Instructions
Turn off the PS3 and disconnect the HDMI cable from the "HDMI Out" port. Insert the square end of the PS3 AV cable into the "AV Multi Out" port on the back of the PS3.
Insert the yellow, white and red prongs on the opposite side of the AV cable into the "yellow," "white" and "red" AV inputs on your TV. AV ports are generally located on the back or on the side.
Change your TV to its AV video display mode. Though it is usually titled "AV," it may also be referred to as "Input," "Video" or something similar. Turn on the PS3. After a few seconds, the PS3 logo will appear on-screen.