I was having boot issues with my Swemmer sys80 board in my Excalibur (another issue, another thread), so I put the original board back in. There wasn't anything wrong with it; I was just trying to track an especially pesky issue when I bought the machine, and so I bought an mpu. It worked fine until a few weeks ago, and then refused to boot... anyway... I put the original back in and it boots just fine and goes into attract mode. I can credit it up. And then I start a game...
Boy Howdy! The reset coils for the drop banks and the coils for the two lock/kickout hole start firing in rhythm, kakakchunk, kakchunk, kakachunk, chunk chunk, over and over! It literally sounds like galloping horse. It keeps going until you hit the first scoring switch on the playfield. The the coils stop firing, and the game plays and scores normally, including sounds. But then! You shoot the ramp, and it begins again! Only this time the rhythm is different; it still sounds like a galloping horse (the insert lights are even synched to the rhythm of the coils firing--or more likely vice-versa), and then it stops when the ball lands in the lock/kickout hole.
It all starts over with ball 2. As i said, the game plays and score normally, including sounds. It's sorta, kinda kewl, but not really, and I can't make it stop!