The Rewiring Never Stops!

I posted in April about having to troubleshoot a current drain in an older part of my layout. I thought I was done, but not much later, a week or so after I had all the trackage back to 14.2 volts DCC, I got another current drain out of the blue, this one not so bad, but it really hurt operation.

I did some searching on the web for advice on DCC troubleshooting, but the consensus seems to be that no two layouts are alike, so there are few good general guidelines. In addition, I recognize yet again that the oldest parts of this layout are 30 years old, pre-DCC, wired for DC dual cab operation with 22 gauge wire and DPDT toggle block control. There was a time a couple months ago when I seriously thought about scrapping everything, although I'm probably too old to start over, realistically speaking.

When I shifted to DCC in 2012, I simply disconnected both the DC walk-around throttles and connected an NCE PowerCab to one of the 22 gauge block buses. This worked until early this year, when the combination of sound decoders, the resistance from 22 gauge wire, power extender capacitors in locos, and stationary decoders for switches and lighting overloaded the PowerCab, and I moved to an NCE SB5. At the same time, I left the 22 gauge block wiring in place, but I bypassed it with a new 14 gauge DCC bus. But I didn't disconnect the 22 gauge block wiring. I thought that theoretically, this wouldn't be a problem.

Clearly there were gotchas. One was that the 22 gauge wiring was up to 30 years old, and insulation wore off, and solder joints came undone. I began to realize that I was going to have to bite the bullet and remove all the 22 gauge wiring with all the block toggles, running new drops off the track to new terminal strips connected to the 14 gauge DCC bus.

Somewhat daunted, I took a couple months off and worked on my T-TRAK modules until my interest in the HO layout renewed enough to tackle the rewiring. That took place over the past few weeks, and I've made a lot of progress.

The big problem I discovered that caused the latest current drain was something called an X-section. This was an innovation invented by Linn Westcott for DC block control that basically eliminated the need for an extra DPDT toggle where a CTC type siding blends into a single track main. You used the relay contacts on the (AARRRGHH!) twin coil switch machine to route the block current from either the main or the siding at the control point onto the single track part of the main, so the block control automatically routes to the single track main from either the main or the siding.

Somehow I'd managed to replace the twin coil switch machine that controlled the X-section with a Tortoise, but I didn't update the X-section wiring. In fact, when I installed the Tortoise, I'd completely forgotten about the X-section. Somehow this continued to work, until I replaced the PowerCab with an SB5. Once I revisited this part of the layout and completely removed the 22 gauge block wiring in the area, it solved the problem. But as they say with DCC advice, no two layouts are alike. I doubt if anyone could have identified the problem for me.

Here are some photos of this monster project in progress. Fascia has been removed in several photos, but I've never been able to wire neatly.

Above, you can see a block panel pulled out, with 22 gauge block wiring in the process of being removed. Luckily, I can recycle many of the DPDT toggles for other projects. You can also see the now-unused phone jacks for the former DC walkaround throttles. Just to avoid confusion, I will need to get around to removing these.