Dell Inspiron 5720 LCD not working on windows 10

[CJ RB]

I have updated my laptop from windows 7 to 10. Everything was working good. Usually I connect my laptop to the external monitor. Few days ago I needed to use LCD on the laptop but it would load into black screen. When I connect to the monitor I see the booting and it works. As soon as disconnect from the monitor it is black. So I shut it down and boot it up few time but I don't see any booting information.

Here what I did to debug:
1. Reinstalled and updated graphics driver (Intel HD Graphics 4000). When un-installed the driver, couldn't even connect to the monitor. Blindly somehow got into the safe mode and from there installed driver back.

2. Checked bios settings. No settings for video there.

3. Updated all divers (bios, chipset etc). Nothing changed.

4. I thought maybe there is a problem with the LCD. So I ran built in LCD test and it showed Red Green Blue and White colours. I didn't see any text or any other information on the screen though. Laptop was making beeping noises. So I'm not sure if it is good or bad.

I tried different options with (windows + P) to see if the monitors will change. Nothing there also.

When laptop boots up the black screen lights up sort of lighter black colour. I don't know whether there is a problem with windows 10 when it did one of its overnight updates or the problem with LCD or graphic card.

Any ideas would be much appreciated.
Thanks

 

[Trouble]

I was hoping that someone with an actual dell laptop might have an answer for you, but....
Does your laptop have a "Fn" key associated along the top row on your keyboard, that supports switch from the integrated display to an external display. Most of the laptops I have had, involved holding the Fn key on the bottom left while simultaneously striking the corresponding key (square icon approximating a monitor). As well as an Fn key combination to adjust screen brightness.

 

[davehc]

I run , and have facilities, to several Dell computers/laptops. I must say I have not experienced that problem. But, just to clarify, if you disconnect the external monitor, whilst the computer is running, do you then get the black screen, or is it only on boot up (without the ext attached)? In either case,, can you see the (white) mouse cursor?
Presumably you have tried the monitor settings - Quick way:
right click the desktop in the external (which you can work with, of course, select "display"). In the "Multiple display " block, I have mine all set to "Show only on 2". This defaults to a default. If I unplug my ext, under any circumstances, the picture reverts to the laptop.

You can also try turning off the fast start up (if it is on?) in the power options. This seems to work for many, in all brands of computer with screen problems.

 

[CJ RB]

On the keyboard there is a switching display button. I used it before. It doesn't work. If I disconnect the monitor it just stays black. No mouse, no booting logo etc. When I performed the LCD test at the beginning the it was black, then the colour of LCD was changing from blue, red, green and white and after that it was just beeping 3 long beeps 3 times and 3 fast beeps. My brother has the same laptop and when he performed the test he gets different images. He gets vertical and horizontal colour bars.

So I'm not sure if it is a graphics card because my external monitor works or it is LCD display but it was displaying some colours so it kinda tells me that it is working.

I'll try turning off fast start up and see if it works.

 

[Trouble]

IF you are using the VGA port to attach an external monitor and that external monitor seems to work OK, then I would suspect that the same GPU (Video Card) drives both the external port connection as well as the integrated internal display, so I don't thing that it would be a problem with the GPU unless perhaps some settings change that you have made regarding resolution or Hz is more than the internal display will tolerate.

 

[CJ RB]

IF you are using the VGA port to attach an external monitor and that external monitor seems to work OK, then I would suspect that the same GPU (Video Card) drives both the external port connection as well as the integrated internal display, so I don't thing that it would be a problem with the GPU unless perhaps some settings change that you have made regarding resolution or Hz is more than the internal display will tolerate.

I'm using HDMI for external input. I agree with you, it can't be GPU as it is working. On Dell support forum they suggested to check LCD connectors on motherboard. I was hoping that it would be just a driver. I'll disassemble laptop over the weekend that will check the connectors. I'll post an update.

 

[davehc]

The beeping signal you are getting indicates a Ram problem. That doesn't seem to correspond with the fact that you do get a picture on the ext though.