Thanks Don
I found a Schematic for a Logitech FS300 at
http://www.oldbmw.com/other/technojazz/FS300/

It looks like in one case the sleeve/ring are grounded, second case -sleeve/tip, and third case (by the use of steering diodes)sleeve/ring & tip are grounded.

[This message has been edited by Gord (edited 01-17-2003).]