ibook g3 700MHZ dim screen

hello everyone, my first time asking a question if anyone can help.
My Ibook (700mhz g3) screen looked at first was not comming on. closer look reveals its dim but functioning. you can hold a light to it and you can see the desktop. I pluged an external monitor and no probs and image is there, which I assum its not the graphics card. googled it and found maybe pinch cable or inverter but not the case cause I swaped the screen with a good working screen including all cables and inverter and still dim. Anyone have any ideas what maybe causing this? I am at a lost! Thanks if anyone can HELP!!

Maybe your iBook has a dying logic board?
Those seem common for the white G3s.
Just a guess though, sorry.
Do a google search on something about the iBook G3 video problems.
Someone else should be able to help out more.