LM-2S install on Bachmann J 4-8-4

[Ten42]

Hello everyone,

Railpro user for a few months now as well as being new to the hobby. My first railpro install was pretty easy as it was plug and play basically. The only thing I had to do was solder a speaker wire. I just received my Bachmann J 4-8-4 #611 and when I took it apart to see what I needed for the install, I felt overwhelmed. It has a soundtraxx board in the tender and no plug/pin. Would it be best to solder a 9 pin to the soundtraxx board to plug into the LM-2S or should I do something different? I have searched the forum along with other sites looking for direction but haven’t found any, so any advice would be greatly appreciated!

[Alan]

According to Bachmann's site the loco comes with a dual-mode DCC module as well as Soundtraxx. That tends to make me think complete electronics removal and hard wire of LM is in order.

[G8B4Life]

If it looks like this


Image credit: Model Railroader

Then yes you'll have to remove the existing decoder and hardwire the LM in. To hardwire it in my suggestion would be to cut a piece of PCB vero board to the same size as the existing decoder and hardwire everything to that (essentially making your own motherboard) rather than trying to solder wires together. I think I remember there being pics of someone having done that somewhere here on the forum.

- Tim

[Alan]

To hardwire it in my suggestion would be to cut a piece of PCB vero board to the same size as the existing decoder and hardwire everything to that (essentially making your own motherboard) rather than trying to solder wires together.
- Tim

Agreed.

Another option for DIY motherboard is IC prototype boards. While designed for building test IC circuits, they can also be used as soldering points. Readily available and very inexpensive, they are ideal for a situation like this. A single board gives you 20 circuits with 6-7 connection points per circuit, more than ample for any LM install. Or slice in half and trim the edges to get two very small 10 circuit solder points. A 15 watt iron works well.

[Ten42]

Thanks gents! I’m currently working on my first hardwire so fingers crossed it will work after I’m done, haha. I must admit though, DCC decoders kept me out of the hobby until I found railpro. Everything seemed that it was a bit complicated until I found this forum and read everyone’s comments about the railpro stuff.

[Ten42]

Well I’m getting a fault on one of my outputs and the LM-2s feels hot... it smells cooked...

[Alan]

If it is getting hot yet still working then you don't have a direct short as that would cause the LM to immediately shut down. It sounds like you have a low resistance path somewhere in the output wiring causing the LM to work at its upper limits of current supply. While an LM has built in over-temperature and over-current protection that should kick in, it is an electronic device so it is still possible to release factory sealed smoke. Don't operate the LM again until you find and fix the issue.

An LM lighting output max is 1A. At 14.8V that equals 14.8 ohms. Place a multimeter across your wiring (disconnected from LM output). The resistance measured should be well above 14.8 ohms.