When folk ask that, they usually have been reading or asking on other boards so the real discussion starts when folk reveal they are starting their career as a TV repair person. I suggest you find the service manual first and follow the diagnostic tree there.
Such manuals are not free and many times folk give up right there.
Hello i own a sony bravia kdl-40xbr4 had it for 3 years now. Just recently i started getting 2 white fuzzy lines going across my tv and as time goes by it gets stronger. Eventually the whole tv turns green in color which your still able to see the characters on the tv but very hard to watch. I left it unpluged for 10 min or so and once turn on again it was gone. After 5 minutes of viewing it started doing samething all over again. Tried different hdmi cables, RCA cable and different inputs but all the same. Also tried it with a different receiver thinking it was my comcast box but no luck. Does anyone know what this can be? Can it be the tcon board or possible the lcd panel? Please any help will be great.