My Gottlieb Alien Star stopped booting off my original mpu so I bought a replacement Swemmer board. Upon installing the Swemmer the game booted and everything seemed good for about 2-3 minutes, then I heard a snap and my displays shut off and F3 fuse blew. I replaced the fuse and disconnected the player 2,3, and 4 displays and the game came back on with the player one and credits display. This seemed fine for about another 5 minutes and I heard another snap and the displays went out again and fuse blew. This time it was when I tried putting the key in the coin door lock which makes it seem like some kind of grounding issue.
On this game I replaced the big capacitor, the 3 cabinet rectifiers, and put a new power supply board in the game. My voltages we're all good and I did all of the recommended ground mods. I wasn't experiencing any display or grounding issues with my old mpu which leads me to think that it has something to do with the new Swemmer board.-i did the ground mod for this board upon installation. Any ideas of what I should try, or what could be causing this? My power supply board has good 5,8 and 12 volts but is missing the 42 and 60 volts for the displays due to them shorting out. Could it be a bad/shorted IC on the mpu or something else? Thanks!