820-2850 backlight wont come back if mac is on and not used for a while

[Vinny]

I have this board, backlight is OK while computer is on, but if you don't use it for like about 5-10, screen turns dim, this is normal. But when you hit any key or anything, backlight wont come back, although the screen is working and computer on. Any help?

 

[dukefawks]

Never seen that before. First inspect for corrosion of course. Then measure voltages after this has occurred, see if BKL_EN is still there and see what the output is on the LCD connector.