April 2015 – Simon Hutchinson

29 April 201517 June 2016

MIDI-Controlled Sega Genesis Video-Glitch – Part 2

Continuing my Sega Genesis Project, now that I’ve got the video in a form my TV can understand, time to start messing with things.

Repeating my 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 (or wife and son) to explain that you died trying to get glitchy video from a game system.

Anyway, that said, time to start poking around a bit.

These are the Video RAM chips whose connections I’m going to bridge. They have 24 connectors apiece, and one on each is the power, one on each is the ground, everything else (I believe) is data. So all we’re going to do is send some of that data to the wrong places.

I’m going to poke around the bottom here, because the contacts are more accessible.

(By the way, the resistor and capacitor you see here are not my work, just an afterthought by the designers of the PCB.)

That looks pretty glitchy to me.

I’ve found a few points that give a variety of effects (relatively). The next step (next time) is going to be installing a way to control these. I’ve decided I’m going to start with a push-button system before moving on to the MIDI control for two reasons:

1.) Moving in small steps seems wise.
2.) I’ve used up this month’s tinkering budget, and I’m going to need a Teensy to get the MIDI working.

Until next time!

22 April 201517 June 2016

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!

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.

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.

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.

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

14 April 201517 June 2016

Custom “Pro Sound” Game Boys

my first two custom Game Boys, BUDO (left) and MIKAN (right) — My first two custom Game Boys, BUDO (left) and MIKAN (right)

Since the winter break, I’ve been tinkering around with some chiptune projects, and I’ve got quite caught up in the simultaneous progressive and regressive sound design of composing with chips of the 1980s and 90s. Perhaps its a stretch, but I believe this kind of cultural re-appropriation as directly akin to drawing influences from outside Western Music.

Philosophy aside for the moment, as my first gaming system was the original Game Boy, I’m particularly interested in the circuit-bending and customization artists are doing with these old devices, so I’ve been getting my hands dirty for the last couple of months customizing these two Game Boys that I picked up on Craigslist.

While a lot of the work was purely cosmetic, I did a “Pro Sound” mod on both of them, which basically is just bypassing the internal (noisy) headphone amplifier and putting in some RCA jacks. On the Game Boy Color here, I also bypassed the existing audio output capacitors with some bigger ones, which supposedly gives a bass boost. While I hope to do some more experimenting in the future, most of what I did to these two units was a matter of just following instructions.

I’m calling the original Game Boy “MIKAN.” Customizations:

Orange screen backlight
“Pro Sound” RCA Mod
Custom buttons, ON/OFF switch, screen lens, link cover, orange LED, and battery cover

The Game Boy Color, “BUDO,” has:

Green LED
Original (broken) speaker replaced with Nintendo DS speaker
“Pro Sound” with bass boost capacitors to RCA outs
“Anti-noise” decoupling capacitor

They both have their own peculiarities in terms of sound. BUDO has some sub-audio in its output (perhaps a result of the bass boost), and MIKAN, without a decoupling capacitor, sometimes has “clicks” at the start of sounds (perhaps related to the DC power somehow). I’ll post some sound samples as I keep working on my current project.

I have to say it’s really fun and rewarding to do these customizations. While I’m working on a piece now that uses these “instruments,” I’m also trolling Craigslist for another cheap Game Boy so I can do the customizations again (and try some new things).

Of course, lest I give the impression that I’m the first one to be playing with the ideas in the realm of concert art music, check out this fantastic piece by Matthew Joseph Payne, performed by Meerenai Shim, flight of the bleeper bird.