I recently put out a call for some CPS2 B Boards that were battery damaged, and I've received 2 so far. The first one I received is the one I've done the most work to so far. Here's what it looked like when I received it.
As you can see it was in rough shape. My first course of action was to try removing enough of the corrosion from the DL-1927 chip that I could try to remove the chip from the board and inspect the traces underneath it. I brushed the traces with a fiberglass pen and an X-acto knife until I could reveal some of the remaining solder. I carefully reflowed the solder on the pins that were still present on the chip until I felt confident that I could remove the chip with my hot air rework station without damaging the pads. After removing the chip and fully cleaning and tinning the pads, I found many breaks in the traces below the chip. I set to repairing each one of them using 32AWG enameled wire.
I then dremmeled and dug out the traces for the missing legs on the DL-1927.
I soldered the DL-1927 back to the board and wired the missing legs individually to the board.
After that I put a set of Street Fighter Alpha 2 roms that I pulled from the second dead B board that I received, attached it to an A board and fired it up. I wrote the proper keys for SFA2 but I got a solid color screen and no signs of life from the B board. After this was a long process of probing each and every pin on all of the customs with my oscilloscope to check for activity and cross reference it with the CPS2 B board wiring spreadsheet. I found many broken traces between the graphics roms and the custom ICs as well as several broken traces between the various ICs. I repaired each and every one that I could find. Probably 30-40 in total.
So now we arrive at the current status of this board, and where I need some advice. The board boots now to a white screen, however it is not a suicide screen, the game actually works. Audio is working correctly and the game plays through it's attract mode correctly. Inputs are working properly, but I only get a white screen for graphics. Occasionally I have been able to get small amounts of garbled graphics on screen when probing around the 74LS245s at 10L and 10M, but this behavior can't be replicated consistently.
View: https://youtu.be/c7_slnWCK3U
As far as I can tell there are no remaining broken traces, so my question at this point is which custom is most likely responsible for my lack of graphics, and does anyone have any ideas as to where I should be looking diagnostically to track down the source of this problem. At this point I have exhausted all of the diagnostic options that I can think of, and with the CPS2 being so poorly documented any help that someone with more specific knowledge of the hardware could provide would be much appreciated.
As you can see it was in rough shape. My first course of action was to try removing enough of the corrosion from the DL-1927 chip that I could try to remove the chip from the board and inspect the traces underneath it. I brushed the traces with a fiberglass pen and an X-acto knife until I could reveal some of the remaining solder. I carefully reflowed the solder on the pins that were still present on the chip until I felt confident that I could remove the chip with my hot air rework station without damaging the pads. After removing the chip and fully cleaning and tinning the pads, I found many breaks in the traces below the chip. I set to repairing each one of them using 32AWG enameled wire.
I then dremmeled and dug out the traces for the missing legs on the DL-1927.
I soldered the DL-1927 back to the board and wired the missing legs individually to the board.
After that I put a set of Street Fighter Alpha 2 roms that I pulled from the second dead B board that I received, attached it to an A board and fired it up. I wrote the proper keys for SFA2 but I got a solid color screen and no signs of life from the B board. After this was a long process of probing each and every pin on all of the customs with my oscilloscope to check for activity and cross reference it with the CPS2 B board wiring spreadsheet. I found many broken traces between the graphics roms and the custom ICs as well as several broken traces between the various ICs. I repaired each and every one that I could find. Probably 30-40 in total.
So now we arrive at the current status of this board, and where I need some advice. The board boots now to a white screen, however it is not a suicide screen, the game actually works. Audio is working correctly and the game plays through it's attract mode correctly. Inputs are working properly, but I only get a white screen for graphics. Occasionally I have been able to get small amounts of garbled graphics on screen when probing around the 74LS245s at 10L and 10M, but this behavior can't be replicated consistently.
As far as I can tell there are no remaining broken traces, so my question at this point is which custom is most likely responsible for my lack of graphics, and does anyone have any ideas as to where I should be looking diagnostically to track down the source of this problem. At this point I have exhausted all of the diagnostic options that I can think of, and with the CPS2 being so poorly documented any help that someone with more specific knowledge of the hardware could provide would be much appreciated.
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!!!!!
