Question about Dell Latitude C640 Notebook

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Dell C640 powers off when lcd is plugged in

My Dell C640 works fine when plugged into an external monitor, but only with the lcd ribbon cable unplugged from the motherboard. When the lcd is plugged in, the computer powers off within seconds of being turned on. I bought another lcd, inverter and ribbon cable, but the same thing still happens. The only other problem is a battery that will not hold a charge (I have ordered another one). I don't know if the battery issue may affect the lcd problem but I mentioned it anyway.

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Re: Dell C640 powers off when lcd is plugged in

I have the same problem... if you remove the bios chip and then reseat it, it will work untill u leave it off for more then a day!

Posted on Jan 26, 2008

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Re: Dell C640 powers off when lcd is plugged in

There is a possibility that the socket for the lcd ribbon has shorted somewhere, either the socket itself, or the tracks on the motherboard leading to the power supply circuit or video card. If this happens then there is no DIY fix, unless you have PCB cutting equipment or a micro trace pencil. If you are desperate, you can also look into replacing the LCD's power inverter chip. They only cost about $30-40 and may fix the issue if it is blown and trying to pull way too much current.

Posted on Jan 08, 2008

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