Quoted from calfdemon:
I know that you found your reset problem, but another common cause of these resets is the power fluctuation and the MPU doing a reset when it drops between 5v. I have had these issues with both my JD and SS. I will say that the daughter board created for these WPC machines solved my reset problems and I have never had another one since... best $30 I spent on those 2 machines...
I am sure you mean well and please do not take this as a personal attack.
Plugging that board in is not the correct way to fix the problem. The correct way is to diagnose it through the PinWiki page, systematically eliminating things until you narrow it down to a handful of possibilities. If you ever go to sell your games, someone else is buying your problems, and trust me, those boards may work for a while - until the 12V circuit suffers too. Then it won't matter, your games will reset even with this magic bullet, and you'll be right back at PinWiki figuring it out, only now you'll have two circuits to diagnose. I know because this happened on my TAF, and the Kahr board did NOT stop my completely and totally random reset issue.
I am all about plugging that board in to "get through" a big event like league or a big party where everyone is playing the games for 4+ hours, but I absolutely do not agree as "plug and playing" that board in and forgetting that there is a more systemic problem back there.