A single electronics site where I can find everything related to LCD monitors would be great.
Often its less trouble and less expense to buy a new one.
LCD Monitor Repair and Fixya are two of the top sites for troubleshooting -- but the former gives you access to circuit board diagrams, which is what you need. Circuit components are visually explained to reveal the best way to fix a monitor based on model type and known problems. Its updated e-library is a great reference for troubleshooters, including those who like repairing gadgets on their own. It's easily my favorite for hands-on projects, both electronics hardware.