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MIDI-Controlled Sega Genesis Video-Glitch – Part 1

A few weeks ago, I picked up an old Sega Genesis with the hopes of doing a little bit of tinkering (emboldened by my Game Boy customization projects).

The Genesis uses a Yamaha FM synthesis chip for sound, which might be interesting to dig into at some point, but my main goal in cracking this machine open was to try some video circuit-bending: apparently pretty easy to do, bridging the legs of the VRAM.

First, though, I didn’t have the little box that I need to hook the Genesis up to the TV, so, instead of trying to track one down, I decided to install component video RCA outs.

So, away we go!

The Sega Genesis Board
The Sega Genesis Board
A
A “VA7,” alas

After some poking around on the internet, I found that there are lots of different revisions to the Genesis circuit board, and this, the VA7, is apparently the least desirable. The audio is actually synthesized on a different chip, but Sega didn’t account for the difference in output volume of the new chip in the internal amplifier, so the sound has all kinds of digital distortion.

Well, that just means if I fry this thing, I won’t feel so bad.

Wires for component out
Wires for component out
Testing the component out
Testing the component out

Quick disclaimer: Messing with things plugged into an outlet is dangerous! I’m only doing this because the Genesis has an adapter that converts the voltage to 10V DC long before the power gets anywhere near the board.

When in doubt, only circuit-bend things that are battery powered. Think of how embarrassing it would be for your parents to explain that you died trying to get glitchy video from a game system.

Some quick audio mods
Some quick audio mods

Hearing the complaints about the sound on the VA7, I did a quick adjustment by adding a resistor to pull things down a bit, and a capacitor to roll off some highs (I think that’s how it works. Someone please correct me if I’m wrong).

I’ve since found someone designed a Crystal Clear Audio Mod, which seems a lot more involved (and likely better) than my “quick and dirty” solution.

Looks like it all works!
Looks like it all works!

Success! Next step: start glitching that video feed.

Check back for Part 2 soon.

“Inspiration does exist, but it must find you working.” – Pablo Picasso

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