I'm working on a Williams 40X Jackpot Party. It was completely dead when I first looked at it. Both upper and lower power supplies were dead. When I looked at the I/O board, only the rightmost LED +18 was lit. I replaced both power supplies and now it powers up, all the LED's on the I/O board are lit up (+5,+12,-12,+5,+18). I get one bong when it powers up, the upper display show "Williams" on it. It shows numbers in the credits and payout displays, however, it does nothing when you press the panel buttons, reset button, turn the momentary key switch on the right side of the machine.
Question...
Are all the LED's on the I/O board supposed to stay on? From what I've gathered, that may not be normal?
I've checked the cable from the door to the back plane and the cables from the front panel to the back plane. They all checked out fine. Is it possible that I have a bad I/O board?