Change your caps! The capacitors in your games can be several decades old. Remember, when in doubt, throw it out. I recommend investing in an inexpensive ESR meter so you can test caps before changing them to help pinpoint problems.
Someone rebuilt the power supply in this Zaccaria Farfalla and the game wouldn’t start, after several board changes including a different power supply and a brand new logic board, it still wouldn’t start. The game worked fine before rebuilding the power supply. It’s always fun figuring out a problem when multiple hands have been involved.
There’s a power failure circuit on the power supply and if it’s faulty it can prevent the logic board from coming out of reset. All voltages were present so I knew there wasn’t a failure.
It’s a simple circuit made up of an LM339, some transistors and a few other passive components, including a 1uf radial aluminum electrolytic capacitor.
To keep it simple I changed the cap without doing any other diagnosis. All of the other caps on the power supply were changed except for this one. For the first time in almost a year this game is showing signs of life.
Always keep it simple and look for basic things first.
More to come on this Farfalla…..