Help with a SMS/Genesis Cartmod. Phantasy Star Retranslation

[TheDoug]

Hi, I want to play Phantasy Star 1, and I have the cartridge Phantasy Star 1 Fukkokuban for Sega Mega Drive.
This game is just the Master System game inside of a Mega Drive cartridge.
There is a PS1 retranslation (http://www.smspower.org/forums/viewtopic.php?t=9492), so I want to do this cartmod.

There is little information about Master System cartmods, but seems to be easy.
Seems that a 27c4001 matchs exactly the SMS mask rom when there is a Mapper chip inside the cartridge (based on this doc: http://www.consolasparasiempre.net/doc/SMSPinRom.txt).

So, here is my cartmod:





But this is not working. I get only a black screen.

Maybe I need to change some pins, but there is very little information about SMS cartridges.

Any ideas to help me?

Thanks.....

[PigInTheMud]

Do you know the number for the ic chip that was removed and for the one that you put on? There could be some pinout differences.

[Ziggy]

Have your verified the pinouts? Find the pinout for the cart edge connector. Grab the datasheet for the EPROM you're using. Use a continuity meter to check that each pin on the cart edge connector is going to the appropriate pin on the EPROM.

Failing that, check the EPROM on another SMS cart.

This is, of course, all assuming that the hack will work on real hardware. Has the hack been confirmed as working on real hardware? There could be a fatal bug that causes it not to boot or to lock up right away. Checking it on a flash cart would help.

edit: Verifying the pinout (EPROM vs cart edge connector) will be the best first step IMO. If there's a difference in the EPROM pinout compared to the socket, this is how you'll find out. If it turns out to match, then you'll know to start looking for other problems.

Checking the EPROM on another SMS cart would tell a lot as well. You're taking a few things out of the equation. If you try this, put the EPROM on a cart that doesn't use SRAM. If the game boots, at least you've ruled a few things out.

Do you know the number for the ic chip that was removed and for the one that you put on? There could be some pinout differences.

Mask ROMs don't usually have the actual part number on them. Like, if it's a 4Mb mask ROM, it's not gonna say "27C040" on it.