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MVC2 Cart ROM Board Test

mR_CaESaR

mR_CaESaR

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Hey guys,

Just a quick question.

I've got a couple of MVC2 carts that Ken fixed for me a couple of years back

1733979210002.png


I'm looking at selling one now (the one that wasn't a transplant). As I went into the ROM test, I just get a blank screen like below, no matter which BIOS I use.

1733979287048.png


The game works perfectly fine

1733979340674.png


Could it be because I have the "unlocked characters" EPROM on IC22? I don't have the original EPROM so I'm not sure if that's the issue. This happens on both carts that Ken fixed for me.

For my cart, I couldn't care less as I know it works, I just know there might be some concerns with others that may want to purchase the cart.

Anyone ever come across this before on their MVC2 cart?

Thanks in advance
 
Rom board test definitely works with the unlocked characters eprom.

Not sure what's going on with your cart.
 
Thanks. I didn't think it looked right.

Must be something to do with the repair as both carts show the same behaviour.

I guess it somewhat devalues the cart? Maybe it might not be worth selling :(
 
It's not a problem unlocking the eprom, most likely it's because your ROM board hasn't been completely fixed
 
zyl501zyl said:
It's not a problem unlocking the eprom, most likely it's because your ROM board hasn't been completely fixed
Click to expand...
I think it's more about the checksums of the roms. I trust that Ken from irepairsega repaired the cart as best as possible. Everything on the cart works except the rom board memory test. Ahh well.
 
I have encountered this problem before, and I dismantled IC30 and IC29 to solve it.
 
mR_CaESaR said:
Anyone ever come across this before on their MVC2 cart?
Click to expand...
which type is your MvC2 cart(s) ? there exists 2 PCB types. it would be nice to see PCB photo
does your games have "rom board test" option in game test mode?
which BIOS version is in your Naomi ?

in general, I'd imagine your cart is 171-7978B (Actel) type, but currently it have program EEPROM from 171-7919A cart version. or something like that.
 
MetalliC said:
which type is your MvC2 cart(s) ? there exists 2 PCB types. it would be nice to see PCB photo
Click to expand...

This particular one I'm looking at selling is a 171-7978B





The cart that Ken "transplanted" is the same, but it doesn't have that jumper wire.

MetalliC said:
does your games have "rom board test" option in game test mode?
Click to expand...

Yeah it does



MetalliC said:
which BIOS version is in your Naomi ?
Click to expand...

It's using the multibios from mathieulh with it set to Euro atm.

https://www.arcade-projects.com/threads/naomi-multi-bios-fixed-with-proper-bootstrap.14842/

MetalliC said:
in general, I'd imagine your cart is 171-7978B (Actel) type, but currently it have program EEPROM from 171-7919A cart version. or something like that.
Click to expand...

I would've thought this could've happened with the cart Ken "transplanted" but he only did one as he was able to fix the other cart, but since both carts exhibit the same issue, I thought it may have been the eprom. I mean I've played the game through and it all works as expected, I just think potential buyers would want to see the rom test board screen be "OK" if I was to sell the carts.
 
MetalliC said:
thanks, this is indeed original MvC2 PCB, Actel type, with original for this game Actel FPGA


no, I meant go to GAME TEST MODE at your photo, and check if it have "ROM BOARD TEST" option
Click to expand...
The only thing in the GAME TEST MODE is

INPUT TEST
GAME DATA
GAME CONFIGURATION
EXIT
 
@mR_CaESaR then my 1st guess was right - program EEPROM in your cart programmed with MvC2 version for 171-7919A type cartridges, which don't have ROMs checksums for Actel-type cart in game header (as result you see empty ROM TEST screen in BIOS) and missing "ROM BOARD TEST" option in game test mode.

I'd say it may be ignored, if your game works fine
 
it may not work after this. I suppose there was a reason why cart was programmed with this ROM (something broken in protection/decryption part?)

however it may be not bad idea to read program EPROM, "paste" to game header checksums for Actel-type carts and program it back.
I may provide checksums and instructions for you, or paste them by myself if you'll dump your ROM and share data.

PS: strictly speaking, I suppose it's kind of my fault :D I've did protection hack of MvC2 171-7919A type couple years ago, mainly to help "fix" cartridges with something broken in protection part, but I've not expected it may be used in Actel-type carts :)
 
Last edited:
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I was talking about reading EPROM which is in your cartridge, socketed one, then edit data adding checksums to game header area, and them program to another or same EPROM
this way you'll get at least BIOS ROM TEST list with some ROMs on screen

it's also not ic22 but ic11 in this type carts ;)
 
MetalliC said:
then try this https://mega.nz/file/gAFHGJrZ#fEmZKXzFK-qEA_EWm7WXSHTB72w31KQUavMkBx-UVWM
Click to expand...

THANK YOU SO MUCH!!

Burnt on a 27c322 and I can report the following:

On export or US bios selected (on multi bios), I now get the rom board test





Unlocked characters only appear when US bios is being used (I think that's how it was with the other eprom I had).

US Bios



Export Bios



ROM BOARD TEST MODE still doesn't appear in GAME TEST MODE (not sure if it's required as the ROM board test is now working



Thank you so much @MetalliC - low key, I was hoping you'd know the answer and you did! Once again, thank you so much!
 
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