Author Topic: RailPro and Decoder Buddy  (Read 1426 times)

Jeff1022

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RailPro and Decoder Buddy
« on: August 01, 2026, 06:27:38 PM »
I was talking with Nick of Nix Trainz at the recent St. Louis RPM meet and he told me that his "Decoder Buddy" board would work with a RailPro module.  I'm just getting my feet wet with RP, but his boards have a 21 pin receptacle and I believe the modules are a 9 pin.  So, how can this be true per him?  Has anyone been able to make these work together in some manner?  I also inquired about his "Stay Alive" capacitors and he said he had never tried it, but he did use another brand stay alive with a RailPro module once and it worked.  So, give it a try and see is all he had on that. 

Any thoughts from the group will be greatly appreciated.  Thanks. Jeff Youst

G8B4Life

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Re: RailPro and Decoder Buddy
« Reply #1 on: August 01, 2026, 08:16:01 PM »
Ring has both 21 pin and 9 pin LM's  available. The 9 pin LM would require an adapter harness to use the Decoder Buddy board, the 21 pin LM would fit directly.

As for "Stay Alive" devices, never used any so I can't answer that but in theory any Stay Alive should work however some that are built into factory motherboards in models do not work properly without the specific DCC decoder they were designed for seemingly due to a mismatch in control voltage levels. Ring has their own Stay Alive, the PBM which they try to spruik as the only safe Stay Alive for RailPro.

- Tim

sieggs1

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Re: RailPro and Decoder Buddy
« Reply #2 on: August 04, 2026, 10:33:57 AM »
Hey all,

I use the Decoder Buddy with RailPro LM-3S-21. Yes, you can use a Keep-Alive with the pins on the Decoder Buddy. RailPro's own works but I have also been making my own keep-alives for much cheaper and they last longer.

Rob S.

Tom

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Re: RailPro and Decoder Buddy
« Reply #3 on: Today at 08:42:16 AM »
I recently bought a DCC ready loco with a 21-pin plug but want to use an LM-3S module.  Is there such a thing as a 21-pin to 9-pin adapter?

LVRR1856

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Re: RailPro and Decoder Buddy
« Reply #4 on: Today at 02:17:16 PM »
Here is a 9 to 21 adapter, not sure why it's called "European", for $12 .... maybe worth a shot ?

Just google 9 pin to 21 pin dcc adapter ....

Screenshot 2026-08-07 151413.png

gregeusa

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Re: RailPro and Decoder Buddy
« Reply #5 on: Today at 05:32:05 PM »
21 pin standard started in Europe I believe
Lots of tips and techniques on my site: www.elmassian.com contact me greg@elmassian.com