I have three new Legacy steam locomotives, and all of had a common issue. Crossing certain switches cause the sound to drop out. No problem I thought, I actually designed a product to take care of this specific issue with Legacy steam locomotives, the YLB - RailSounds Battery Replacement (RS-Lite). So, I popped open the tender and with my YLB in hand, I prepared to fix this annoying issue.
SAY WHAT??? There is no battery connection for the new boards!
After a little detective work, I found an interesting configuration for the filter caps on the board. First off, they had thru-hole caps on a mostly surface mount board. I suspect that component shortages may have dictated the change, I know I can't buy a 220uf 35V SMT cap to save my soul! There are two caps on the board, the negative terminals are common, but the positive terminals are separated by a diode. Now, that's a somewhat curious configuration that I haven't seen before, but I'm guessing it was to prevent the second cap from being discharged back through the track connection, it would be interesting to see the whole circuit drawn out. Not sure exactly what was intended, but I decided that was a good place to tap into the raw power.
By adding a 2200uf 35V cap, I was able to increase the sound hold-up time to several seconds, more than enough to transition the brief track power interruptions of slow running over a switch.
I used a small piece of double-sided foam tape to secure the capacitor inside the tender, job done. At about ten minutes for each of my three new Legacy engines, I had this project all wrapped up in half an hour!
The after effect of adding the fix, before the fix the sound would drop out at slow speeds over either of the double slip switches or the curved switches on the layout. Now I can go around as slow as possible and no sound dropouts.