Starting a new thread on this to get some exposure on pinside. So I rebuilt the entire power chain of BH, new BRs, rebuilt main PSU board including the sound PSU, repined connectors, etc. This is for a friends machine.
His LM379S amp burnt out as the heat sink was missing. So I replaced that with another LM379S to no results, and trying the LM1875T mod yielded no sound.
I replaced all the dry capacitors on the board, but somehow I blew up the S&S board! I don't know how I did it but I did! The voltages are correct at the S&S power supply. I had the LM379S installed (being aware of pin 1 location) and installed the board. Soon as I did that within 5 seconds I lost the 5 volt and 12 volt indicators on the power supply. Nothing popped or burned as I shut it off quick enough not to cause damage. I unplugged the sound board and the game powered up fine with all the voltages present.
Put the S&S board on my computer bench power supply, and the output at R16 its repeatedly saying "FAILS, FAILS, FAILS."
I don't want to start blindly throwing parts at it. What does the error message mean? Did I blow both EPROMS? The 6502 MPU? The 6532 RIOT chip? HELP!