Motherboard Issue (Game Disc Unsuitable)

[mrandyk]

Hi Everyone,

I have a NTSC Model 2 Saturn that no longer reads game discs (official or otherwise) as being playable. It gives me the message "Game Disc Unsuitable For This System". The system apparently recognizes that this is a game disc judging by the message, but will only play the audio tracks.

If I insert an AR cartridge I receive "Cartridge Unsuitable For This System".

The system is modded with a chip, but I've bypassed that by removing it from the ribbon cable slot. Everything worked when I used the system last - about 2 years ago.

Finally, I did buy a second Saturn on eBay with a broken disc drive and swapped the motherboards. This got me up and running so I know that nothing is wrong with the disc drive. Any ideas what is wrong with the motherboard and how I might be able to fix it? I'm hoping to keep all Saturn parts away from the graveyard.

 

[JDE]

You are doing well keeping any Saturn parts out of the coffin my man! I have two Saturns in bits im working on right now replacing the lasers i got off ebay. Ive yet to come across your interesting motherboard problem though i will say this...it is a mirricle any of these consoles are still working in 2019, since according to the holy golden manufacturing rule book, they were only meant to last long enough until the "next" system got released. I have just searched youtube for motherboard issues and have not found anything yet. If you have the time you could ask-give details to this fella.
Shane McRetro
I have used his vids to fix stuff in the past but he is very busy and may take awhile to reply.
Good luck!!

 

[antime]

If the system has been region modded, verify that the mod hasn't failed.

 

[JDE]

^ awww man, Mr antime sir...is there a link kicking around to info on "how to verify mod failure" S.O.P.?
Probably going to need that myself at some point.

 

[mrandyk]

If the system has been region modded, verify that the mod hasn't failed.

To my knowledge the system was not region modded, but I did purchase this system already modified (via a chip in ribbon cable slot) some 10+ years ago. I happen to have one Japanese game that came with the system but I don't believe I was ever able to play it due to region lock.

Looking at the board it doesn't look like there was any work done. It seemed nearly identical to the one I pulled out of my 2nd Saturn.

 

[antime]

The "Game Disc Unsuitable" message means that the console has read the game header correctly from disc or cartridge, but that the region code in the header doesn't match the region code of the console.

In the Saturn, the region code is defined by four inputs pins of the SMPC, that are either pulled high or low via a set of eight jumpers (two per pin, one for pulling it high, another for pulling it low). With four pins, there are sixteen combinations, of which 8 were defined, but ultimately only four were used. All the Action Replay cartridges I've seen include all the original eight area codes in the header, so this effectively means that your Saturn is reporting itself as one of the eight unused regions.

Depending on the model of your mainboard, the jumpers are either traces on the board, resistors, or a combination of both. They are marked as JP6-JP13 on the mainboard. Their location varies depending on board model, but they will be near the SMPC, near the controller ports. It is unlikely that a surface mount resistor would fail silently, usually it takes mechanical damage, or a power supply problem feeding a large current through it. A PCB trace jumper is even less likely to fail, and I think you'd have noticed any gouges in the board. Nevertheless, it would be worth checking them.

For a North American Saturn, the I believe the jumpers should be set as follows:
JP6 - open
JP7 - closed
JP8 - open
JP9 - closed
JP10 - closed
JP11 - open
JP12 - open
JP13 - closed

You can also probe pins 5-8 of the SMPC, they should be pulled low, low, high, low.

Another possibility is that a memory chip has failed, corrupting the header in RAM, but I would expect the header check to fail completely in that case.