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The Randall Museum in San Francisco hosts a large HO-scale model model railroad. Created by the Golden Gate Model Railroad Club starting in 1961, the layout was donated to the Museum in 2015. Since then I have started automatizing trains running on the layout. I am also the model railroad maintainer. This blog describes various updates on the Randall project and I maintain a separate blog for all my electronics not directly related to Randall.

2019-07-28 - Elusive electrical issues with block B350

Category Randall

Lately the automation has been partially stopped due to this:

The automated UP passenger train stops in the middle of the grade going up to Summit. No electrical power.

My first reaction was of course to open the block panel, toggle the block a few times and it started working again. Yeah, fixed, right? Probably a bad contact in that 50-year old contact switch.

And a couple days later it happens. Same, as soon as I touch the toggle for block power, it starts working again. OK so now I just bypass the toggle and I connect the lead for block 350 directly to block 340. It starts working again and a few days later… it stops working again. Yet as soon as push the train back into block 340, it gets power again.

So my suspicion now is a bad solder somewhere between the block panel and the track feeders. Now I have to go crawl under the layout and look a bundles of 20+ similar red wires to see if I can identify which one to follow.

Looking back at my notes from 2017, I noted that B350 was odd. I have a track block detector before on B340 and one after on B360, but none on B350. My notes indicates when I tried, a train in B350 was poorly detected and actually registered sometimes at B340. So I one wild totally unfunded theory is that maybe the track feeders for B350 are not properly powered and someone did a quick fix by bridging the gap between 340 and 350. I have actually seen exactly that kind of work on another part of the layout. That’s the joy of working on a 50-year old layout that has been modified by different people with different standards and different aptitudes levels over decades with no accurate work documentation.

In between I modified the automation to have the UP passenger train stop and reverse at block B330, just on the canyon bridge. People loved it when I tried that, as that location is right in front of them. And kids being kids, they don’t care as long as it moves… That way I can take more time to concentrate on finding the real cause.

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