Installing a “Keep Alive” or similar circuit

[Lackawanna810]

Can anyone tell me which “Keep Alive” or similar circuit can be installed with the LM-3?

Thanks in advance for the due diligence.

[nodcc4me]

The RailPro PBM2 was designed for keep-alive purposes.


https://www.ringengineering.com/PBM.htm

[CPRail]

Alternatively, you can connect any of the TCS Keep-Alive units to the blue wire on the 9 pin side (blue wire on KA), and the yellow wire on the 6 pin side (black-white wire on the KA). Bill did up a nice diagram on this and you can find it here:
https://www.pdc.ca/ShopSuey/app/vendor/jQuery-File-Upload/server/php/uploads/Wiring%20Diagram%20for%20LM-3%20to%20TCS%20Keep-Alive.pdf

I don't believe this is "officially" sanctioned by Ring, but it works. I know there have been past discussion on how the PBM-2 is better, but when space is tight, you can still connect a TCS KA.

[ON28]

Until I switched to PBMs I used the TCS keepalives and I agree with RailPro godfather, Lee Nicholas, who told me, "They don't really work."

[Lackawanna810]

In reading the PBM manual, it says that it can only be used with HO scale locomotives. I model in S scale. I guess this means the PBM is out.

[G8B4Life]

The manual says should not, not must not. My guess is that's to prevent the PBM from being damaged by using it in a scale that would typically have higher power requirements, like 0 scale and larger. I don't know what the typical power requirements are for S scale but if your using the standard size LM's and not the G size then I can't see what the issue would be with using them. Logic dictates that if your using the designed-for-H0 LM's then you should be able to use the designed-for-H0 PBM's with them.

Obligatory however though, I'm not the manufacturer so what I've said is to be taken with careful consideration.


- Tim

[Lackawanna810]

That makes sense. I’ll try the RPM in my engines.
Do I need to splice into decoder loom wires to connect the RPM?

[G8B4Life]

...Do I need to splice into decoder loom wires to connect the RPM?

No, depending. The LM-3 and LM-3S you just connect the PBM to the relevant wires on the 6 pin harness (solder wires together) . The LM-3S-21 the PBM will connect to the relevant traces on the mother board in the locomotive (solder wires to motherboard). The old LM-2 and LM -1 series are not designed for the PBM. Ring made a mention about a board to allow use with the LM-2 back when the PBM was released but nothing yet.

The LM and PBM manuals will cover all that you need to know.

- Tim
 

[Lackawanna810]

Thank you Tim. I was wondering about the mentioned board for use with the LM-2.

You've cleared up a lot for me here, and I am grateful to you. Thanks so much.