I got myself a free tuner card after salvaging it from a relative's old PC after transferring their data to a new box and this was what inspired me to give MythTV a go in the first place. It was a bit of a challenge getting it to work, so I thought I'd publish what I did in case someone comes searching via Google and finds this info of use.
The TV card has the following chipset markings:
Conexant
fusion 878a
25878-13
E32731.1
0024 Korea
The tuner has the following:
LG TAPC-i701p
(It's a PAL tuner)
The PLL crystal has markings indicating it's 28 MHz
On the circuit board itself:
PMC 878TV (rev.3f)
(PMC = Prolink, so it's a Prolink 878TV rev.3f)
Modprobe can't auto-detect through the firmware as there's nothing there to check, so you have to provide the parameters manually. The following settings worked for me:
modprobe bttv card=37 tuner=26 pll=1
You can find more details on what these settings mean at the BTTV howto:
http://www.tldp.org/HOWTO/BTTV/index.html
To make these permanent, edit "/etc/modprobe.d/aliases" and add the following line: (Without the quotes, obviously.)
"options bttv card=37 tuner=26 pll=1"
Hope that helps someone!
