racketboy - sega saturn modchip dealer and retrogamer

Model 1 Sega Saturn ModChip Installation Guide

This Saturn is by far the most difficult because you need to have some skill with a soldering iron. The actual installation of the chip is quite easy once you have correctly altered the chip. Model 1 Chips are no longer in production, so unless you can find some backstock or place that has some left over this is your only alternative other than buying a model 2 system.

Tools needed:

  • Sega Saturn Mod Chip
  • Philips head screw driver
  • Solder and Soldering Iron
  • Razor or knife
  • Dremel Tool (Optional use for grinding Mod bard
Step 1: Altering the ModChip.


Not only does the Model 1 use 1 less conductor between the CD board and the motherboard, but some of the signals travel on different pins. This means it is necessary to re-route some of the connections on the modchip so that the correct data gets manipulated by the chip. The following images best demonstrate how to do this. Notice that in addition to re-routing the chip it is also neccessary to remove pin 21 from the modchip so that it can be seated into the motherboard of the Saturn.

Green: Traces to re-route
Red: Traces to cut
Yellow: Indicates pin 1 on the Chip

Technical Pinout
Pin 21 pin 20 pin
1 IC 20 315-5746 pin 7 [8MHz clock] pad B SH-1 Pin 79 logic HIGH
2 Ground Ground
3 SH-1 Pin 107 DATA/td> SH-1 Pin 107 Data
4 SH-1 Pin 108 Stop packet strobe[response byte?] SH-1 Pin 108 Stop packet strobe[response byte?]
5 SH-1 Pin 101 OE SH-1 Pin 101 OE
6 SH-1 Pin 100 Start packet strobe[command byte?] SH-1 Pin 111 WR strobe
7 Pin 111 WR strobe SH-1 Pin 100 Start packet strobe[command byte?]
8 Ground Ground
9 unused R48 [alternate 4MHz location diff rev.?] pad 0019 JP5 [8MHz clock]
10 YGR-019B pin 123 Ground
11 SH-1 Pin 79 YGR-019B pin 124 ??? logic low
12 Ground YGR-019B pin 125 Read strobe
13 YGR-019B pin 126 and 129 OE fetch data YGR-019B pin 126 OE
14 YGR-019B pin 125 and 131 [4MHz clock] pad 0014 Ground
15 XYGR-019B pin 130 CD buffer DATA YGR-019B pin 128 Data Read OE [?] active only during data fetch
16 Ground YGR-019B pin 129 OE fetch data
17 IC 39 VHC08 pin 2 YGR-019B pin 131 [4MHz clock]
18 YGR-019B pin 122 YGR-019B pin 130 CD buffer DATA
19 GR-019B pin 118 via 300 Ohm R175 Ground
20 YGR-019B pin 128 R47 (4.7KOhm), not sure where the other side of R47 goes ATM..
21 YGR-019B pin 121
Credits for this information go to Pinchy and ExCyber of Sega Xtreme

The pins that you have to cut and reroute on the modchip are 7,13,15,18 the hardest part is transferring 15->18.

C= plastic ribbon connector (where you plug in ribbon on modchip)
E= edge connector of modchip (part of mod that connects to Saturn motherboard)

What traces to reroute:
Cut pin 7 C -> pin 6 on EM78
Connect Pin 6 EM78->pin 5 C
Cut pin 13 C -> Cap
Connect Cap-> pin 16 C
Cut pin 15 E -> pin 12 157
Cut pin 15 C -> pin 14 157
Cut pin 18 E -> pin 18 C
Connect pin 12 157 -> 18 E
Connect pin 14 157 -> 18 C
Connect pin 15 E -> pin 15 C

Remove solder from pads 0019,0014
Connect middle pad -> pin 17 C
remove solder/jumper/connection from A/B pads
Conect pad A [8MHz]-> Pin 9 C
Trim off pad 21 with dremel and you're done.

Step 2: Installing the chip.

Assuming you have done the above step correctly the rest should be a breeze in comparison. Simply insert the chip into the motherboard and then insert the ribbon cable. For the 5v power you can splice into the red wire thats going to the power supply on the lid, for the Saturn that has the power supply on the bottom half you can connect to the im not sure yet.

Make sure you cut out any metal shielding near the modchip, you dont want it to accidentally contact something and short out! In some models of the Saturn the ribbon cable will barely reach, you can try to stretch it out a bit, or buy a longer one from digi key. You need 1mm pitch flat flex cable from and ZIF female connectors too. http://www.digikey.com/

The part numbers are:

Credits: Credits for images, Gogou, Seal1,and GivenBack. The actual method, original guide and the 20 pin pinout was discovered by Pinchy . Original Pinout of 21 pin by Excyber and Mal.

Disclaimer: I take no responsibility for any damages or harm that you may bring to yourself or your Sega Saturn Console by making the above modifications. All laws concerning the use of these chips and the back-up games they allow you to play are to be followed and I take no responsibility for any trouble you could bring upon yourself.