Wednesday, June 24, 2020

Electrical wars, Part 17: staging

I have written a number of posts on the topic of finding and fixing electrical problems on my layout, as you can perceive from the series number of the title. (To readily find any of the previous posts in the series, use “electrical wars” as the search term in the search box at right. ) These posts do not represent any particular sequence or linked events, but describe separate electrical challenges I have dealt with.
     (I guess this series of posts is about “wars” because electrical problems make me feel like I am about to confront a challenging task. Luckily it’s not always that bad in the event.)
     This latest challenge arose in my layout staging, which is a 12-track transfer table. It has generally been pretty dependable since I built it, about ten years ago, based on a design by John R. Signor  (though some of the trackwork needed revision after some time operating with this staging, as I showed: ). Here is an overall view of the table, located beneath the town of Ballard on my layout.

This view shows the staging largely filled with freight cars, mostly consists of through trains, with only a few of them having locomotives. Since the photo was taken, this has evolved to where the majority of tracks contain complete, powered trains.
     When my staging tracks suddenly went dead recently, I started investigating what could be wrong. One problem I quickly discovered was that one of the staging tracks no longer had power at one end. Putting my trusty meter to work, I soon found the reason: a somewhat wide rail joint (foreground) had a broken solder connection, making it connect only intermittently. (That’s half an Atlas re-railer at left.)

This was quickly re-soldered and the track then functioned as it should. 
     But the larger problem recurred, essentially all tracks in the staging table going dead. It happened once, corrected itself, and then went very reproducibly dead. I then had to trace the path of power into the table and its distribution to the 12 tracks.
     Electrically, my control of the staging relies on a pair of 6-position rotary switches so that I can select any of the 12 tracks, with a switch between them to select which rotary is live. These controls were set up on a pretty simple panel (photo in this post: ). Shown below is the back of this panel, shown not because it is any kind of electrical marvel nor because of its incredibly neat workmanship, but only to illustrate the area in which I had to trace continuity,

The two rotary switches, at top, and the selector switch between them, are all evident. Below them is a pair of “on-off” switches, so that even when a track has been selected, it is not automatically powered unless I operate that switch.
     Power comes to this panel at the selector switch, then to the two “on-off” switches below, then to the rotaries. From the rotaries, the wires carrying power to each individual track head off to an array of terminal strips, as you see below, and thence to the tracks themselves, as are visible across the bottom of this photo. The view is looking up at the underside of the staging table.

The track numbers 1-12 are identified next to their part of the terminal strip and also by the feeders below them, through the plywood. The two multi-pin connectors visible (one of them end-on), bringing track power from the rotary switches, are so that the panel can be removed from the layout for work, without un-soldering or unscrewing anything.
     All this is documented in my “Layout Notebook” which contains many sketches of benchwork construction and of electrical arrangements, including identifying every wire by color and by its purpose in a particular area (I showed a page from this Notebook in an earlier post, which is at this link: ).
     With this information in hand, I could start tracing the path of track power through all the complications shown above. I soon found a broken wire at one of the panel switches — how it was broken I don’t know — but readily re-soldered. Sure enough, the staging table then functioned perfectly.
     I tell this tale only to illustrate how one can trouble-shoot even complex wiring arrangements: if there is good access to that wiring, and if it is all documented so that you know what you are looking at, even ten years after you assembled all of it. That was this case for this problem.
Tony Thompson

No comments:

Post a Comment