How to run a NES from USB power

I recently installed a NESRGB into my NES, and wanted to remove the RF modulator from the system because I didn’t need it anymore. Or so I thought…

As it turns out, the NES also routes its power in and out of the RF modulator board a few times before sending the power to the main board to power the console. “Well that’s no good”, I thought.

NES power circuit – Courtesy of Console5

I looked around online and found an article on Hackaday where someone was doing something similar to what I was doing, however they were still powering the board from a barrel jack, and in some revisions cutting up the chassis to use a multi-out connector. I also didn’t need a palette switch since I soldered my NESRGB to the default palette. A little overcomplicated for what I needed, but still a cool project, and inspiration to come up with something I could easily use.

So I fired up Kicad and played around with a few ways to route the component video and audio out the original ports and power the console. I was quite surprised to find out that you can connect a USB B cable into a port using the same hole that was used by the barrel jack on the original board. A couple layout redesigns later, and I came up with a fairly bare bones PCB.

My somewhat basic attempt at making a replacement board

Theoretically you could remove the LED and resistors. I had originally included it as an “idiot light” to remind me to unplug the console if I was working on it with the chassis open, but in retrospect it doesn’t really add much other than a small amount of power draw and some light shining out the back of the console (and maybe a little out the cartridge slot if you didn’t put the metal RF shield back on). The resistor on the USB connector can also be replaced with a dead short, as I misinterpreted the USB power delivery spec.

So after a few weeks of work and building one of these up for myself, I had found out that people have been making these for a while. I suppose I shouldn’t be surprised at this point, the console is 36 years old, and the NESRGB has been around for almost 10 years. That’s okay though, I needed the PCB routing practice.