So the parts have arrived, resistors, capacitors and Phono sockets. It was time to start the soldering. First I soldered the wires to the sockets in readiness, adding the resistor and capacitor to the video line as per the instructions at http://hackitup.tumblr.com/post/548848692/sms2videoaudiomods which seemed to concur with other sites I checked.
With the wires etc. soldered onto the sockets I opened up the Master System console and removed the main board (actually the only board) and located the Sony CXA1145P chip and marked the pins I’d be using to solder to. A little tinning on the wires and a bit of fresh solder on each pin connection pad and it was time to put wire to pin. Being old and large chips rather than todays tiny surface mounts components the soldering is relatively easy and in no time the sockets were in, the wires connected and the Master system ready to test. All plugged into the TV and power on, and nothing!!
I opened the console back up and removed the board to find one of the wires had snapped from being bent into position. Resoldered, re-assembled and retested, and this time the Master System displayed composite video on my TV, and mono sound could be heard too. Another success then. All I will say is that the picture is good but I have a bit of brightness / colour drift as I play games on the Sega. It’s not terrible or anything but noticeable. It’s still better than trying to tune the Tv to the RF output and having it wander around trying to fine tune automatically.
I also searched out my Mega Drive 1 and found it still worked and I had a composite lead for that too. So more Sega fun was had with the 16 bit big brother of the Master System. Happy Days.