Laptop troubleshooting issue

[Panama Red]

This one has me puzzled. I have a customer with a 2 year old Dell Inspiron E1505. In early 2008, the monitor was replaced under warranty. I don't know if the inverter was changed too and neither does the owner. I've worked on this machine several times over the last year disinfecting it, replacing the battery, and replacing the ac adapter. At one point we added a bios password to keep her son from using it without permission. Now to the problem.

A couple of weeks ago she called to tell me the screen was black on boot up. The power light was on and the hdd light would flicker momentarily and then stop but nothing was displayed on the screen. First thing I did was pull the hdd and run a backup of her files. I put the hdd back in and the darn thing booted right to the bios password screen. I tried it several times over the next couple days and it always booted up. Thinking it was a loose connection, I returned it to her and it ran fine for a few days. Then, bingo! Black screen again. This time I tried to start it as soon as it was in my possession. Black screen for me too. I held a flash light up to the screen and saw nothing in the background which tells me the backlight isn't working. Now, backlights don't stop working and then start again on their own. Logically I figured the problem is a failed/failing inverter. I checked my used parts and had a used inverter that I assumed was good. Installed it and the pc booted right up. Put it all back together and tried several more times and it booted every time. She picked it up this am, got it home and (you guessed it!) black screen again! - and I got a phone call.

I'm still leaning toward an inverter issue but I have no way to test them. I can buy a new one off ebay for less than $10 so that's the current plan. The only other thing I can think of is a problem with the circuit feeding the inverter or a video chip issue. Anyone have any ideas they'd care to offer?

update: She just called agaiin and now it does show a faint image in the background so she entered her password and it booted to the user login screen. That screen was fully illuminated like normal. Then she logged into her user name and the screen went dark again with the desktop image visible in the background when using a flashlight. I had her power it down, unplug the adapter and remove the battery. Put it all back in and rebooted - black screen with no faint image - just black. Power off and power back on, screen faintly lighted until user login screen then it was bright again. Boot to desktop and no backlight. I love troubleshooting intermittent issues!

[Spools]

Any chance it has something to do with the power management in the BIOS?

[Panama Red]

Originally Posted by Spools Any chance it has something to do with the power management in the BIOS?

I wouldn't think so. Seems like it would do the same thing every time if that was controlling the video. But it's worth another look in the bios. Thanx for the idea.

[Masaki 7-11]

It might be an issue with the BIOS, a BIOS update might help.

[rjfvillarosa]

PR.
That sounds like a power issue, if it's easy enough to access it, try putting a multimeter on the points where the AC jack connects to the motherboard.
Do you remember the one I had here with the very thin black line down one side of the screen that slowly broadened out until it looked like a one inch wide bar-code running the full height of the screen?
That turned out to be a bad cable from the brick to the AC jack.

[Panama Red]

Originally Posted by rjfvillarosa That sounds like a power issue......

Looks like you may have nailed it. She messed with it a bit over the weekend and discovered that it works fine as long as the ac adapter isn't plugged in. When the battery runs down, she plugs the adapter back in and lets it recharge. It sits in a kitchen alcove and doesn't get used as a portable so she's fine with using it this way for now. May try a different adapter and see if that makes any difference. Otherwise, she's talking about just buying a new laptop.