For those of you in the know, Sony uses a wired remote
called a "Rotary Commander" for most of their head units. This remote uses a
normal 3 conductor 1/8th" head phone jack to transmit functions. This is done by
differing resistance across the wires, which indicate which button is being depressed.
I got particularly bored today, so I mapped it out with my DMM as best I could. The possibilities are endless (rear seat controls, steering wheel controls, external interfaces, etc).
Inside the wire, there are three elements: the Red, White, and the shield. Most of the connections concern the shield and red wire. The white wire, however, is needed for disc +/-. This wire will have about 60 ohms across it whenever the top knob is pressed in. This tells the unit that the track/preset +/- will actually be the disc +/-. If you want to use disc +/-, the track +/- will have to be used while a 60 ohm resistor is placed between the shield and white wire.
The resistors are the normal 10% tolerance resistors, only much smaller. Be aware that you can combine many functions by pressing two or more buttons at the same time.
With the rest of the wires, the shield and red wires are used. Here are the resistances:
|Vol +||16.91 k|
|Vol -||23.65 k|
|Track -||12.18k||Must have white wire bridged to shield with 60 ohm resistor|
|Track +||8.86k||Must have white wire bridged to shield with 60 ohm resistor|
|Audio||2.2k||Pulses momentarily, maybe error readings with DMM|
|Band||2.2k||Pulses momentarily, maybe error readings with DMM|
|Preset +||6.6k||This is the front right button. Could not determine function.|