Electronics > Beginners
Entry level, ultra-budget oscilloscope for troubleshooting old Arcade PCBs
tsman:
Which CPS2 board is it? Has it already lost the crypto keys?
donluca:
--- Quote from: tsman on January 07, 2019, 03:59:14 pm ---Which CPS2 board is it? Has it already lost the crypto keys?
--- End quote ---
It's a Super Street Fighter II. Battery still going strong, I already have a new one ready to go in if/when I'll manage to repair it.
Don't want to derail the thread, but, to put it short, there are two separate issues: some of the sprites are shifted a tile down and the sprites flicker. The first issue is likely to happen due to an address line stuck high or low and the other one is (hopefully) caused by a buffer not working properly, likely a RAM, but I have to confirm those with the logic probe (which should arrive tomorrow). Also, due to data bus being shared between the EPROMs, it's possible that there are a couple mask roms which have gone bad. In fact, I've found that one of them has already been replaced by Capcom themselves. I'll be able to verify this once the adapter for my EPROM programmer arrives, as those are 16-bit, 42pins roms.
EDIT: here are some pics:
Have no clue about the garbage, other than it goes away as sprites get drawn over it, which reinforces my theory of a problem with a buffer.
tsman:
--- Quote from: donluca on January 07, 2019, 07:52:35 pm ---It's a Super Street Fighter II. Battery still going strong, I already have a new one ready to go in if/when I'll manage to repair it.
--- End quote ---
Nice game. No need to worry about the battery or get the decrypted ROMs. The crypto keys were bruteforced and somebody worked out the protocol needed to program the security processor. You don't need it since your battery is still okay but you can build a little Arduino based recovery device to load the necessary key back in. Good as a backup anyway.
Sorry to derail your thread more. What happens if you go into test mode? Have you checked the contacts on the ROM sockets and the interboard connectors? Any corrosion on the chips? Carefully reseated the ROMs? They're all well known to cause issues for these boards.
donluca:
I know, I actually look forward using it as a kind of clunky multi-board now that the conversion process is 100% reversible and, best of all, no need to use Phoenixed roms since I can just program the correct keys.
I'm probably going to put Progear No Arashi on it since it's a game I love and costs waaaaaaaay too much nowadays.
Also, cutting it short so I don't bore our fellow users with arcade board talk/repairs: The game plays perfectly fine and never crashes, ROM/RAM checks out all ok in test mode and I swear to god I've checked all the traces and connections and everything was fine. I even reflowed the interboard connectors just to make sure (which was 100% useless as I checked continuity, but still...). No corrosion, EPROMs reseated lots of times, also made some cross tests between my board and MAME and it looks like the culprits are EPROMs 13m and 15m, which makes them the suspect number one in my investigations.
Navigation
[0] Message Index
[*] Previous page
Go to full version