I have some instructions for getting into a Toshiba service menu here
. The settings listed on that page are specific to my model and will vary on yours, but the basic controls are the same.
It is very important that you follow the instructions regarding WRITING DOWN EVERY SINGLE SETTING BEFORE YOU CHANGE ANYTHING
. If you don't, and you change something by mistake without knowing how to change it back, you'll be screwed. You'd have to call a service person for repair, and the fact that you've gone into the service menu voids your warranty.
Basically, if you're at all unsure of what you're doing, don't do it.