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Dell 700m Backlight fails after 45sec

Last response: in Laptops & Notebooks
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February 19, 2008 2:35:49 PM

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
February 21, 2008 3:02:42 AM

It sounds like the inverter board to me to.
February 24, 2008 11:09:18 PM

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?
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February 26, 2008 2:37:39 AM

Ridgeback. Same as you - I just put in the inverter board and no love. I did have it working for ~1hr last week (with old board) - just randomly. Yes, I do hear the fizzing sometimes.

How did you get at the Backlight bulb itself? I took out the screen and I assume it is under the housing that is under the silver tape - but I didnt see a simple "low risk" way to get it out.

Fortunalty I found a board for only $25 shipped on ebay so I am not out that much (err, my sister is not out that much). Before having her pay $150 for LCD repair service I figure I will see how you do with a new bulb.

Jeremy
April 30, 2008 5:30:49 AM

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. =)
Anonymous
a b D Laptop
April 1, 2009 2:14:05 PM

I have the same problem of LCD going dark on my 700m. I have found that when I disconnect the battery and leave it on ac power the screen stays on.. For occurrences where the screen goes blank I disconnect the display cable connector (on the right side) and reconnect, the display then comes back on, for a while if the battery is plugged in, and permanent if the battery is unplugged.
May 30, 2009 8:19:34 PM

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?

Quote:
I have the same problem of LCD going dark on my 700m. I have found that when I disconnect the battery and leave it on ac power the screen stays on.. For occurrences where the screen goes blank I disconnect the display cable connector (on the right side) and reconnect, the display then comes back on, for a while if the battery is plugged in, and permanent if the battery is unplugged.

June 8, 2009 12:48:15 PM

check if any of your laptops have a reed switch- a small suspend switch below your right hinge that sends signal to the screen to go off when the screen is closed because if there is one then press it using a scribe and check the pressure on the spring holding it. Sometimes that could cause the problem and that is fixed for $...
June 15, 2009 6:32:00 PM

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.
June 22, 2009 11:15:59 PM

I had to fix one in class, we replaced the video card and that did the trick for us
October 10, 2009 8:05:31 PM

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 ?

March 11, 2010 2:53:45 PM

Hi, I was also wondering if anyone found a solution for this or possible solutions. My screen is black as well when turned on and never lights up, but the funny thing about it is that if you hold the laptop up to the light, you can very vaguely see the login screen. So does that mean that the video card is working or just old and needs replacement? I also tried the no-battery disconnect and the switch that locks the laptop but to no avail. If it is the video card, how easy is it to get a replacement? Ugg!
Anonymous
a b D Laptop
September 14, 2010 9:15:54 AM

Hi one of my friends computer had a same problem LCD screen blinks when start and goes off, actually not completely off, you can still see the Centrino® logo in dim screen,for a second or half a second, which i thought the problem is the backlight or the backlight inverter. but it wasn't a backlight or the inverter, the problem was the white plastic frame which holds the LCD, layer of plastic and glass inside the LCD screen which was broken i put the tape and it worked but it was not a easy job to find out what was the problem. only open if you know what you are opening because you won't be able to put it back together and you can easily break things because it has so delicate parts.
Anonymous
a b D Laptop
October 26, 2010 8:42:25 AM

I TOO AM HAVING THE SAME PROBLEM.. BACKLIGHT GOES OFF ON MY DELL STUDIO.. I THOUGHT DELL WAS A GOOD BRAND.. IT LOOKS AS IF THEY HAVE PROGRAMMED IT TO GO OFF JUST AFTER THE WARRANTY PERIOD!!
Anonymous
a b D Laptop
November 21, 2010 11:40:06 AM

I am having a slimilar problem, :pt1cable:  display is on then immediately off. external monitor works fine so probably not the video card. when i hit the suspend tab, flashed on again for an instant. in that instant it is perfectly colored and bright so.....
December 3, 2010 5:41:16 AM

Just got my LCD to work again if anyone is still looking for answers...

If you think your backlight that is out, you can check by turning on your computer and pointing a really bright light at the lcd to see if there's any dim images on the screen (i used the led on my droidx and was able to see the the login screen). If that's the case, read the following article to make sure you are capable of replacing the CCFL

This article isn't on the 700m but gives you a general idea on what you'll need to do.

http://www.laptoprepair101.com/laptop/2007/12/09/replac...

then order from ebay or any other site that sells it

http://shop.ebay.com/i.html?_trkparms=65%253A3%257C66%2...

Hope this is helpful

-yosh
April 6, 2011 8:55:23 PM

Just got my LCD to work again if anyone is still looking for answers...

In my case, the issue was fixed after I replaced the CCFL light bulb inside LCD.
You will need to disassemble the LCD to replace it. Not too bad.

I got the "Dell Inspiron 700M/ 710M LCD LIGHT/ Backlight 12.1 Wide" from ebay for $5.49.

-Jeffrey
June 16, 2011 6:23:04 PM

My problem was the reed switch. It was stuck.
!