Dell 700m Backlight fails after 45sec

Hi. I have found a few related posts but I want to make sure I know what to replace before ordering parts. I have an Inspiron 700m and the display went out. An external monitor works. After reading some threads I discovered the display is actually working but the backlight is out. Except then it came back for a bit. I determined that it will work for about 45sec as soon as the notebook is opened (or I turn off the display by pushing the little button and then releasing it). It consistently does this - so I dont think there are any loose connections - perhaps an overheating issue or something is shorted and causing a runaway condition and protection circuitry is triggering.

I wanted to see if anyone has experienced this. I have read most people replace either the bulb or the inverter board. Obviously the bulk works - and I wouldnt think the issue would be there... a bulb is a bulb is a bulb. But there could be an issue on the inverter board. I dont know of any software issue that would cause this (except some really mean virus).

Thanks!!!
Jeremy

jeremy--
did you find a solution to your problem?? i have the same problem... i thought it was the inverter board too, so i swapped out the inverter board for a brand new one... nothing changed! same symptoms as before...
50 dollars later, i decided to see if it was a problem with the bulb... took apart the LCD and saw that one of the leads to the bulb was broken/poorly connected. also the bulb had a black band in it...
as of right now, i haven't gotten it working yet... i just ordered a new bulb so i'm going to try that... i'll let you know how it turns out... but next time i wouldn't be so hasty to blame the inverter...
btw... sometimes when my screen would die after the initial 45 seconds, i hear some kind of fizzing or static sound... did that ever happen to you?

Hey guys, sorry for the not so happy reply to any of your problems.

I just wanted to post and say that I have the exact same problems too. I'm planning on just replacing a new LCD screen for my sister. I'll be checking back. Hopefully something news is posted (crosses fingers).

Anywho, hopefully you guys have better luck. =)

Amazing. I found this thread as I was preparing to open my 700m to explore the problem... applied your "remove the battery trick", and everything seems hunky-dory... for now.

Any idea what's wrong?

My 700m also turns the backlight off after 45 seconds. It seems to be EXACTLY 45 seconds. I replaced the inverter board, no luck. External display works fine. The battery "trick" does not work for me.

I was wondering if you guys have been able to figure out the source of the problem. Just as for the previous posts, my display goes black after 45/50 seconds and I'm hearing a fizzing sound during the initial 20/30 seconds. I'd add that when the display initially lights up it goes reddish for a short while. I've already tried replacing the inverter board but that didn't help.

It seems to me the failure occurs when the OS is about to display bright content (read higher screen power consumption). If I switch from the default X display (I have Ubuntu running on my 700m) to one of the monochrome ttys, i'm able to get the display to light up again and to switch back to the X display (!!!) The only thing is that I can sense an extremely light flickering. This is a manipulation i've done while writing this post so I guess it might still end up going dark in about an hour or so, but that pretty much rules out any malfunctioning with the inverter board and/or the LCD display/bulb. Just as Vash suggested it could be related to the video card, but isn't it built-in in the motherboard ?