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DARKSOFT What Donor Board to use for the CPS1 Multi

That is an answer for @Kujako and anyone who doesnt have a original unmodified C Board. We strongly recommend to use unmodified C Board from the type indicated in the instructions.

Each game uses a different B-XX chip on the C Board. The B-21 can be reprogrammed using the method that ArcadeHacker explained, so that they will behave like any other B-XX chip.

In order to have the B-21 programmed you need access to the pins that I specified above. Check the github for more info. If you are not able to program the B21 as something else, you wont be able to play any other game.
 
Just looking for some help please ive just been notified my multi has been shipped I have an unmodified 92641C-1 with battery (purchased from sheep nova) as per the photo on the first page of this thread that apparently is the best C board option that allows key writing but reading the new install instructions it says the battery has to be removed, I'm confused can I keep the battery or does it need to be removed?
 
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Swisstoni69 said:
Just looking for some help please ive just been notified my multi has been shipped I have an unmodified 92641C-1 with battery (purchased from sheep nova) as per the photo on the first page of this thread that apparently is the best C board option that allows key writing but reading the new install instructions it says the battery has to be removed, I'm confused can I keep the battery or does it need to be removed?
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Remove it. It doesnt make sense to keep a battery that can leak on such a nice system.
 
Darksoft said:
Those C Boards dont look like they had a good job done on them. You might be shortcutting some signals without even noticing it.
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Agreed, but one goes into battle with the 'C' boards you have, not with the 'C' boards you want. Long term I'll keep looking for a better one. I do have a stock one on hand, but it's ion an original SF2 set I don't want to break up.

Of the two, the second (yellow dot) is closest to stock that I think I can restore it well enough (it's the same modification seen elsewhere in this thread). I'm just really baffled by the state of the other and trying to figure out why 41-44 are bridged in this manor. The bodge wire is also going to a location I've not seen used before.
 
As I posted before pins 42 and 44 should be connected to the C board connector, not to GND. Like that you won't be able to play any game, except this that work in B21 Default mode.
 
Darksoft said:
As I posted before pins 42 and 44 should be connected to the C board connector, not to GND. Like that you won't be able to play any game, except this that work in B21 Default mode.
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Then I'll put this one into the pile of unknown monstrosities. Still curious as to why what was done was done, and given some spare time I'll see if I can "fix" it back into a more standard configuration. For today I've reverted the modification on the other *yellow tag without battery*. Bridging the two cut traces to the next one over (also ground) and running a new bodge wire. Checked with the multimeter and all looks good. Means I have to replace this one at some point, but it was on a Three Wonders bootleg "B" board so not sure how much I care... perhaps I'll try to get the other with the weird bridged pins to work on the Three Wonders board.

Quick Camera Image 2022-05-28 at 10.05.41 AM.png
Quick Camera Image 2022-05-28 at 10.10.56 AM.png
 
I've been practicing my n00b soldering on my F3 and ST-V and am finally getting around to my CPS-1.

My 92641C-1's no-battery mod bodge looks a bit different than the one twistedsymphony described in the OP. It looks like traces were cut for pins 43, 45, 46, and 47. 45 & 46 were attached to this resistor at D2 (does that provide +5V?). Do I just need to reattached 45 & 46 to ground at pin 40 or 41, or also do something for 43 and 47? Since it has no battery, does that mean I have to do this more complicated set of changes mentioned in the OP?
CPS-1 C-board original bodge.jpg
 
@Ikaru that’s right. It’s spelled out clearly in the user guide as well as that thread.
 
Can I get confirmation this C board is good to go? I was told this is multi ready but before I connect it I would just like the official thumbs up from the board here.
20220805_145659~2.jpg20220805_145710~2.jpg20220805_145733.jpg
 
The watch battery should be removed. Otherwise as long as the solder joints in the lower-left corner of the chip are applied correctly then you should be good to go. A closeup picture of the lower-left corner of the chip would be helpful.
 
ShootTheCore said:
The watch battery should be removed. Otherwise as long as the solder joints in the lower-left corner of the chip are applied correctly then you should be good to go. A closeup picture of the lower-left corner of the chip would be helpful.
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Doesn't the battery allow for the use of encrypted roms or am I mixing something up?
 
The battery holds the keys but you don’t need that, the multi kit will inject the keys on boot same as CPS2

Remove the battery and that C board is good to go
 
SubScorpion said:
Doesn't the battery allow for the use of encrypted roms or am I mixing something up?
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No, the Multi writes the decryption keys to the C board every time you power up or change games. If the battery is present then the C board only retains one key and it gets in the way of the Multi changing the keys.
 
ShootTheCore said:
No, the Multi writes the decryption keys to the C board every time you power up or change games. If the battery is present then the C board only retains one key and it gets in the way of the Multi changing the keys.
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Ah got it. So what's required for the use of encrypted roms? I'm a little confused.
 
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