What is the make/model of the power center? If it has both 120v breakers & 12v fuses in one panel, odds are the converter/charger is integrated with it.
Another way to find it is to start at the batteries and follow the big positive cable back to it. Usually isn't far either.
Here's a
previous thread where the owner of an Alfa 38 ft 5W mentions his converter location.
Also, what year Alfa Gold 5W?