laptop screen dim, motherboard

[htdspro]

I own an HP laptop, model Pavillion g6. The screen is extremely dim, I can really only see the screen and icons when holding a flashlight to the screen. I connected the laptop to an external monitor, works perfectly, so video card should be ok. Checked all display properties, brightness, etc. Did my research, this is what I have done thus far:
1.Replaced LCD screen with new LCD screen, same result
2.Re-installed old screen again
the laptop do not have any inverter
3.Installed new LCD display cable, same result

1. 
   
   • Could there be an error with the motherboard?
     Is there any display fuse on the laptop motherboard? Not on the LCD!
     ANY HELP/SUGGESTIONS WOULD BE GREATLY APPRECIATED!

[JorgeM]

Sounds like it could be a component on the motherboard/power from the motherboard. You did very well with your troubleshooting being able to rule out the screen itself and the video card.

[htdspro]

thank you, but do need help on this...