Saturday, January 14, 2017

Setting Up the DCC System Part 4: Program Track

Actually wiring the program track has taken quite awhile! A post from last summer shows the program track switch soldered up but not yet installed.
Soldering feeders to the underside of the interchange track,
which will also serve as the dead zone and program track.
Part of the reason for my delay (read that as procrastination) is that I want to improve my scenery technique by soldering the feeder wires to the underside of the track rather than adding the feeders after the track is laid. While unsightly solder blobs and visible wires will be avoided, two clearly delineated steps with their own sequence of installation are now intertwined into one. Apparently it has been easier to motivate myself to tackle other projects such as researching operations, prepping rolling stock, preparing a clinic, or starting buildings rather than wiring and laying track with this "improved" system.

In researching the wiring for DCC I found that some consider using a DPDT switch to alternate an isolated section of track between track power and programming to be potentially dangerous. If a locomotive accidentally bridges the two while in programming mode, it can damage the programming circuitry of the DCC system. Including an isolation or "dead zone" section between the programming track and the rest of the layout is the recommended solution. The schematic to wire this up using a mouser.com 4PDT ON-OFF-ON is shown below.

Program and isolation track schematic
Right before the holidays I screwed the panel mounted switch to the opening in the fascia, soldered the feeders to the underside of the track, connected to the program output on the command station, and "suitcased" to the DCC bus. It DIDN'T work! After troubleshooting, cutting wires, and grumbling, I deduced that the suitcase connection was faulty. After re-soldering feeders to two of the connections on the switch and reattaching them to the DCC bus, I had success. I had originally bought in to the infallible nature of suitcase connectors; while still using them, I am not as trusting. One issue is that the red suitcase connectors from MicroMark do not have double blades, nor do they have the opening to view the second wire. I suspect that using slip joint pliers at an angle from under the layout may have had a part in the initial faulty connection. This kerfuffle has not added to my enthusiasm for wiring, but I am now able to program or use the track as an interchange without fear of damaging circuitry.

Interchange track successfully wired as programming track
with toggle switch and indicator light in fascia