sugar4salt
Enthusiast
I picked up SF2 Dash for multi. Am I good to go?
- Thread starter twistedsymphony
- Start date
xodaraP
Legendary
Yes but your C board will require modification, or you could pick up one of the known compatible C boards as a replacement
Top Post Updated with nice clear pictures and simple text so hopefully we don't have any more confusion over what works or what doesn't work.
Nice and clear @twistedsymphony 
Fantastic post. I just reviewed and it's very accurate info.To Support the Multi you need 2 parts:
1. a CPS1 "A-Board" and 2. a CPS1 "C-Board"
I'm going to go through the different versions of the hardware with nice big pictures so that there is no confusion.
BEST A-Board Option:
This board has the higher MHz Clock so that newer 12MHz game run at full speed and older 10MHz games have reduced slow-down. the "Dash" Sticker identifies a 12MHz board but it's best to check the Crystal to be sure as stickers can fall off, and people can put stickers on boards that shouldn't have them.
GOOD A-Board Option:
This board is identical to the "Best" Option except that is has a slower 10MHz Clock. Games will work but they may suffer slow-downs. Some people have "Upgraded" these boards by replacing this 10MHz Crystal with a 12MHz Crystal. The Nuances of this are discussed in other threads such as this one: https://www.arcade-projects.com/thr...rystal-oscillator-to-upgrade-an-a-board.5721/
BAD (Unsupported) A-Boards:
The Multi does not support Long boards. The older CPS1 games came on the "Long board" identified by it's added length, but also from it's different dip switch and audio amp configuration.
Boards that are missing dip switches and Audio Amp are also not supported. These were the A-Boards used in "CPS Q-Sound" Games, aka "CPS1.5". Obviously the problem here is that you will be missing audio if you use one of these boards.
Some dubious e-Bay sellers have taken some of these boards and added back in the Dip-Switches and low-quailty audio components. These are easily identified by the crappy looking audio amp setup as seen in the photo below:
These may work, however it is not recommended and reports are that the audio quality is quite bad due to the shortcuts taken in rebuilding the audio section.
Use at your own Risk.
BEST C-Board Options:
Unmodified 92641C-1
*note that this has a battery and that there are no solder jumps, cut traces, or bodge wires indicating a modification
Unmodified 90631C-5
*note that this has a battery and that there are no solder jumps, cut traces, or bodge wires indicating a modification
*Some variations may come with a black cover over the board
These options are the best because they they allow key-re-writing which means that they can support encrypted ROM sets as-well-as decrypted ROM sets, giving you the most flexibility.
GOOD C-Board Options:
Modified 92641C-1
*note the lack of battery and the bodge wire connected to the CPS-B-21 Chip, as well as Cut Traces and Jumped Pins
Modified 90631C-5
*note the lack of battery and the bodge wire connected to the CPS-B-21 Chip, as well as Cut Traces and Jumped Pins
92631C-6
These "Good" Options will work, however you will be limited to only using "decrypted" ROM sets.
It's possible that the "Modified" options above can be "un-modified" to return them to their original key-writing function (allowing you to play encrypted ROMs).
Similarly the 92631C-6 can potentially be modified to support key-writing (allowing you to play encrypted ROMs). For More Information See this thread: https://www.arcade-projects.com/thr...a-90631c-5-battery-backed-b-21-c-board.13116/
BAD (Unsupported) C-Boards:
Any C-Board not listed above
Any C-Board that does not include a "CPS-B-21" labeled chip is not supported by the Multi. The only Official C-Boards that include the B-21 chip are those listed in the "Best" and "Good" Options above.
Some people have made custom C-Boards using "CPS-B-21" chips, these may or may not work, use at your own risk.
What Donors To look for?
Unfortunately A lot of CPS1 games have components mixed and matched with each other, even back in the day Arcade Operators and even Capcom themselves would swap parts to make working sets. Today it's even worse with "De-Suicided" boards and conversions vastly outnumbering original matched board sets. With that Said most conversions used the "CPS-B-21" based C-Board variants found in the "Good" category above, and so long as they're matched with a "Good" A-Board Variant it should make a suitable donor. If you do want to try your luck finding original, unmodified, non-conversion CPS1 board sets for the "Best" possible donor (12MHz A-Board, and C-Board Capable of Key-rewriting and encrypted ROMs) then these are the games:
- Capcom World 2: Adventure Quiz
- Captain Commando
- Knights of the Round
- Quiz and Dragons: Capcom Quiz Game
- The King of Dragons
- Three Wonders
- Varth: Operation Thunderstorm (Japanese Version)
Photo Credits: Many of the great photos in this post were taken from mvs-scans.com, a great resource! Also thank you to xodaraP for the Q-Sound A-Board photo. The rest of the photos were found on various forum posts and ebay listings.
mathewbeall
Champion
You can usually undo the mod fairly easily. I bought 2x modified c-boards and was able to reverse the modification on both of them without much trouble.
I believe @sheep_nova also sells unmodified c-boards for a reasonable price as well.
mathewbeall
Champion
Is it more than just removing that wire and cleaning up the solder bridge on the chip?
Yes But not much.
The Old C-Board De-Suicide Method:
CPS-B-21 Pins 45 and 46 are normally connected to ground. The old "de-suicide" method was to disconnect these pins from ground (on some chips this was done with a trace cut, on others they lifted pins where there were traces under the chip). After disconnecting from ground these pins were then tied to +5V.
Undoing the modification:
To reverse the mod you simply need to disconnect these pins from +5V and then re-connect them to Ground.
- Start by removing the bodge wire
- If the pins are lifted then solder them back down in place.
- Use a Multi-Meter to check and make sure there is no lingering continuity between the pins and +5V
- Connect Pins 45 and 46 to ground. If the pins were lifted then you might already be done. On some boards this might be just adding a solder jumper to the nearest ground pin, on other boards you might need to add a new bodge wire to tie the pins to ground to "fix" any cut traces.
- Do a final check to make sure there is no continuity between +5V and Ground
Testing That you were successful:
If you have a CPS1 C-Board Infinity Key you can easily set the jumpers to whatever game you're trying to run, then plop that on there, and if it boots/plays you've confirm functionality.
Alternatively you can re-install a battery and then use the Arcade Hacker's Key Restore method to reprogram the original keys. and if that boots/plays you've confirmed functionality.
Obviously once you've got the multi in-hand you can also use the multi to confirm that it's done right, however I would recommend waiting until you've got the Multi setup and running on modified C-Board first, so that you know the A-Board and multi are functioning properly before you undo the modification, that way you aren't trying to trouble shoot multiple things at a time.
Great post @twistedsymphony
mathewbeall
Champion
Esoteric_rt
Student
So you cannot use a 'long' A board - is that the final decision on this, or still being worked through?
All I have is a long A board...
All I have is a long A board...
It really feels like Groundhog Day around here sometimes.
@twistedsymphony Just for completeness, there is also another "Best C Board" option, the one used originally at Three Wonders pcb stack. It is the "90630C-4", it's similar to "92641C-1" in term of capabilities, but slighty different component organization.
It could be modified to run decrypted roms. In that case, it should be also de-modified to run the complete cps1 romset as you stated in the first post.
It could be modified to run decrypted roms. In that case, it should be also de-modified to run the complete cps1 romset as you stated in the first post.
Thank you! I was not aware of that C-Board. The Top Post has been updated.
If you come across any photos of the other side of the PCB please let me know.
