I've had this Mortal Kombat 4 board that worked fine like 15 years ago. For the longest time it was stored and didn't move at all. About 2 years ago I pulled all my boards out of storage and installed a JAMMA switcher in my cabinet. Every other board worked right away , but MK4 no longer did. It turns on with solid LEDs and that's it. I've tested all the ROMs by dumping them and comparing them to ROMs available online, all were fine. I erased them all and updated to revision 3.0 but still nothing. I know this is a shot in the dark because all the research I've ever done on this issue yield nothing.. Every one seems to say that solid LEDs = dead board. Surely with all the knowledge and advance in technology since the manufacturing on these Zeus boards, something has come out as to why this is happening? There are no leaking caps , I've tested pretty much every passive component on the board, remove some logic chips to test them out of the board but I can't find nothing. I tried tracing a whole bunch of lines to RAM , ROM , CPU etc and didn't find a single break anywhere. The board is WARPED though .. I would really really love to get this board back in working condition so that my cabinet has all 4 Mortal Kombat games running. I've check all voltages and they are within spec (-5v included). Is there anyone with more knowledge on this board? Schematic ? Boot sequence? Can anything be found about the boot sequence from how MAME runs the game? I have a logic probe , oscilloscope , multimeter , hot air station, soldering iron, QG-4x to read the roms, including the adapter to read/write the bigger roms found on this board. The board is clean with no visibile trace damage, but it is warped although only slightly. The rom chips currently don't have labels , but I'm 100% of each of them's integrity as I have tested and reflashed all of them in the past months and nothing in the behavior of the board as changed after that. Is there a test rom or a modded security chip that can be used to try and bypass booting errors?
I will focus on that crystal and dipswitch for now.