Adding RGB to the HiSaturn

The crown jewel of my vast console empire (snicker) is the Hitachi HiSaturn. Designed for portable and in-car use, it was available with a nifty active-matrix LCD screen. For reasons unknown Hitachi never included RGB output on the otherwise Sega Saturn standard AV output port. Imagine my surprise when I plug it all in and it doesn't work! This mod is quick and easy and adds the missing RGB output.

The HiSaturn is far more complex than your nromal Saturn system. You're going to have to remove about twenty screws, three sub-boards, two chunks of shielding, and a freakishly irritating blue wire that connects the two largest PCBs together, making any modification very difficult. Watch out for this wire! If you've got the time, cut it in the middle somewhere and solder it back together when you're done. Trying to attach it to the tiny little legs of the chip if you tear it off is a real pain. Trust me on this.

Theory

According to the datasheet for the Sony CXA1645 chip (Download here) chip pins 21, 22 and 23 are the RGB outputs, and they need only one resistor and one capacitor to for the signals to be output in a useable fashion. Simply solder a small length of wire, a resistor and capacitor in series from each leg and run it to the AV port pins on the underside of the PCB.
[ One Resistor to Bind them, One Capacitor to ...  Blind them? ]


The Map

[ HiSaturn PCB ]

This is about how the finished mod will look. For best results use 10v or smaller capacitors, as 16v devices may be too large to comfortably fit under the shielding, and there's not really any other place to put them. The HiSaturn is pretty packed inside!
[ HiSaturn PCB Map ]

1. AV Output Port
2. Serial / Link Port
3. Cartridge Port
4. AV Input Port
5. Sony CXA1645 Video Encoder


NEW as of October 2003:
[ HiSaturn picture ]

The Underside

[ HiSaturn PCB Underside ]

This is what you'll see underneath the Hisaturn PCB. Solder the RGB lines from the capacitors to the points shown, and you're done. I hope you can put the system back together - it's a fiddly bitch, but very awe inspiring in RGB. Next up: Territory mods. =)
This mod are from GamesX.com ( C ) Lawrence Wright
Spanish translation from Miguel Durán