Walt, you're right. I guess I was just too cautious and not wanting to mess up my "new" (and expensive) unit by plugging it in without protection so I figured I'd just try to test it before plugging it in. I figured I'd treat it like a circuit, assuming there'd be continuity in the GDU 375 unit between the power and ground pins.
Got a response from the G3Xperts and they pointed out that continuity between the power and ground pins would short the battery to ground. Ok, that makes sense now. Keep in mind I'm still learning wiring and circuitry (going through the Aeroelectric Connection between building), so I'm still a bit overly cautious and obviously have a lot to learn.
But sure enough, I grabbed an old 12V battery, attached a couple d-sub sockets to it and the G3X fired up with no issues, from both power source pins. I feel a bit foolish at this point, but that's how you learn right??
By the way, this is a good note to self to be careful with "ground" and the many different ways it is used.
Last edited by jMINTj : 09-14-2017 at 04:06 PM.