Black screen problem

i have a dell laptop inspiron 8600c 15"4 screen, bought in 04/01/2005, with an ATI radeon turbo 9600 graphic card, centrino 1,7 processor, 1 gb ram.
suddenly the screen turned black i thought it went to standy mode,but it wasnt ... i restarted the pc to discover that it still black, but it's not really black because if i look closely with some light i can see that the pc work normally. i tried to connect it to normal screen, the pc worked normally.
i want to add that since few time, the color was becoming a bit red, but i thought it's not a big deal and i don't know if it's related to my last problem.
The only problem also i got 2 months ago, was that the laptop was going suddenly to standby mode, i cleaned it with spray and i launched the dell diagnostic tools, the problem was solved.

i looked in the net they say it could come from motherboard or inverter or a third thing called LCD backlight...can anyone tell me from what comes my problem ? or how can i know from which of these 3 reasons it's coming ?

thanks in advance for your help.

typically the problems like this would stem from the LCD backlight or inverter, as you mentioned you are able to connect with a desktop monitor and use the laptop as normal.
Typically if the LCD inverter is damaged you screen simply wont get power, or in some cases the laptop itself may not even power on. The fact that you say you can see the pc working normally if you look with the right lighting conditions lends to the probability that the screen and power source (the inverter) are working fine.
Also if it was a problem with the motherboard or graphics card, you would have stability problems even when you attach a desktop monitor to your laptop. You say when you used a normal monitor it worked fine, so that points to these components probably being fine.

The LCD backlight is basically a light source found behind the liquid crystal, allowing light to shine through the colored pixels. If this light source is damaged in some way, it would prevent it from lighting the screen, leading do what you described above.

Typically replacing the LCD backlight in laptops is somewhat complicated. First you would have to find a replacement back light, which dell may be able to provide you with (assuming your unit is out of warranty, if it is in warranty, contact dell tech support before trying to replace the back light), once you have the replacement you have to take the screen apart. Usually there is a couple dozen various size screws, and several delicate ribbon cables. If any of these cables are damaged, you may be forced to buy a whole new screen. But once the screen is removed, you remove the metal structure plate from the back of the screen, and look for the long, white rod that is usually placed at the bottom of the screen. Sometimes you'll see what is known as a light screen that attaches to the back light. What this does is allow the light from the backlight to evenly spread over the light screen, providing you with an evenly lighted LCD screen, instead of a screen that is brighter at the bottom than it is at the top.

It is one of the more difficult DIY repairs you can do with a laptop, especially if you are a beginner to such tampering. It should also be noted that once you do this, any warranty you may have with Dell would be voided, so once again if you have a warranty, use it.

if you want to undertake the project we'd be happy to assist in any way we can, I'm certain that I am not the only one who has done this before

Thanks a lot for your answer.
I contacted Dell today, they just propose to change the whole screen wich is very costy for an old laptop ( 365 euros ) !!
I looked on ebay for inverters they are not so expensive comparing to a screen price, same for black lights...is there a way to know before i command on ebay if what i need is a blacklight tube or inverter ? do you know any tutorial to make such diagnostic ? or a tutorial that shows with pictures or video for dell inspiron 8600 c , how to change the black light ?i found one for inverter but still needs for black light and also i need any clue to know if it's the inverter or blacklight

Could it possibly be a ribbon cable problem to the screen? I've seen that sort of thing before through wear and tear.

thanks Python15 for your answer, can you tell me where is located this cable and how can i check it ? in case you have any pic or tutorial for this i will be thankfull

I'll see what I can dig up.

It is possible that it is the ribbon cable, but based on what he described I would bet that it is the backlight. If it was the ribbon cable or the inverter, he would likely have no life what so ever out of the screen, but as he described it, he can see the screen is working, just has no light to make it readable.

The exact procedure for replacing an inverter or backlight (or even getting to the ribbon cables) will vary a bit from one laptop to another, but dell's service manual for the 8600 can be found here and will document most of the the removal process. I dont know what retailers in your area have access to the the backlight you need, but one place that I have purchased units from is midwest, but obviously you'll shop from what ever place available to you.

As for the specifics, you can refer to laptop repair 101 who have a great guide for replacing the backlight. Basic process involves carefully removing anything in your way till you get to the lamp, replace the lamp, and then put it all back together.

The hard part is really about taking your time. Do not rush something like this as a careless mistake could mean you have to buy a whole new screen as many of these parts may not be serviceable or easy to find. Take pictures if it helps, label/number the screws you remove so you know what order they go in, and basically just work in an area with no distractions, plenty of light, and make sure you have the tools you may need ahead of time.

thanks a lot for your complete reply Stang. I will keep this to the week end in wich i have the whole time, so that i don't rush things....I live in france, but i couldn't find someone that sell blacklights. I contacted dell, if they want to repair it, they change the whole screen which costs 365 euros !
I found some chineses stores that delivers such blacklight and they said they can send it to me to france, but i don't know if i can trust them.
I will check all this during the week end but in case you got any hint or additionnal help that you can offer i will be thankfull


Regards

Hi i have a similar problem with my 8600c. But on mine the screen works fine for about one minute and then the backlight goes off. Then i reeboot and the same thign happens again. Does anybody have any idea if this will be the backlight, graphics card or some sort of softwear problem?

thanks!

Here are some similar examples, maybe you can find some methods there (laptop screen turned black but laptop still running ):
ww.daniweb.com/forums/thread41145.html
(the link is not active, you need to put it in the browser, my account is new can't post link here.)