Lionel Semaphore

You have described MPC 2151 normal behavior. The solenoid coil in the base is not energized when showing the default "red" position and is energized (pulling on the arm) in the green position. Note that the postwar 151 displays the opposite indications but works identically.

When using a traditional contactor, the weight of the train passing completes the circuit, when the train weight is not there, the circuit is broken. Essentially, you use the contactor as a switch of the wire going to the coil. You may need to adjust the contactor so that the activation "weight" is correct. Note that a 153IR or traditional insulated rail section is much less finicky than the weight-style contactors.

Wiring methodology:
1. The middle binding post is common. One wire should go to the middle binding post and to U/black/common on your transformer or the outside rail.
2. A second wire from ABCD/red/hot on transformer or the center rail to the lamp binding post and a similar wire to the contactor clip 3.
3. Another wire from contactor clip 2 to the coil binding post.
You want the contactor to be normally open (off unless activated) to prevent coil burn-out.

Note that clip 1 is normally closed (on unless activated).

EDIT: consolidated for brevity.

Thanks. What is supposed to trigger the thing to move? I can only get it to move by applying power directly. How is the 153C supposed to work?

Is there any electrical connection between the track and the 153C?

Hey I fixed it! I had the wire on post 1 instead of 2. Thanks!!!

My four year old is going to lose his mind tomorrow when he sees this thing finally working!

Here's a helpful video:

Jon

Thanks for the video. Interesting explanation about real-life operation. I think that guy’s track must have been salvaged from the bottom of the ocean!