Has your BLI loco lost its chuff?
At a recent operating session a friend asked me if I knew why his BLI Mikado had lost its chuff. All the other sounds were still there, just no chuff. After a little research on the internet I discovered that this is a fairly common problem with BLI steam locomotives. Instead of depending on the type of automatic synchronization schemes used in most other decoders, the BLI steamers use a magnet and reed switch detector method. A magnet is attached to the main driver and a reed switch installed on a circuit board directly above the magnet detects every time the driver makes a revolution. Inside the reed switch two metal electrodes close each time the magnet passes, and then they open again. The intermittent electrical contact they make is transmitted to the decoder which then uses that signal to synchronize the chuffs with the drivers’ rotation.
So what goes wrong and how do you fix it? Well, those little electrodes end up making a lot of movements and eventually they can stick together or even fail. When that happens the chuffs stop. Some folks say they have had success tapping the reed switch, but that usually only lasts a little while. Eventually you either have to send the locomotive back to BLI for replacement or order one from them and do it yourself. Although I have several BLI steamers I haven’t operated them long enough for this problem to arise but I do plan to order a couple reed switches from BLI for the day when the chuffs stop.
Replacing the reed switch involves removing the boiler upper half so you can get to the reed switch circuit board located over the drivers–here’s where that exploded diagram will come in handy. Then you have to unsolder the reed switch and install the new one in its place. This sounds like a simple enough procedure, once you get the boiler apart, and there are several posts on the MR website forum from folks who say it was fairly easy. The included photo shows the reed switch in a N&W steamer, it looks like a resistor in the center of the board. Good luck with it.