The Model B+ features a new 3.5mm audio jack which also includes the composite video signal. This has allowed for the removal of the composite video socket found on the Model B.
The new jack is a 4-pole socket which carries both audio and video signals and is often found on other multimedia devices such as iPods, MP3 players and smartphones. It now used on the A+, B+, Pi 2 and Pi 3.
This style of connector is sometimes referred to as “TRRS“, which stands for “Tip-Ring-Ring-Sleeve”.
Cables are readily available but they don’t all follow the same standard so you need to be careful before assuming it will work with your Pi.
The good news is that many will still work but you may need to swap the video cable for one of the audio channels. Cables where the ground connection is different are the ones that should be avoided.
Here is a table showing the configuration of various popular devices :
|Device||Sleeve||Ring 2||Ring 1||Tip||OK?|
As you can see from the table all the cables where the ground in on Ring 2 will work with the Pi although the camcorder style will require you swap your Video with the Right Audio plug.
Traditionally composite video uses the yellow coloured sockets whereas audio uses the Red (Right channel) and White (Left channel). Cables are available with both RCA plugs or RCA sockets on the end. Make sure you buy a cable with the appropriate connectors for your video and audio accessories.
If you’ve got a multimeter you can check where the ground is on your cable. Check the continuity between the rings on the cable’s 3.5mm plug and the outer metal shell on the coloured RCA plugs. If the shells are connected to “Ring 2” as shown above your cable should be OK.