1. There is no such thing as a DC neutral buss.
2. If outside the box, it is usually the GROUND/Negative BUSS for the 12 volt DC appliances and connection from the Chassis frame ground
3. The wire(Black) that has the 2 wires soldered together, that is the HOT 120 wire that comes from the CONVERTER to the 120 breaker in the breaker box. The soldered end is installed in the breaker(15 or 20 amp) and the Black loose pigtail is wire nutted to a 120 appliance or 120 wall receptacle as its FEED 120 power.
4. The box on the bottom of your power center is the Magnetek Power Converter itself.
5. The ONLY stranded wires will be the 3 120 wires FROM the 30 amp Power cord in the pic where you are holding the soldered wire. The other stranded wires will be that black soldered wire you are holding and the WHITE Neutral wire that runs from the CONVERTER along with the Black soldered wire that connects to the 30 amp breaker
6. Remember, EXCEPT for item 5 above. any other stranded wires will be 12 volt DC wires. The Romex 120 wiring leaving the Breaker panel going to 120 receptacles and 120 appliances will be solid core copper.
7. Here is where it gets tricky. From your last 2 pics, it appears the 12 volt DC wires were 2 stranded Black and white together. USUALLY, the WHITE is the Ground/Negative. The BLACK will be 12 volt positive. This is standard RV wire color. Don't use Automobile color standards.
I state this because you stated the WHITE wires were all together on an outside the power center wire BUSS. They use a common Ground. The Black wires will be connected to the 12 volt fuse panel. Doug
