The Sega Saturn is my favorite console, and a lot of my time developing and tinkering goes into it. As such, this page will be updated frequently as I explore this machine, and share what I learn.
I took the Saturn apart to swap the laser, and do some pin testing while I was in there. To open the Saturn simply remove the 5 screws on the bottom, and take the top off. Be careful, on some models the laser assembly and drive are not screwed on and will come out freely. When removing the drive ensure to disconnect the ribbon cable on the right and the 2 small cables on the left. at this point you can remove the drive and laser assembly from the Saturn. The laser swap is easy and self explanatory if you bought the $12 dollar full assembly instead of just the lens, which I advise. Remove the last cable, remove the screws, swap and replace. To access the main board you first need to remove the power supply and shield. To remove the power supply you need to remove the screw, then pop the plastic clip out via the bottom hole, and remove the 2 screws holding the power adapter. once that is out remove the screws holding the shield in and unplug the ribbon cable to the controller ports, then remove the shield. Now you have access to the mainboard. Good time to get some 99% Isopropyl and clean the dust off. You are now at the point where you can make mods and alterations, such as adding switches. I will go more into detail with that in a future update.
The above photos are the pinout for the Saturn rear communication port, zoomed in on the schematics to the areas of interest. I have not yet figured out pin 9, 10, or 11. Looking on ebay I noticed these cords cost about $100 dollars, that's not cool. So, I had my friend Jon 3D print me a few comm adapters, the information on the printing can be found here:
Using those, I wired up my own and saved $85.
The first thing I discovered is that pin 2 is power (pins are odd on top even on bottom, with the slanted edge being 11), the power is a signal line however, most likely used for the Saturn to Saturn link to let each system know the other is there, its not suitable to power a device. But I had a hard time finding the ground no matter what I tried. Then I discovered the metal shielding inside of the port acts as the ground ( I will need to explore this more). comm pin 1 and 2 are also midi 1 and midi 2 from the sound chip. the other 6 ports that I know of so far, which are in the photo in the above gallery, are transmit, receive, and serial clock, on comm pins 3, 4, 5 and they repeat in the same order on 6, 7, 8. The first 3 go to sh2 master, last 3 go to sh2 slave. I will update this page once I learn what the other 3 pins do. There is a team working on a way to run a couple of older emulators via this port, and I am hoping to replace the internal save with a non volatile memory that connects via this port.
With some help from the guys over at team Yabause, and some legwork, I have figured out the other 3 pins and will explain. the Saturn rear port has 11 pins but 12 are listed. 12 is the metal shield around the port and is the ground. pin 1 does nothing and pin 2 is 5v connected to a power supply. pin 8 is grounded to a the shield (follow the schematic above and trace the line). the other 8 pins are the ones that connect to the chipsets, sh2 master, slave, and audio. I confirmed the above schematic by opening the Saturn and testing the pins internally, as well as externally, because the port is hard to fit things into. At one point i touched pin 6 with ground ( I think it was 6) and the polarity reversed. I am going to need to look into that.
the button below will take you to a segaxtreme thread that is extremely helpful
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