Posted on May 23, 2020
When the Sega Nomad was released back in ‘95 there were three power options available to gamers: 6 AA batteries, a 7.2v rechargeable battery pack, or the 9v DC wall wart adapter from the Model 2 Genesis. Oddly enough, the Nomad really only needed 5v to run. This got me wondering if I could power the Nomad off of a modern rechargeable battery and boost converter. After a little searching, I stumbled onto this YouTube video where a guy, who goes by “The SegaHolic”, was powering a Nomad with USB power (5v). But there’s a catch… you can’t run 5v through the original battery terminals on the back of the Nomad because it’s expecting 7.2v or 9v from those pins. An interesting solution however is to run the 5v and ground through the AV port, which is exactly what I did for this project!
Disclaimer: This post was written for informational purposes only. I assume no liability or responsibility for damaged equipment or for any injury you may incur attempting to replicate this project. Be careful when working with LiPo batteries and electronics.
Doomy Doomer’s Sega Nomad Battery Case
Note: feel free to remix and use this design for your project but do not sell or take credit for this case design. If you remix I’d appreciate a credit line and link back to this page.
Filament: Orange Prusament PETG
Sliced with: PrusaSlicer
Once you’ve printed the case parts, grab the super glue and set it aside. You should have the following printed parts: bottom, lid, bracket, and three alignment posts.
Before assembly anything, it’s a good idea to check to see if the bracket slides onto the back of the Nomad. Each printer prints different, especially overhangs, so there could be slight slope on the feet. If you do have issues sliding the bracket freely onto Nomad, try trimming off the some plastic on the foot that is causing the issue with an X-Acto knife.
The bracket should slide easily onto the back of the Nomad and lock into place with the bottom screw hole.
Once you’re sure the bracket is sitting properly on the Nomad, remove it and grab the three alignment posts, bottom case, and super glue. Obviously be careful with the super glue. You can glue your fingers together or even to the printed parts.
Let’s assemble the bottom section of the case. Start by aligning the bottom bracket to the bottom case the best you can. Then push each alignment post into place. I printed these parts at .20mm so my tolerances were snug but by no means tight. If the alignment posts are loose and fall out, tape them down. We want them to be able to defy gravity when applying glue to the bracket.
Next, grab the super glue and apply a thin layer on the backside of the bracket. Make sure you apply glue to the side without legs! Now, line up the bracket to the alignment posts and apply pressure to the post with one hand as you push the bracket into place. Do this for each alignment post. If you’ve done this correctly, the bracket is aligned perfectly to the bottom of the case. Put the bottom case aside to dry.
While the glue dries on the bottom case, let’s solder up the switch, PowerBoost 1000c, and USB port. We’ll start by soldering the power (PWR/Vcc) and ground (GND) wires to the USB connector that comes with the PowerBoost 1000c. These wires should be no thinner than 26 gauge and I’d recommend 24 to be safe. It’s also a good idea to measure out the wire length before doing anything further. You don’t want the wires too short that they won’t reach or too long that they take up too much space in the case. It doesn’t matter what colors you use for these wires but it’s probably a good idea to use black for GND and red for PWR. Look straight at the USB connect. The PWR (Vcc) is on the left and GND is on the right. Make sure you keep this polarity in mind when wiring up the connector to the PowerBoost 1000c.
Once you’re done soldering the wires to the USB connector, add some shrink to each wire and push the shrink up against the connector. Now, fire up your hot air of choice to shrink the tubes to provide rigidity. It’s especially important to use heat shrink here because the leads coming off the USB connector are meant to sit in a through hole PCB. The wires could easily break while working in the case without the rigidity of the heat shrink. Enough about the importance of heat shrink, moving on!
Next, let’s solder up the switch using 28 or 30 gauge wire. These wires will only be carrying signal so they can be thinner gauge. When you connect the PowerBoost’s Enable (EN) pin to GND, the PowerBoost cuts the battery power. What that means is, when the switch is thrown in the direction of the pins you wired to, the Nomad will be off. Because the switch will be mounted upside down, take into account which pins you wire to if you care about the direction of On/Off.
With the switch and USB connector wired up, we can now solder them to the PowerBoost 1000c. Here’s a quick and dirty diagram to show you how these components will be wired together.
Now that we know what we’re wiring to, let’s solder up the USB connector’s PWR and GND wires as well as the two switch wires to the PowerBoost. Adafruit did an outstanding job with labeling the PowerBoost. You should be able to clearly see the positive and negative through hole positions for the USB connector, so solder those up. Next, we’ll be soldering the EN and GND for the switch. It doesn’t matter which wires from the switch run to the EN and GND pins. Once those are soldered up, it’s time to add the components to the 3D printed case.
Grab the two M2.5mm screws and a screw driver. Place the PowerBoost into the case and screw it down. The case is self tapping but too much force could strip the holes, so don’t be too aggressive.
Next, we’ll add the switch. I made this case with a pretty tight tolerance, which is great once everything’s together but can be a pain to get components in initially. To help out, slide the switch to the middle before pushing it into the case.
Once you have switch lined up and push down, use your screw driver to gently push on the corners of the switch to ensure it’s truly secured in place. If you’re noticing a little wobble and that bothers you, you could always put a dab of super glue in the middle brace where the switch rests in the case.
Now let’s add the USB connector. It should just slide right into place and be held in by friction. There was something weirdly satisfying about pushing the USB connector into place and having it perfectly fit with no wiggle.
Finally, let’s add the battery. Connect the battery wires to the JST connector on the PowerBoost. The battery is held into place by the lid so no need to glue anything. Everything should now be nice and snug in the case.
Flip the power switch to the on position and you should see the PowerBoost’s blue power LED lit up like Christmas. If it does not light up, the switch isn’t wired correctly.
It’s worth mentioning the Powerboost’s LED status colors and what they mean. Blue is on, Yellow is to indicate you’re charging using the MicroUSB port, Green means the battery is fully charged, and Red means the battery is under 3.2v and will be shutting off your Nomad soon.
Finally, let’s pop the lid on. As I said earlier, I designed this case with tight tolerances, so make sure you’ve got everything lined up before putting force on the lid.
As cool as I think my custom 3D case is the real magic to this project is the custom AV cable that takes USB power to a 9 pin mini DIN AV port on the Nomad. This next part may upset some people but I used one of my many Genesis model 2 RF adapters for this part but I completely understand if you wouldn’t want to destroy something that’s no longer in production. I’ve listed the equivalent connector in the materials section but I’ll be focusing on what I used.
So let’s get destructive. Grab your Genesis 2 RF adapter and cut the end off that goes into the AV port. Leave plenty of slack for mistakes because we can always cut more off later. Next, take your spare USB cable and cut the larger end off (the type A end). Put the USB aside for a moment and let’s focus on the Genesis adapter cable we just cut. Use your wire strippers to expose the Yellow (video), White (Mono Audio), Red (PWR), and copper strands (GND). We only need the Red and copper stranded wires. Twisted the copper strands together to make a thick braided wire.
Now grab your USB nub you cut off and do the same exposing four wires. Not all USB cables are the same so you’ll probably need to use a multimeter if it’s not obvious what’s POS and what’s NEG. I’m just going to assume two of the four wires are red and black, which is all we need for this cable. Add heat shrink tubes to one side of the two cables for later. Finally, splice and solder the two cable together to make a very proprietary, yet very awesome, power cable. Shrink the tubes with your choice of heat.
With everything soldered and heat shrunk (shrinked? shrunken?) together, you should have a new fancy power cable that looks something like the below image. Before you start plugging things in, test the wires with a multimeter and double check everything’s correctly married together. The most important thing here is polarity!
Now that the hard parts are out of the way, the only thing left to do is to slide the battery pack on the back of the Nomad, plug the USB end into the battery packs USB port, and attach the AV end into the Nomad’s AV port. Throw the switch! If everything was put together correctly, you should see a power light on the PowerBoost and your Nomad should be powered on. That’s it!
This is a very simple solution to an age old problem and I hope all the Nomad lovers out there take advantage of it.