1972 410 Commander Alternator question

Hello, looking for assistance on identifying a charging issue on one of my 427's (1972 410 Commander). The port engine was charging then it stopped charging causing the engine to stop running, assuming because of low voltage to the coil, but after a few minutes of stabilizing, the engine will start back up and run for awhile longer until it dies again. I had the alternator checked and at first the tech said it was overcharging because the internal regulator may have failed, so he cleaned it up and changed out the magnets inside the regulator and showed me that the alternator was now working. It may have been working all along. He also said to make sure the voltage supplied to the alternator from the ignition had 12 volts. That I didn't check until after I reinstalled it and there is no voltage to the alternator. I'm wondering if anyone knows if there may be a fuse somewhere for that supply? The tech said check for a fuse but I have not idea if one exists and haven't found one yet. I have continuity from the alternator to the harness connection next to the engine (orange wire) but I haven't traced it any further. The alternators I have are Motorola with with a Motorola external voltage regulator feeding the coil. Only 10 volt goes to the coil when running, and no voltage generated to battery. My limited understanding is suggesting to me that these alternators need 12 volts supplied to it in order to what, excite it? Can I jump in another 12 volt supply to it separate from the ignition if I can't find the issue? My wiring inside my consul is all original and I hate to go inside to check things as I tend to make matters worse. One more piece of the puzzle is I may have caused this by installing a Smart battery switch between this starting battery and the house batteries as I noticed that my house batteries were not being charged while the engines were running. It was working when I installed it and tested it but it wasn't long before the alternator stopped charging. I have since disconnected this Smart switch but maybe this caused this issue.

Any help is greatly appreciated.

Regards,

Jeff Bentley