I've found this pinout:
View straight on. 4 pin din.
_ _
.' V `.
|1 2|
`.3 4.'
`---' Shield
1 +5V
2 +12V
3 Ground
4 Unknown
What is this Unknown pin used for? Is this pinout viewed at console or at cable? the site says: "Put a ground jumper from pin 3 to the shield." what jumper is it refering to?