07-01-2009, 08:12 AM
Had something similar happen once. I had built a power supply for turnout control. I was using twin solenoid (NJ International) machines for the turnouts in the throat of hidden staging yards. I was also using a diode matrix to throw routes, so needed enough power to throw 5 machines at once. My knowledge of electronics is small, and when the first transformer I used did not have the oomph required I bought one of a higher voltage. Still no good, I found it was the amperage that was too low, so had to buy a fairly pricey xformer, but back to 12 volt. Seems the lower rated units had their voltage drop to 1 volt or so when the load of the machines was put on them. Well, the new and satisfactory unit was in operation for a short while when I had friends over to run. I use a probe and stud system to avoid having push switches weld themselves together, which was the case as I tried them. At one point, I smelled burning. Tracing the smell took a minute or so. I yelled out to kill the power to the turnout power supply, as I was 20' away. Turned off immediately by a friend nearby, we then found the problem was that the wire used as a probe had attached itself to the bolthead stud! Whoever had thrown the turnout hadn't noticed! The metal plate on the switch machine had gotten so hot it was burning the 1x4 it was mounted to! I did already have fire extinguishers at both ends of the layout, thankfully they weren't needed. However, I did immediately find out the values required to fuse both the primary and secondary sides of the xformer, and installed them!