mono/stereo on multislots

I've found a load of pinouts that all claim pin 11 carries mono sound on 2-6 slots.. but on both my old 2 slot and now my 4 slot there's no sound on that pin at all. are the pinouts all wrong or am I missing something?

Pin 11 should correspond to the Jamma speaker positive pin, so I would think that maybe the problem is that if you plug a multi-slot into a Jamma harness the Audio ground wire that corresponds with that on a Jamma harness would be on pin M which is the Test switch on a MVS board.

My post in this thread shows the circuit for mono out (pin 11) on an older version 4-slot. The newer one (which you probably have) is nothing like that in this respect but I have never tried to get sound from pin 11 on that.

http://www.neo-geo.com/forums/showthread.php?threadid=72013

actually the "usual" jamma speaker + pin is pin 10, briggs..

on my newer style 4-slot and my old 2-slot there was no audio on pin 11 at all, not even unamplified.