fusible link smoking
If it's smoking!!!! Unhook the battery!!!!
What did you have powered up?
This is either indicative of a short, a bad connection in the bulkhead connector, or the link failed and is just "finishing up" LOL
Remove the battery ground. Wire a 12V test lamp in series with the ground connection. A glow means a small current. A bright lamp means more.
Make sure the ammeter connections are "safe" and that the alternator charge wire is "safe."