That is great to hear. Not surprising considering what I've seen of Namco's SMD caps. It seems like any time problems with System 11/12 turn up, we should start with a recap to be safe.I also has experienced same symptom. turns out my sys12 has been converted from other one and rom board caps are failed. after recapping rom board it came alive.
That is an awesome deal and if I were a betting man, I'd always place my bets on bad caps if it's an 11/12. You should have them back in action in no time.
Ok so I can't, then, take a Soul Calibur base board and throw on a Tekken Tag rom board, and expect it to work? They both show up in MAME as a "System 12 Mother (B)" but I haven't been able to get any results swapping with known CPU boards. I just assumed that meant the ROM board was bad.The two flash chips on the bottom board generally got corrupted/erased/busted on these PCBs. These flash chips carry the program code. I've fixed a few of these boards and most common cause of the problem (especially if it partially boots) is fixed by re-flashing these.
Having a working spare around helps alot to check if the ROM boards are fine.
ROM boards are not interchangeable but CPU boards (top board) are.
The game specific code resides on the bottom board, two flash chips carry the program code and one obscure flash chip (never found a programming adapter) carry the sound samples.