Shuttle SK41G TV out problems

I recently purchased a Shuttle SK41G from eBay and I'm trying to get it
set up with Mythtv. My problem is that I am not getting any output from
the built in tv out s-video port. I've spent all night googling and
still no dice so any advice would me much appreciated.

The video card is using the 'savage' driver (1.1.27t) and I've
connected it up to the tv using a s-video - composite cable that works
fine with my powerbook.

I've fiddled with my XFree86 config a bit and added the "TvOn" and
"PAL" options - The log reports "TV enabled in PAL format" but still
nothing. I've tried starting up with no monitor attached and the tv
still stays blank.

I've run the 's3switch' command and it reports that "CRT TV" are active
and the tv is "NTSC-J". I tried running "s3switch TV PAL" but this just
put the monitor into an unsupported resolution and the tv still did
nothing.

Perhaps I just need a better XFree86Config file (from someone who has
this working)? Or is there a BIOS setting to enable the s-video port
(not that I can find)? I'm far from a linux expert so if anyone can
suggest any further avenues of investigation I'd love to hear them.

Cheers

James