The Sega Master System II was the first console I bought with my own pocket money, and I hold fond memories of it. I got paid 50c a bucket to weed our 3/4 acre back yard out in the country, and I saved for that console 50c at a time.

To cut back on costs from the original Master System, Sega removed the A/V out port at the rear of the unit, opting to connect only via an RF encoder. 20 years ago I didn't care. Today with all my RGB monitors, I start to notice just how ugly it is.

My best friend brought his SMS2 console around the other day, and mentioned the effort required to play it on his new tunerless LCD TV. Then a little voice entered my head: "it's moddin' time!"

*Click thumbnails for bigger*

Prying the sucker open, the chip nearest the RF-out is a Sony CXA1145P. Google leads me here:

http://pdf1.alldatasheet.com/datasheet-pdf/view/77344/SONY/CXA1145M/datasheet.pdf

Score! Mono audio out, Chrominance/Luminance (Y/C - or "S-Video" as it's known) out, compisite video out, and a common ground. Piece of cake.

First, down to jaycar to buy some bits and pieces. These chips spit out a raw signal that's too low for TVs. Coming out from the chip, first I place a 75 ohm resistor (standard load for video out) and then a 220uF cap, nagative towards the TV. This acts as a small amplifier, boosting the signal.

I grab a 4-pin mini din female (S-video) and 3 female RCAs, drill some holes in the case, and whack them in (yes, the drill bit went for a walk on the yellow RCA plug hole - not happy):

Next comes the soldering. The composite video out, and both the Y and C signals of S-Video all get the resistor/capictor pair. I put dual RCA on for audio out, but merely wire them to the same output (the Master System only had mono sound, and I want to make it so that my mate doesn't need to buy a splitter). No amplifier needed on the audio out. All grounds are wired together, and connected to pins 1 and 24 on the Sony chip (both ground).

The SMS2 has an interesting metal cover inside that acts as a giant heatsink. Squeezing all the wires around it was a bit of a pain, but the cover goes back on, and the unit is ready!

I hook it all up, and enjoy the fruits of my labour with some RC Grand Prix in all of it's crystal clear S-Video goodness.

Everything works well except for one bizzare thing: the title screen of Alex Kidd In Miracle World (built in game) loses sync when using S-Video out. All other parts of the game including ingame stuff, pause screen, amd even the SEGA logo are fine. All other games are fine 100% of the time, and Alex Kidd is fine when using composite video. Oh well, not to worry. It works 99.99% the way I wanted, and my mate is stoked.

Very easy mod, and a great result.

This is the same video chip found on most early Sega consoles, and other brand consoles too. For folks wanting to do the same, take a look at the following two images: