Sega Master System S-Video Mod

Sega Master System
The glorious Master System complete with light gun and 3D glasses.

The Sega Master System is one of the most underrated game consoles of all time. There, I said it. In a world where the NES is seen as the defining 8 bit system, there seems to be little love for Sega’s first international console. To me, the Master System is the perfect console for classic 8 bit graphics, but while 8 bit graphics have been making a comeback, the Master System is being ignored.

8 bit graphics are now “in” and there are a huge number of 8 bit style games that have come out over last few years. What’s odd is that the NES seems to be seen as THE system for 8 bit, while the Master System is almost forgotten. I find this strange because, in my opinion, the Master System produces the classic colorful 8 bit graphics that seem to be in, while the NES is a bit more… well drab. Now, I’m not bashing the NES. In fact, I truly believe the NES is one of the greatest systems of all time, however, the colors on the NES just aren’t as good as the colors on the Master System.

According to what I’ve read, the NES has only around 54 unique colors, and can only use 12 at once, while the Master System has 64 unique colors, and can display 32 at once. This means that the Master System can pull off more colorful images than the NES. Of course, when it comes to graphics it’s all a matter of opinion, but I believe that the more colors in the Master System’s palette really shows!

Fantasy Zone II
The Master System has some truly impressive colors!

For a great comparison of classic console color palettes and other information, here’s a helpful Wikipedia page:

So why am I rambling on about 8 bit graphics and color palettes in a post about an S-Video mod? Because to me the Master System’s gorgeous graphics need to be experienced on something better than the stock RF adapter! RF never does anything good to classic game consoles, and the Master System is no exception. When I got my Master System earlier this year, I loved the colors and sprites in the games, but I knew that it was in dire need of an S-Video upgrade. I started refurbishing a couple of Sega Genesis systems recently, and seeing as how the Master System S-Video mod is the same as the Genesis, I decided to mod it at the same time.

Note, the pin numbers are correct in this image, but pin 12 is located on the right side of the chip, not the left. Go by the labels on the Master System board.

I went off of these 2 diagrams, one of which came from this thread here:

Sega Master System
Sega Master System ready to be disassembled.


Sega Master System
Master System with the top cover off.


Sega Master System
I started by cleaning the plastic top.


Sega Master System
Here’s the Master System board with the shield off.

The Sega Master System has the same encoder that’s used in many early Sega Genesis models, and it natively outputs S-Video. It’s a shame Sega didn’t take advantage of that, and simply add S-Video to the Master System or Genesis. In fact, they didn’t even add native composite support, even when the NES (which is older than the Master System) supported composite out of the box.

Sega Master System
The Sony CXA1145 Master System video encoder.


Sega Master System
I soldered the transistor legs and the cap leg directly to the pins on the video encoder. The great thing about the older systems is that the pins are massive compared to modern chips, which makes for easier soldering!


Sega Master System
I taped the wires down, and ran them to an S-Video port I added on the back of the plastic top.

I then added a audio jack on the back which is necessary because the sound was originally output through the RF cable. The Master System doesn’t support stereo sound, so I just added one jack. With just one jack, my TV still plays through both speakers.

Sega Master System
The mono audio jack I added to the back.


Sega Master System
S-Video and audio jack.

At this point I tested the video and audio output. At first I had luma and chroma swapped (noob mistake!) but after fixing that it worked like a dream!

I took a couple of pictures to try and show how clear the image is! However, when taking a picture of my TV, the colors were washed out, so ignore the colors.

Sega Master System
The colors in the image are washed out, but you can see how sharp it is!


8 bit Mickey never looked so good!

In the end, this mod did produce some jailbars (pattern of vertical lines running across the screen) but it doesn’t ruin the image. In fact, it gives the image a sort of textured look that I kinda like!

Also, just in case anyone was wondering, the light gun and 3D glasses both work perfectly fine after the s-video mod. So you can play Missile Defense 3D in crisp, clear s-video quality without worrying about incompatibilities 😉

So after doing this mod and seeing how sharp and bright the Master System looks, I’ve been researching how to do the same with my NES. Unfortunately, there doesn’t seem to be an easy (or cheap) way to do this. But I’m not going to give up! I will find a way to get s video from an NES, and when I do, I’ll be sure to post it here 🙂

As a side note, I know that this mod is possible on a Sega Mark III. Oh Sega Mark III, someday you will be mine!!!

Sega Mark III


    1. Honestly, I’m not sure. I suppose it’s possible to get composite from that port, but I can’t say for sure. They advertise it as Master System compatible, so if it doesn’t work, you can always get a refund from Amazon.

  1. Nice post, man. But in this Sony CXA 1145, C is not supposed to be in pin 15 and Y at pin 16? I’m asking because they should be in the same side, and appears you soldered one in each side.

  2. Hi,
    Did you take your audio output directly from the AV output? Or did you get it from somewhere else on the board?

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