During Tuesday night’s operating session it was brought to my attention that locomotives were stopping when they entered the turnout at Ballardvale Junction. I took a look and what I saw was as soon as the locomotive’s wheels touched the frog it would stop and the lights would go out.
The immediate conclusion I came to was that there was a short. This conclusion was further supported by the fact that this was a fast tracks turnout built by soldering the rails to copper ties. The ties need to have the copper on the surface interrupted at key locations or it creates a dead short. The rails on both sides of the frog are cut to electrically isolate the frog since the polarity needs to change depending on the switch orientation. The copper ties soldered to the frog are all cut to isolate the frog as well. Since the frog is electrically isolated via the rails being cut, it all made sense to me that if one of the ties wasn’t completely cut through as soon as the wheels touched the frog a short would occur.
I thought this would be a simple fix. I grabbed my triangular shaped file and hit all of the copper ties soldered to the frog. Sometimes the tiniest remnant of copper will be enough to short. I had Ace run the locomotive through the turnout but nothing changed, still stopped as soon as the wheels touched the frog.
The next possible cause was a little more difficult to resolve. I have had previous fast tracks turnouts create a short if the feeder wire wasn’t soldered properly. I attach feeder wires to the bottom of the track prior to installation on the layout. If the feeder wire happens to inadvertently solder to an adjacent copper tie on the bottom side of the tie instead of just the intended bottom of the rail, then you know what happens, a short. I now was convinced that this was more than a quick repair and would need follow up after the ops session was over.
So last night I continued with the process to resolve this short. I started with my ohm meter expecting to confirm that the frog was not isolated from one of the stock rails. Once I determined which side, I would cut all the way through the copper rail adjacent to the feeder wire to break through the bottom side copper. To my surprise the frog was isolated from both stock rails. Know I’m really scratching my head. I ran a locomotive through the turnout and once again as soon as the wheels touched the frog it came to a complete stop and the lights went out.
Know I’m grasping for straws. I checked all the feeder wires to this turnout and adjacent track to make sure the black and white feeders were connected to the black and white bus lines, even though I knew if they weren’t there would have been a short all of the time. Everything was wired properly.
Not sure where to go from here I grabbed my volt meter and started measuring track voltage. I was completely “shocked” to discover there wasn’t any voltage in the turnout. This turnout is at one end of a detection block that spans from Lowell Junction to Ballardvale Junction. For this reason the rails just beyond the turnout are cut to isolate this block from the next one. I then noticed that the rail within the block entering the turnout did not have a rail joiner on one side.
Further observation showed that by pure coincidence, the length from the first locomotive wheels to the last exactly matched the distance from the block isolation cut to the frog. How could Murphy be so cruel?
My focus was now on the feeder wire from the bus to the turnout on the side without a rail joiner. Everything visually looked fine. I proceeded to open the suitcase connector at the bus. My plan was to remove the metal blade, trim the end of the feeder wire, and reattach the feeder to the bus. No matter how hard I tried I couldn’t pry the blade out of the connector away from the wire. Eventually I was able to remove the connector from the bus wire.
A little explanation about how the suitcase connectors work. In this case I’m using one that is designed to connect different gage wires. (In my case #18 feeder to #12 bus.) The metal blade has slits in it that are just the right width to cut through the insulation completely and tightly slide over the wire. So in this case a wider slit to fit the #12 and a narrower slit to fit the #18.
It is not unusual for this metal blade to fall out of the plastic housing when in the box. Several times I have simply picked up the metal blade and reinserted it into the plastic housing. But in this one case, I reversed the blade so the narrow slit was aligned for the bus and the wider slit was aligned for the feeder. When I engaged the blade, the narrow slit wouldn’t fit around the large bus wire. One side slid against the copper and the other side folded over, thus causing the difficulty I had trying to remove it.
And as far as the wider slit fitting over smaller feeder wire? I learned the hard way that the width of the slit was wider than the feeder copper and even though it partially cut through the insulation it never made contact with the copper.
Mystery solved. Locomotives run perfectly through the turnout.
Model Railroading is FUN.
