# Dell Inspirion 6400 Blank LCD Screen



## van12345 (May 6, 2008)

Hello,

I have a Dell Inspiron 6400 and just recently I turned the laptop on and it will boot up however the screen remains blank. I know for a fact that it will boot up because when I plug in an external monitor everything works fine except for the LCD monitor. I ran it in diagnostic mode by pressing the <fn> key and then the powder button. The screen turned blue and the following results appeared.

MATS Test - Pass
March B Test - Pass
MCMch Test - Pass
MCMATS Test - Pass
Incompatible video controller
Vesa function 0x4f02 returned AX = 34f

I am really stumped. If anyone could help me out I would appreciate it.
Thank You


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## TriggerFinger (Jan 30, 2008)

hi,

put a light near the LCD and look if you can see the desktop. if so, it could be the inverter or the backlight. if you do not see anything at all, it could be the LCD assembly.


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## van12345 (May 6, 2008)

I didn't see anything when I did that. 

but I do not think that it is the LCD assembly because when I boot it up without an external monitor attached to it, I see a few words like it is trying to boot up and right before you get to the main windows account window the screen goes blank.

So I think the monitor is fine because I can see stuff while it is trying to boot. I wonder if it is just the driver for the video card or there is something wrong with the system file structure.

Do you think that a reformat would fix it?


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## TriggerFinger (Jan 30, 2008)

yup you are correct. if you see it do POST or at least get into BIOS settings, then it is NOT the LCD. it could be anything but the LCD.

if it is the video card failing, then you would not see anything even on the external monitor. however this is not the case. and like you said you see POST on the LCD but just blacks out just before Windows starts. 

try booting a live CD (XP live CD or linux live CD like Knoppix or PCLinuxOS). if you have an XP live CD created by BART PE, boot from it. if it runs well with the LCD it could mean the drivers. if possible set resolution in the display properties to the highest possible supported values and see if the video card can handle it.

another way is to enter Safe Mode if you still can (tap F8 as it boots). if this works with your LCD, it could be the drivers.

if it runs with a live CD but fails in Safe Mode, try CHKDSK /R using XP install CD. you can also check your hard drive health using a hard drive diagnostic tool. d/load a diagnostic utility for the brand of HDD that you are using (see HDD diagnostic tools link on my sig).


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## alptrans (Jul 28, 2008)

Did you get anywhere? Sort out your problem?
Interested to know as I am encountering the same problem. Reinstalling drivers does not help.

Tx


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## van12345 (May 6, 2008)

I really didn't get anywhere with my problem. I was on the phone with Dell Hardware support and they said that it was a bad LCD monitor. So right now I am trying to save up some money to get it replaced.

I did try the reformat, but I recieved the same results as before.


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## TriggerFinger (Jan 30, 2008)

Did you try my suggestion to use linux live CD?


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## alptrans (Jul 28, 2008)

Very interesting. Mine loads Windows XP - I can hear the Welcome tune of it. 
When starting, the screen of my laptop comes up with the www.dell.com written in white on blue background at the top of the screen on one line and on the top right I have the F2 and F12 key message displayed. And as you I have the blue screen with the same error message coming up when pressing down the Fn key. So I am surprised at the answer of Dell as the monitor displays something in the middle in blue background as you describe - so if the LCD is off how comes that it can display in the middle something it is not supposed to?:4-dontkno Puzzles somehow! I tried an external monitor and it works perfectly fine indeed. I am about to try a Bios upgrade as I have found that mine is version A10 and latest is A17 with a critical update in A14. Let see what will happen!


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## jlwoody04 (Jul 31, 2008)

My wifes laptop has the exact same problem as you describe. I spent a bunch of time online with dell tech support, they finally came to the conclusion it was either the LCD or the mother board. They wanted $200 to look at it and if it was the mother board another $300. So I had them ship me a display for $200, which they said I could return if it didn't fix the problem. I installed the new display tonight and same problem. 

So I would be interested if you have found any other information. Just a side note. If I run the diagnostics by holding the function key and power key with a external monitor I don't get the error message about incompatible display. I only get it when I run diagnostics on LCD. Not sure if you see the same problem.


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## van12345 (May 6, 2008)

I tried to use the Knoppix CD but that didn't work. I am not sure if that is the same as your Linix Live CD. 

If not do you know where I can get one?

Thx


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## TriggerFinger (Jan 30, 2008)

When you say it did not work, you mean it did not boot? I assume you copied directly the ISO file into the blank CD. If so, follow these steps:

1. Get/Download Knoppix ISO file
2. Get/Download CD burning tool (ex. ImgBurn)
3. Install CD burning tool (ex. ImgBurn)
4. Right-Click on Knoppix ISO file and select 'Burn with ImgBurn'.
5. Make sure you have a blank CD in your CD/DVD drive.

Leave the CD in your CD/DVD drive and power OFF then power ON the laptop. Make sure you boot from the CD/DVD drive. You may have to make changes in boot order in BIOS settings to be able to do this.


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## Houndog777 (May 17, 2007)

http://www.frozentech.com/content/livecd.php


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## alptrans (Jul 28, 2008)

to jlwoody04: yes I get the same problem. I have even been able to get the screen proposing me the choice of the different startup modes of Windows XP since changing the BIOS. I will be starting reinstalling the machine sometimes today after complete reformat. 

To TriggerFinger & Houndog777: thanks for the info but it means changing from Windows to Linux . in my case I cannot do it at least not on that computer.

I will keep posting.


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## TriggerFinger (Jan 30, 2008)

alptrans said:


> to jlwoody04: yes I get the same problem. I have even been able to get the screen proposing me the choice of the different startup modes of Windows XP since changing the BIOS. I will be starting reinstalling the machine sometimes today after complete reformat.
> 
> To TriggerFinger & Houndog777: thanks for the info but it means changing from Windows to Linux . in my case I cannot do it at least not on that computer. -- it is in LIVE CD. That means you NEED NOT INSTALL anything on your hard drive as it runs from your CD drive. Here's a link for more details.
> 
> I will keep posting.


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## alptrans (Jul 28, 2008)

Thanks for the info - I downloaded the Knoppix and burn a CD. The CD start perfectly well when the laptop is connected to an external monitor. When started on its own LCD display, it starts but nothing is visible even when pressing keys like F2 or F3 to get further explanations on Knoppix.

At this stage I have not reformatted the drive and following the experience with this bootable CD, it appears to me that the VGA chip on the motherboard has gone faulty - purely and simply. I have never a case of this nature - usually the LCD goes completely black in one area at least if not in totality!

So the only thing left is - if not replacing the laptop - to change the motherboard as the VGA chipset cannot be unmounted and replaced - quite an expensive operation. I do not believe a simple moment that the LCD in itself is faulty at all.


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## TriggerFinger (Jan 30, 2008)

OK... with Knoppix booting up successfully, check the LCD if you can still see beyond the dark screen. Put a flashlight at an angle near the LCD. If you can see the Knoppix desktop then it could be your backlight or the inverter. Another scenario is if you cannot see anything beyond the dark screen, it could mean you need a new LCD. 

Post back which scenario describes yours the best.


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## alptrans (Jul 28, 2008)

I do not think that the LCD is off. THe test from the diagnostics do display perfectly well. Also during boot up hitting the F8 key provides me with the Windows startup screen (Start normally, in Safe Mode,... etc.). If the LCD was off, I would not get these - am I wrong ?


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## TriggerFinger (Jan 30, 2008)

So you mean you get something on the LCD when using Windows (i.e. Safe Mode) but nothing in Knoppix? If it is intermittent, it could still be the LCD.

Given the above case you could suspect your video card or an intermittent malfunctioning LCD. Given the two, I would go with the LCD first. Replacing the video card would also mean replacing the mobo.

EDIT:
This is very difficult to pin down unless you have the extra parts to use (i.e. a spare working LCD or a spare working mobo).


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## alptrans (Jul 28, 2008)

I just got off the phone with Dell support - believe or not I spent nearly 72 min with them. I had to access the connector of the LCD at the base of the keyboard - so unscrewing everything whilst on the call. Nothing worked of course. The computer being just out of warranty and due to the time and the confusion the technical support seems to be in, they will repair the laptop under the warranty as a gesture for the time spent over the phone going nowhere! Not bad for a result. I will keep you as informed as I can of what they will have discovered. The collection will happen next Tuesday - return is TBD


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## alptrans (Jul 28, 2008)

I would agree with you the the VGA chipset if malfunctioning i.e. allowing the text to come though but not the graphics.


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## TriggerFinger (Jan 30, 2008)

That is good news. Will the parts be covered just in case some will need replacement?

Do post back what they find out. Cheers.


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## jlwoody04 (Jul 31, 2008)

alptrans I will be very interested in finding out what dell finds with your laptop. I have the identical symptoms as you do. I did replace the LCD and it did not fix my problem, so I am convinced this is the video controller. 

Keep us posted please.


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## van12345 (May 6, 2008)

TriggerFinger,

I did exactly what you said, downloading a copy of Linux and I recieved the same result.

I recieved an error saying "Unknown keyword in config file" Then the computer LCD went blank.

Alptrans, 

If Dell fixes your computer can you tell me exactly what they fixed to correct the problem? I would really appricate it.

I am still stuck

I think that it is funny that this computer broke a few months after the warrenty was up.


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## TriggerFinger (Jan 30, 2008)

van12345 said:


> TriggerFinger,
> 
> I did exactly what you said, downloading a copy of Linux and I recieved the same result.
> 
> ...


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## alptrans (Jul 28, 2008)

Promise to everyone, I will let you know as much information as I can get from Dell. At this stage I still believe that the VGA chip is faulty, in essence it means replacement of the motherboard as you cannot buy it and replace it alone (as far as I know).

You will have to bare with me for probably a week if not more. Collection is next Tuesday and I will probably not get the laptop back for another week after that.


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## Zolafan (Aug 13, 2008)

I had a similar problem with an Inspiron 6000. Completely black LCD screen but worked fine on an external monitor, eventually narrowed it down to a faulty magnetic lid switch. A sharp tap on the front left side of the palm rest beside the touch-pad would bring it back on, but each time i closed the screen down and then reopened it the same problem occurred! Still trying to source a replacement part, considering removing the magnet from the screen casing in the mean time.


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## alptrans (Jul 28, 2008)

I have now received the laptop back. The information I have gathered is the VGA card faulty has been replaced. I believe in this case tha the motherboard might have been completely changed.

Best regards.


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## van12345 (May 6, 2008)

So it was the motherboard and not the monitor? Do you happen to know how much it cost to fix?

Thx


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## TriggerFinger (Jan 30, 2008)

van12345 said:


> So it was the motherboard and not the monitor? Do you happen to know how much it cost to fix?
> 
> Thx


I think DELL covered everything.. as per *alptrans* post previously


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## alptrans (Jul 28, 2008)

Unfortunately I cannot tell you anything regarding price. All I can tell is that Dell organise the pickup by special collection and delivery. The collection guy came with a special cardboard box specifically designed for a laptop! It came back in the same box.
As explained, they must have replaced the motherboard. Definitely not the LCD monitor.

Best


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## van12345 (May 6, 2008)

I just got my Laptop back. It took me a while to be able to send it in because of the money. The problem ended up being a bad inverter. So I sent it into the Dell Repair shop and since my warrenty was up it ended up costing me $238 to fix that. I am sure it was an easy job to do if you know what you are doing. I probably got ripped off.

So I had to backup all my data and send it in, and when I got it back, the files on my hard drive got corrupted some how. So I spent another 45 min reformating.

Anyway that was the problem. Just FYI for future readers.

Thanks for your help


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## TriggerFinger (Jan 30, 2008)

We have suspected that at first but you said there is nothing beyond the dark screen (screen totally dark, no images even with a flashlight or viewed at an angle)... anyways.. thanks for the update and I am happy to know you got it working.


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