backlight refuses to work

Im having a very strange problem with a dv8000. The backlight will not turn on. I have taken the whole LCD assembly off of the laptop and put it on another dv8000 and the screen worked fine. I also put a known good screen assembly in it and it still didnt work. The screen is working i can see a dim image on it but the backlight will not turn on. So is this the motherboard? Is there any way to turn on the backlight? I just replaced the motherboard in this laptop so i need to know if i need to return it for a replacement.

Things i have checked
Inverter
Ribbon cable
Lcd backlight it self.

 

There's a dim image on your laptop screen so that rules out the video card. You've tested the sceen assembly on another unit and so that rules out the ccfl and the inverter.

BTW, is your inverter in the lcd assembly or in the laptop body?

If the inverter was tested along with the screen assembly then there must be a power issue to the inverter.

I see you just replaced the motherboard. Double check all your connections. Some inverters are connected passively and others directly through fasteners. You may also need to check the continuity of your wiring.

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The inverter is in the screen assembly it self and has been tested. Also there isnt many connecters on the motherboard. There is a modem connector a USB daughter board connecter, the power jack connecter and one for the speakers, other then that there isnt much else in it. Im going to recheck the keyboard assembly with the good one from my other dv8000 maybe the button to make it brighter is bad?? Thats my last gusse.

 

No, the keyboard control will only dim the lcd but not power it off unless you mapped a keystroke to do so. Since you see dim images, it's not a suspend/hibernate problem either.

Connect an external monitor and check your bios settings. Your new mboard may also require a newer version of bios.

Let the seller know what your experiencing. Don't do anything to void the warranty if you have one. If all else fails, return or exchange it.

 

There are no options in the bios and i have reset it many times. I did update the bios from f17 to f24a and no luck. I gusse i have to return it.

 

Yea, looks like it.

 

the backlight of my dv8000 is not working as well. I am suspecting the inverter and am waiting for my order to arrive.
Can you tell me what's going on with your lcd? is that because of your motherboard?
I guess this is not the problem of the ccfl as there is little chance for both lamps to burn out.