Thursday, July 11, 2013

Super Joy 3 NES on a Chip Modifications

As a preface to the ongoing project below, as usual I was wandering Ebay and I happened upon a used Super Joy 3 for $8 so I couldn't say no. It is a "Famiclone" or also known as a NOAC (Nintendo on a Chip) meaning it is a cheap Chinese reverse engineered custom ASIC of the original NES. The beautiful thing is that is has a onboard Famicom 60 pin slot to accept original games. This can be rewired to accept US NTSC 72 pin NES games. So I set about making these modifications in order to build my own tiny portable NES. The only thing that stands between me and my dream is that I lack a 72 pin NES cartridge connector and I dont want to buy one if I can help it. So how did I work around this problem? Ingenuity!

I simply took an old ATA PC motherboard and desoldered the PCI connector slots from it with the help of my handy heat gun (warning it may look like a hair dryer but it gets MUCH hotter!) as I noticed it was about the right fit for the NES cart edge connector.

One problem is that the 72 pin card is much too wide so I needed to cut and splice two sockets together. Here I marked off where to cut by opening up a NES cart for reference and used a small hacksaw.

Looked like a good fit. But the PCI slot has many more pins than necessary and the alignment was a little off so some had to be removed with pliers to insure there were no shorts.
Both sides were now finished so I set about finding the right fit and tediously testing each pin with my multimeter. Overall everything fits like a glove.

Now I needed to add some plastic spacers to connect both sides and give some mechanical rigidity
 so I added some scrap black ABS plastic cut to size with my Dremel and glued with some super glue.
Finally I soldered the 60 some pins with IDE ribbon cable and rechecked the connections with my multimeter. Notice how the center five pins which would be located at the black plastic are not connected on either side. This is because these were brought out to the bottom expansion port of the NES which was never used to I left these pins out.
This is where I left off for now. I still need to remove the Famicom cart slot from the Super Joy 3's PCB and solder in my FrankenCart Slot. I'm keeping my fingers crossed that everything works. If not then this was still a good exercise in modifications. I'll update this page when I make more progress.