My Robocop has developed some strange issues with how it is acting. If you are familiar with Robocop I can get detailed with what is happening but for now I'll describe it in generic terms.
The behavior is not consistent. I can turn on the pin and play a few games and I will be dealing with something happening when it should not, or something not happening when it should. I can turn off the pin and come back later and the first issue has gone away and something new starts happening. And I am wanting to find out if there is some sort of logic IC on the CPU has gone bad.
1) For a few games, after the game was over I would be prompted to add my initials for a new high score. But there was no high score. Sometimes I would be prompted to initial a high score 7-8-9 times in a row. That behavior has stopped.
2) Sometimes an inlane rollover will not score after I shoot a ball. But after the ball has entered the play field and hit a couple of play field switches and I manage to get the ball back up to the top and go over that inlane rollover switch again, it will work properly. When the ball drains and I launch the next ball the behavior returns and that rollover will not work until the ball hit a couple of switches; When I get the ball back up to the top the rollover will work as is it supposed to.
3) I have the same issue with the return lanes. The first time a ball enters a return lane I get nothing; The next time through, the return will act as it should. But the outlanes always work.
4) One time when I had a multi-ball going, I got a multi-ball Jackpot bonus. However, I had not even come close to making the shot required to activate the Jackpot bonus. I was just given a spontaneous Jackpot "gift".
5) And yesterday afternoon, I turn the pin on and 3 major functions of the pin were not working correctly. Last night when I started the pin up to play this issue had gone away. This morning the issue had returned again.
6) This pin is like a lot of Williams in that it has a lot of double switches where the 2nd switch activates what are called "Turbo sounds". The pops, slingshots, and flippers all have the Turbo sounds. The Turbo sounds come and go. Sometimes the flippers have the Turbo sounds and sometimes they do not. Same with the slingshot Turbo sounds. With the pops, the ball can be bouncing around between all 3 pops and the Turbo sounds can be on or off several times while the ball is bouncing around between them.
7) Recently, if I hit a couple of game scoring options in quick succession, all of the feature lights freeze up. The game will still play but the feature lights stay frozen for 5 or 6 seconds before they start working again.
I can run through the switch test, the All lamp test, and individual lamps tests with the coin door switches. Everything tests OK; I don't get any error messages.
I have reseated all of the connectors in the back box, cleaned the sound cable at both ends. I was having some crackling sounds coming from the speakers but I cleaned up the sound potentiometer and all of my sounds are crisp and clear.
The game plays well and everything is doing what it is supposed to do mechanically.
I have a Hakko desolder gun and the soldering equipment so I can replace what needs replaced. I just don't know how to trouble shoot this.
Any thoughts and ideas are appreciated.