.

I decided to put the laptop back together to the point I could run it. I left the screen bezel off along with anything else not absolutely needed. I wanted to see if the webcam etc was working.

Much to my surprise the screen worked. I shut it down and finished the reassembly process. It worked again when it was powered up afterwards.

I really don't know what I did to get it going. At this stage I'm assuming a poor connection on a plug.

I gave a One X One warranty on it and handed it back to my wife. This is my lowest warranty, (1 minute and 1 metre), as I don't know what fixed the problem.