Instructions
Purchase an HDMI-to-three RCA AV adapter from an electronics store. The cable will have an HDMI connector on one end. The other end will split into three audio-video cables. They are usually color-coded red, white and yellow.
Connect your PS3's HDMI cable to the corresponding end of the adapter. Connect the other end of the HDMI cable to the PS3.
Insert the red, white and yellow cables into the matching slots on the audio-video panel, usually located behind the television. The red and white cables should be inserted in the right and left audio slots. The yellow cable should be inserted in the video slot.
Turn on the PS3 and the television. Navigate to the input channel on the television and you should see the PS3 boot-up screen.