During my deep-dive into the N64's anatomy, I wanted to come up with a way to simplify rewiring of the cartridgle slot, once the original footprint is trimmed off of the N64 motherboard. I started by making a flex PCB that solders to the RCP on the N64, which leaves only the PIF lines (excluding PIF-6), CPU-57 and Sync to be manually soldered. All connections are run over a 40 pin 0.5mm pitch FFC cable to a receiver board that fits an aftermarket 50-pin cart edge connector. Not much has been done with the design since I proved it works, but I plan on integrating the design (or some offsprint of it) in my own N64 portable. I did scale down the flex to a simple breakout board for manually wiring the RCP lines to the cart connector, mainly to retrofit into builds that require RCP wiring (such as the N64HHv2 by Nicholas298.
I created the following document to keep track of the RCP-FFC-Cart connections. An xlsx version is included in the repo as well.
This flex solders directly to the RCP on the N64. The only handwiring required is for PIF-1, PIF-3, PIF-5, PIF-7, PIF-23/24, CPU-57, and Sync (on the video DAC). Keep in mind that multiple PIF pins go to multiple places on the N64 motherboard, not just to the cart slot. As per the N64 trimming guide, those lines need to be wired to all of the marked locations.
I made two receiver PCBs for the replacement 50-pin cartridge slot. One with the FFC facing the front of the cartridge (not ideal for integrating into a portable), and one with the FFC facing the back of the cartridge (more ideal). I would recommend only using these boards as references, as they were not made with any kind of portable in-mind, and have an incorrect footprint for the cart edge connector.
FFC facing the front of the cartridge:
FFC facing the back of the cartridge:
I did not check the row-to-row spacing for the replacement 50-pin connector, so it will not fit into these boards as-is. The pins need to be bent as shown if you want to use these boards.
After testing the flex on a stock N64, I tested it and confirmed functionality on a trimmed board.
It's an RCP-FFC... without the FFC! It makes RCP wiring a whole lot nicer than soldering right to the IC. It does not include any 3v3 pads, as it can be pulled from a nearby source on the N64.
- YveltalGriffin: Answering my million questions and proving tips for designing flexes
- Gman: Helping me learn the N64's anatomy
- SparkleBear: Getting me into the N64
- BitBuilt: Being the best modding community out there!
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