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12487
September 14th, 2008 11:00
Intermittent Backlight
Inspiron 640m. My backlight goes out randomly. I can restart it by closing and opening the lid.
Control Panel>System>Hardware>Device Manager>Display Adapter has two entries for the chipset.Deleting one meant I had to reinstall driver via New Hardware Found on reboot. This may not be relevant.I reecently changed my antivirus s/w from AVG to Kasper*** for 24 hours during which the display was perfect, I changed back because I didn't like Kasper*** and the backilight problem came back. This could be coincidence.
My laptop is on for long periods, so I use it on cooling pad with 2 fans so I would hope nothing is overheating..
I'm not very techy - so any help/advice appreciated.
Gary
ejn63
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87.5K Posts
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September 14th, 2008 12:00
If there's an image on an external monitor when the internal one goes dark, contact an LCD repair shop to have the backlight replaced.
The cost should be $100-150.
Falconx211
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33 Posts
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September 15th, 2008 00:00
Hi Garytilt,
I had a similar proble with my HP laptop. The backlight would go out and I would have to reboot to get my screen back. Eventually the screen died and would not come on at all. It is possible that the backlight is bad, however ccfl lights usually work or they don't. It sounds more like the inverter board is having issues. This board connects your ccfl lamp (backlight) with the power supply and mainboard in your laptop. I replaced the inverter in my machine and everything was back to normal. If you dropped your laptop or banged it around a bit it is possible that you loosened a wire connection on the inverter board.
I would reccommend as a first step to opening up your display and checking the connections. The inverter is typically located below the LCD panel, so you only need to remove the front part of the frame. Second have the inverter tested for proper functionality. Last, replace the ccfl lamp. If you are unconfortable opening up our machine do not do it. It is easy to mess things up with how compact laptops are. Have a tech savy friend or tech service do it.
I can not say for sure this will work or that it is your actual problem. I offer this as a suggestion based on my own experience compared to the symptons you describe. Good luck and I hope you can get your machine working top notch again.
Garytilt
2 Posts
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September 15th, 2008 13:00
What I find curious is that when the backlight goes out; to restart it, all I needto do is close the lid and reopen it. It is not necessary to reboot.
I would like to know what turns the backlight on
On other laptops I've owned there was a tiny pin/button that was released, near the hinge, to activate the screen - I can't see anything like this on my Dell.
Anyone know the answer?
Gary
ejn63
9 Legend
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87.5K Posts
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September 16th, 2008 13:00
On most of the newer systems, there's a switch built into the mainboard activated by a magnet in the lid. Check to see if the external monitor image goes out when the internal does - if it does, it could be that switch. If it doesn't, it's not the switch.