http://www.electronics-online.co.uk/acatalog/Sony_VMC20FR_AV_Cable_AV_mini_RCA_VMC20FR.html I've got a cable like that which conveniently wires up to a plug on the back of a PS1 screen. It's got the 3 AV plugs on one end, a headphone jack type connector on the other except it has four segements (audio R+L, video and a common ground) instead of the three on headphones. I want to know of any US sources to get JUST the 4-pin plug. Don't ask why it was a UK page, first result on google, but it should be a US source
Have a look at Mouser's part number 171-7425, see if it looks right. (would post a link, but oddly can't at the moment)