I recommend putting the rectifier board back in the other machine and concentrating on the original issue. The F3 fuse may be blowing due to a bad diode at locations CR5,Cr6,Cr7 and CR8. Test these diodes. The fuse F3 sole purpose is to protect the transformer from bad components.

To explain further. The diodes mentioned above rectify 14 volts AC voltage from the transformer into 12 Dc voltage that goes to the solenoid driver board and is the regulated down to 5 volts to be used for the MPU board and others. You have said that the game boots up with the rectifier board out of Embryon, so that leads me to believe that the original problem lies within the EBD rectifier board.

You could take one of the diodes out of the rectifier board from Empryon to replace the suspected bad diode. Then you would know for sure.

If I were you I would try to get the EBD rectifier board working properly and go from there. Solve one problem at a time.

Ok. touch up any questionable solder points. A shotgun approach is not necessary. The issue is the 12 volt circuit. 1 fuse and 4 diodes.