There could be a fuse, then again there may not, it depends on the person who wired the system. A seatch of the SeaTalk
cabling should not take too long. The only other fuse in a SeaTalk
system I am aware of would be in the autopilot
, but as you have a Robertson unit we can exclude that.
You will have to take a methodical approach to trouble-shooting to determin where the power originally was sourced. Of course, you could also introduce an alternate 12V supply to the SeaTalk system.