The Randall Museum in San Francisco hosts a large HO-scale 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 Museum Model Railroad and I maintain a separate tech blog for all my electronics & software not directly related to Randall.
2026-01-03 - Randall Repairs: Block B350
Category RandallAffected |
Block B340/B350 up the mountain. |
Description |
Joiner solder gone bad again. |
Summary Fix |
Resolder the joiner. |
Description of Issue
We’ve had the UP Passenger train go dead going up the mountain yesterday at the junction between blocks B340 and B350. It did work twice in the morning before it totally lost power. Then this morning it was powered fine, and later the Saturday Operators folks reported a loss of power on that same block.
Orion was there and examined this more closely:
That seems very familiar because I’ve seen that happen already back in 2019 at the exact same spot. You can read that report to get the details. The bottom line is that the joint between these two rails failed again.
Description of Fix
The immediate fix done by Orion was to reflow these track joints:
However this is clearly a temporary fix. That means in any number of years, we’ll get the exact same issue at this spot again. My opinion is that we’re seeing the result of track expansion or contraction due to weather, and a hard joint will inevitably fail sometimes later. The real solution is a bit more involved and involves using “bond wires”: That means removing the solder between the two rails to leave an expansion gap, and then soldering a piece of wire on both sides yet free to flex in the middle.
Fix time: < 1 hour.