A mate of mine got hold of a Warriors of Fate CPS1 (actually 1.5 due to Q sound) PCB. Not knowing much about them apart from the fact that it was a Capcom board he threw some $$$ at it not knowing that this board contains suicide batteries. These are batteries that keep some PCBs alive by maintaining power a decryption table. This is required to decrypt encrypted program ROMs. Once the battery can no longer provide power to maintain the table, the code on the ROMs can no longer decrypted, and the game will no longer work. There are a number of Capcom and Sega boards in particular that work like this. Lucky for my mate this issue can be fixed using decrypted ROMs, and I have the tools to do it. Note the following details are specific to Warriors of Fate.
As you have probably guessed, the board no longer worked due to the batteries no longer providing enough power to maintain the decryption tables. The fix for this problem is well documented. A good place to start is http://www.arcadecollecting.com/dead/. This site provides all the details you need, along with links to unencrypted ROM sets.
After downloading the relevant ROM set from the above resource, time to get to work.
On top of the board there are 4 plastic caps covering screw holes. gently prise these up, including the one under the warranty sticker. Use a phillips head screwdriver to remove these top screws.
At the front of the board, remove all 7 screws/ It is likely you need to use a torque screwdriver for these screws.
Before attempting to remove the top cover ensure you have removed the 3 screws along the top at least. When removing the top cover you will need to use some firm controlled force. Get your fingers under a top corner and pull. Be careful as the fan is connected between the top cover and the Q Sound board as pictured.
This will expose the inner PCBs. The small top board in the stack called the C Board. Carefully prise this off, again firmly and controlled. On the top we have the first suicide battery. Carefully remove this by desoldering the connections.
Now flip the board over. Time to do some fiddly work an a big SMD chip. Locate pins 45 and 46 on the CPS-B-21 chip. Open the second image below for a close up. Carefully cut the traces going to ground for pins 45 and 46, not damaging any other traces. Ensure you have fully cut the traces by measuring resistance between the pins and ground. Add solder to these 2 points (bridge them together) then run a wire to a 5V source. I chose a point on diode D1 as per the 3rd picture below.
Now a ROM on the B Board needs to be replaced. Chip 23c needs to be removed. Either erase and reprogram the chip withe 2 unencryprted code from http://www.arcadecollecting.com/dead/, or get a fresh 27C4096 chip to program. Skipping ahead (still have the Q sound board fix to go) for some reason on this board although it had european ROMs, I found they didn’t work (blank screen on power up). So I burned the unencrypted US set for chip 23 and the US version of chip 22 and found that it worked. I don’t why the board had this problem.
These boards also have another suicide battery on the Q Sound board, which is sandwiched between the A Board (bottom) and the B board. To get to the Q sound board, carefully ease the front edge connector set off, then remove the B Board and Q sound board from the stack using firm controlled pressure. I had already removed the suicide battery before I took the photo. See on the second picture below, right hand side for where the axial 1/2AA battery is situated. Carefully desolder the battery..
Next resistor at R33 and capacitor at C12 need to be removed. In the first picture below the smd resistor and capacitor have been removed. Now bridge where C12 was as shown in the 2nd picture.
Next an unencrypted ROM for the Q sound board is needed. A 27C020 eprom is required, burned with the relevant binary file from http://www.arcadecollecting.com/dead/cps-q.html. Remove the existing ROM and replace in the below picture.
Last thing to do is now turn the Q sound board over. Cut the trace from pin 30 of the 27C020 to pins 31 & 32 as per the first picture below. Then solder a wire from pin 27 of the Kabuki to pin 30 of the 27C020 as per the second picture below. The Kabuki is conveniently named on the chip itself topside 🙂
Last of all, put all back together and if you have done everything correctly it should work. It should be noted that often A boards develop faults with the SMD CPU, so just hope that the A board works when you desuicide boards like these.
If the battery on the “C” board dies on any of these games, the game can be revived by modifying the c-board to be reset it to it’s default, battery-less settings and patching the game’s program ROMs to use these default valu