Laptop screen blank

[gingerwinger]

Hi All

I have a laptop that the screen is blank with no image at all. I plug in a monitor and I get the picture as normal so what could the problem be? Is it the inverter as I have read this just seems to fade in time. There was no fading just straight to blank.

Any help would be appreciated.

Regards

[rmrd]

Shine a flashlight onto the screen while it's doing this. Do you see a faint image?

[gingerwinger]

Hi

Thanks for the reply :-)

Yes there is a faint image but not even the led's on the inverter are working. Does this mean is dead? Is there a way to test the inverter is getting power to it?

[rmrd]

If you have a second laptop that has an inverter with the same connectors, you can switch them out.

Otherwise, just assume it's a bad inverter and pick up a new one on eBay for 15-45 dollars. It's the easiest part of the LCD assembly to switch out.

[gingerwinger]

Thanks for your help. I have found one off ebay which didn't work but now ordered another so hopefully it will work this time!

Is this a typical sign of a dodgy inverter?

I really appreciate your help :-)

[rmrd]

Thanks for your help. I have found one off ebay which didn't work but now ordered another so hopefully it will work this time!

Is this a typical sign of a dodgy inverter?

I really appreciate your help :-)

If your next inverter doesn't work either, it could be that your backlight has gone out.

[gingerwinger]

I have just done a multimeter test on the main capacitor thingy on the inverter and it has four solder joints on one side and two the other. When I use all four against one of the solder joint on the two side it all works but when I use the other on the tow side it get no reading from any of the four on the other side of the thingy! Does this mean its bust?

All other thingys on the board get a current through them. I hope you understand what I mean by thingy!!! :-)

[rmrd]

Without a picture of the thingy, I have no idea.

There seem to be lots of thingies on inverters.

If the new one produces the same result, it's the backlight.

[RueB2sDe]

It may be under your video controllers under control panel that the manufactur has placed a firm ware. I know with eMachines and Gateway laptops there is a setting in Control panel that allows you to disable the LED on laptop for an external monitor. Try booting to safe mode to see if you get a LED picture if so go through your Video settings.

[rmrd]

Highly doubt that's the case Rue, that's something that's kind of hard to "accidentally" do. Also, the monitor in that case typically doesn't just turn off the backlight (which is a CCFL tube, not an LED), it turns off all video. There wouldn't be a faint image.

[RueB2sDe]

It might also be that the Enable VGA mode might need to be chosen upon starting up while tapping F8. I always say try the software setting first before buying new hardware.
If worse comes to worse try plugging in someones monitor or your monitor to another computer to see if they work.

[gingerwinger]

Hi

I have just installed the 2nd inverter I bought off ebay and still it doesn't work!!!! I'm trying to get to the LCD bulb but can't find it! Is it possible that my bulb is a sheet of white behind the glass which lights up or is there a simple bulb to find? Is there a way of testing if its working?

I really appreciate all your comments, they're a great help :-)

[rmrd]

Hi

I have just installed the 2nd inverter I bought off ebay and still it doesn't work!!!! I'm trying to get to the LCD bulb but can't find it! Is it possible that my bulb is a sheet of white behind the glass which lights up or is there a simple bulb to find? Is there a way of testing if its working?

I really appreciate all your comments, they're a great help :-)

Whoa now, hang on there.

Don't go ripping up the back of your LCD assembly to find the backlight if you don't know what you're doing.

The CCFL tube is usually located down near the bottom of the LCD assembly, behind a screwed-on metal shielding. You can typically trace the connection that goes into the inverter (pink wire + white wire) to verify this.

Honestly, I don't recommend you doing it yourself. I do backlights once or twice a week and sometimes still break one or two new ones (they're very fragile) before getting everything perfect. You could end up with a lot of backlight bleeding on the screen or even ruin the assembly itself.

If you do decide to go through with it, you'll need to order a new bulb (I use lcdpart.com) and get out your soldering iron -- the tips of the pink and white wires are touch soldered to the tips of the backlight bulbs. You might also invest in some heat-shrink tubing from radioshack to make sure there won't be any grounding/sparking/whatever issues after the install.

To answer your original question though, the white sheet is not the bulb, that's part of the LCD assembly. You'll know it when you see it, it's like a very skinny mini-version of those long bulbs they use in highschool ceilings.

http://site.ccfldirect.com/33

[gingerwinger]

I thought it must be like that but couldn't find it, I didn't go looking too hard mind! :-)

The reasoning behind all this problem is as follows:

This is an old laptop that I am doing up for my daughter as previously the cables split from opening and closing the laptop plus the hard drive broke. I found new cables and drive and replaced them. Unfortunately on replacing the cables the screwdriver touched the motherboard and a spark happened and the motherboard never worked again! Prior to this the screen was white and no image so I was told it could be a loose connection hence the screwdriver! Now I have a new board and the screen doesn't work so I thought I may have damaged the inverter during the screwdriver incident! Nothing! and still nothing. Could the screwdriver problem have broken the bulb? I have tested the new board on another monitor and I got the bios screen. Its nothing I need to do in the bios is there to make it light up?

This is a right mess but hopefully I'll get there :-)

[rmrd]

I thought it must be like that but couldn't find it, I didn't go looking too hard mind! :-)

The reasoning behind all this problem is as follows:

This is an old laptop that I am doing up for my daughter as previously the cables split from opening and closing the laptop plus the hard drive broke. I found new cables and drive and replaced them. Unfortunately on replacing the cables the screwdriver touched the motherboard and a spark happened and the motherboard never worked again! Prior to this the screen was white and no image so I was told it could be a loose connection hence the screwdriver! Now I have a new board and the screen doesn't work so I thought I may have damaged the inverter during the screwdriver incident! Nothing! and still nothing. Could the screwdriver problem have broken the bulb? I have tested the new board on another monitor and I got the bios screen. Its nothing I need to do in the bios is there to make it light up?

This is a right mess but hopefully I'll get there :-)

Sounds like it's time for a new laptop. :P

I've had the cable-split problem before on an old Toshiba, and after replacing the cables, I got nothing but backlight.. Turns out that I didn't secure the cable well enough on the back of the LCD assembly.

Right now, everything you're saying is pointing to an issue with the backlight. Faint image, new inverter doesn't work, board works fine on another monitor, etc.

If you don't trust yourself to repair the backlight -- it is a very tedious and delicate process -- some local computer shops will.

.. Some. A lot of them won't touch laptop internals outside of RAM and the HD.

[gingerwinger]

I've got the backlight bulb out which wasn't too much of a problem so will aim to find another to replace it. God only knows how something that delicate will make it through our postal system!!!

I may as well go for it as its no use to me like it is and to be honest I love the challenge. Now got to find a bulb now!

Thanks so much for all your help, you have been a great help for which I'm greatfull.

Cheers