So, What’s Inside a Sega ST-V Game Cart (And Differences)

Over the past few months I’ve picked up a few Sega ST-V games.  The ST-V was an arcade system based on the Sega Saturn.  The budget arcade board of it’s time as the main Sega releases were all coming out on Model 2 and Model 3.  The CARTs are quite big and I want to see what’s inside so this post is just about opening and having a look around.


A Stga ST-V cart (Front)

This is the CART in question a very silly Colums like game called Baku Baku Animal. Looks pretty easy to get in to.  Clips on the top and two screws on the back bottom.


Retaining screws

Annoyingly, these are security screws and they are in quite tight.  I know this is done for ‘reasons’ but it’s very annoying.  Happily I have a tool.


Stupid  Security SCrews

This is a 4.3mm ‘Game Bit’ that I bought to open up SNES CARTS.  It fits these security screws perfectly though. Remove the two screws.


4.3mm Game Bit

Once the screws are removed the bottom of the case can be seperated and these two tabs/clips can be pressed to seperate the top of the cart case.  These feel quite delicate though so be careful!


Top retaining clips

Once open we see the front of the cart.  It even fills most of the  space inside the plastic shell.


Front Removed

Taking the PCB out and looking at the front side, everything is really well labelled.  There’s a row of ROMs at the top, filter CAPs in the corners, a couple of ICs (Octal Bus trancievers) and a custom Sega chip at the bottom (guessing this is the program ROM).


ST-V Board Front

The Rear of the CART has space for more ROMs but this is a small game so not used.  Just a row of Octal Bus Trancienvers.  These are used fo 2 way communication (Async) between the ROMS and the controller chip/system.


ST-V Board Back

A close up of the trancievers. All the same part: “3-STATE Octal Bus Transceiver” (guessing the 3 states are send, recieve and off)


IC line

Here’s a close up of the game ROMS.  These are 32Mbit ROMs.  Specific to the game on the cart.


So that’s the inside of a Sega ST-V cart.  I did then take apart another game that I had issues with, Decathlete.  This game was working finemost of the time but had a habbit of freezing at random.  I was worried it was bootleg So I opened it up…


Sega Decathelete

And found this.  From research this is legit and how it came from the factory but the program ROM is a socketed EEPROM (like the ones used for NAOMI BIOS chips (Same label and font).  It’s not super visible in this picture buy 1/4 of this chip was loose in the socket.  Pushing it back down again seems to have solved my issues of freezing.


Socketed Program ROM

The other interesting item on this board is a Sega branded chip the 315-5838.    This is not present on any of the games I have with non socketed Program ROMS (I opened a few others.  I Think this is a comms / decryption chip to stop people simply copying the EEPROM.  I can’t be sure though.


Custom Sega Chip

So that’s the inside of a Sega ST-V cart.  Actually more interesting than I initialy thought and a good example of a mid 90’s budget arcade system.











About Alec Dunn (LegoYoda)

Alec is an IT Architect focused around large private / hybrid cloud design and automation. He's also a big fan of the 'arcade' culture and games of yesteryear and loves taking things apart to see how they all work.
This entry was posted in Arcade, Games, retro, Sega ST-V, Software, Teardowns and tagged , , , , , , , , , , , , , , , . Bookmark the permalink.

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