Street Fighter II missing sprites

delroy666

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Someone gave me a Street Fighter II board to try to fix. It plays fine, but it's missing all the graphics for the foreground objects (sprites). In test mode, the "Object" test shows just a solid beige screen, while the "Scroll 1/2/3" tests show all the background graphics properly. All the ROMs on the 2nd board have activity on all their pins.

In the apparent absence of schematics available for this board, does anyone here have experience working on this or similar CPS1 games who can give me some suggestions for where to start troubleshooting this?
 
Unfortunately, these games are so plentiful it would be cheaper to just buy another Sf2 pcb. I've seen people dumping these for $25-35. Typically the reason the sprites go missing is because of a bad rom or ram chip. It would be difficult without a logic probe to tell where the game went wrong. Even then, you would have to pay someone to write another rom or buy replacement ram chips or two and by then, you could find another pcb for less probably.
 
Unfortunately, these games are so plentiful it would be cheaper to just buy another Sf2 pcb. I've seen people dumping these for $25-35. Typically the reason the sprites go missing is because of a bad rom or ram chip. It would be difficult without a logic probe to tell where the game went wrong. Even then, you would have to pay someone to write another rom or buy replacement ram chips or two and by then, you could find another pcb for less probably.

I have a logic probe and multiple EPROM programmers, so that's no problem. I'm not new to PCB repair, I'm just new to CPS1 boards and was wondering if anyone had experience working on these who could give me some pointers on the architecture of the game before I dig in. e.g. which ROM contains the sprite information, etc.
 
Sounds more like a logic issue to me rather than ROM or RAM... If either of the latter were faulty you'd expect some output on the screen.
 
The Big Black chips on the top "B" board hold the grachics info.

Not sure which one has the character sprites though.

Sometimes, the graphics data is split up among two or more Big Black chips.

If your burner can read these chips, and you know whant Rom version you have, then you can check sum the chips--just don't mess the Rom legs up when you move the chips in and out of the socket.

http://www.mamedb.com/game/sf2
 
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The graphics processors are two black chips CPS-A-01 on the bottom A-board, and CPS-B-XX on the top C-board. The easiest troubleshooting step is the switch out the A-board (and C-board if the CPS-B-XX chip is compatible) from another working CPS1 game.

There are schematics for Forgotten Worlds online, which should be similar. I think you can get them here: http://ebookbrowse.com/forgotten-worlds-capcom-cps-schematics-pdf-d297812556

Like Tyranix says, the graphics are stored on the black mask roms SF2-1, SF2-2, etc.
 
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