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Seibu Kaihatsu SPI Motherboard Log

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Symptom: Every game inserted throws up a checksum error


Solution: Seibu SPI boards are kind of a pain in the neck in that every time you plug a new game into them you need to let the board copy data from the cart to the on board flash roms which takes about 10-15 minutes.


If you interrupt this process, you have a problem since these flash ROMs hold the region code of the board in the first byte of flash and this gets erased before setting it again.. except it sets this LAST. This is why the checksum error occurs since the region will be incorrect, no matter what game you plug in.


The way to restore these boards is to remove the program rom at location u211 on the cart PCB and make a note of what the last byte is in the file. Alternatively you can load up this file from the MAME romset in a hex editor and check it there. Next you need to remove the TSOP 40 28F800 flash ROM at location u1053 on the motherboard and dump the contents of the flash, change the FIRST byte to the same as the last byte in the program ROM and reflash it to the IC, then solder it back to the motherboard.


Presto, you should now be able to set JP1 and write the flash of your favorite game knowing NOT to interrupt it again!

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  • 10 years later...

Lots and lots of bad solder joints on the SPI surface mount customs... Start there with reflowing. If you don't know how, send it to Womble.


Also, since this thread was bumped... you don't always have to remove the Flash ROM now if the region byte was corrupted... There's a program to help with that but it's not supported on all game carts.





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