Second build seems to be functioning properly. 
bmoran4 posted:A few relevant notes that explain your observations:
- Most single train transformers swap the common terminal and variable terminals from the multi-train transformers. The postwar multi train transformers traditionally have U as common, whereas the single train utilize U as the variable voltage. I'm not sure what traditions the CW and 4090 follow. Regardless of transformer, this is remedied by ensuring the common (regardless of lettering convention) is wired to the outside rail, and the variable voltage to the center rail.
- The Whistle and Bell work off of a DC offset layered on the AC current. The polarity of this offset determines articulation of the Bell or Whistle. Swapping the terminals swaps the polarity. Note that the postwar whistle/horn relays work regardless of the polarity.
So what you're saying is that I'm doing it right; It's the transformer to blame.
The 4090 has four posts. U-A-B-C. It has two handles. One is Direction/Whistle, the other is Power
- A-U = 5-14v
- B-U = 0-11v (This pair is great for Marx stuff as they need next to no voltage to fly off the track
) - A-B = 5v
- B-C = 11v
- A-C = 16v
The logic you've specified seems to make sense as the U post is the only true variable output.
