I have been reading about 21 pin decoders and adapters that allow you to connect a 21 pin decoder to a 9 pin plug. What's the advantage of the 21 pin decoders. Do I have to swap all of my 9 pin decoders for 21 pin decoders? And if ultimately the connection to the engine is through the 9 pin harness, what's the reason forusing a 21 pin decoder?
Lefty
The reason for so many pins is the number of functions. Forward light, rearward light, four ditch lights, cab interior lights and so on. If you don't need all those functions and you already have a nine pin decoder, than your all set.
Pete.
As mentioned, the 21 pin (21MTC) decoders support a lot more functions. Some function outputs can be logic level, allowing additional function connections via logic circuits on the daughterboard. For a manufacturer, using a daugherboard and soldering all those wires to it is much easier. Then install an appropriately programmed decoder onto the daughterboard. Or the customer can install one later.
The adapter boards give you access to those additional functions as well. In addition to eliminating the need to solder a lot of wires onto a small PCB.
If you are not interested in all those additional features a 21MTC type decoder supports, there is no need to change your existing decoders.
abbieleibowitz I have been reading about 21 pin decoders and adapters that allow you to connect a 21 pin decoder to a 9 pin plug. What's the advantage of the 21 pin decoders. Do I have to swap all of my 9 pin decoders for 21 pin decoders? And if ultimately the connection to the engine is through the 9 pin harness, what's the reason forusing a 21 pin decoder?
What is the socket arrangment on the motherboards of your various locomotives?
Are they all 8-pin configurations?
Rich
Alton Junction
Changing from 9 pin to 21 pin decoders is something I have been considering. My 9 pins are older Digitrax and quite frankly, are a pain to consist with non Digitrax decoders. I have switched to ESU for my 21 pin decoders and find them much easier to consist and program. I would gladly like an adapter to go from 9 to 21 pin and would begin that transformation. That's why I would switch.
Steve
Hi Steve.
Are you wanting sound decoders or just motor and lights? Are there 9 pin plugs already in the locomotives? Have you considered other brands of decoders? How much room is there for a decoder?
I haven't seen any harness or direct plug from 21 to 9 pin interface. You may have to buy 21 pin motherboard such as Nix trains decoder buddy. Soundtraxx also makes buddy boards. I haven't used them. The Nix trains boards have resistors already installed on the board for LEDs and a little bit larger solder pads for us old blind guys.
Have you tried something like a TCS T1 decoder? Small size direct plug 9 pin JST. They have really good motor control and decent lighting outputs.
I don't think there's much reason to replace an existing 9-pin decoder for a 21-pin unless the new 21-pin has features you want and the 9-pin doesn't have.
However, if (like me) you have some older engines with a lightboard with an 8-pin receptacle that you want to upgrade to sound, it looks like if you shop around you can get a good 21-pin sound decoder cheaper than a 9-pin one - even including the cost of the 9-to-21 pin conversion gizmo (or replacing the lightboard with a 21-pin "Decoder Buddy").
The one benefit without sound, is the decoder board from Soundtraxx to replace the motherboard to allow a 21 pin, is most of theirs have built in capacitors for keep alive.
Now, finding the time to do said replacements I can't help with........
Ricky W.
HO scale Proto-freelancer.
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wrench567I haven't seen any harness or direct plug from 21 to 9 pin interface.
Soundtraxx makes one. You plug the 9-pin in one one side, and plug the 21-pin on top. It also has solder points for FX connections (like extra lights) and for their "Current Keeper".
https://www.trainworld.com/soundtraxx-810159-jst-21pnem-adapter-soundtraxx-810159.html?qty=1
I recently bought one, but haven't tried it out yet so can't comment on how well it works. Hope to use it shortly though.
Be careful with adaptors for 21 pin decoders, as there were two different implementations until the NMRA re-aligned their pin assignements to match the NEM standard. US brands manufactured before 2021 may have differences in pin assignments compared to the European brands.
Thanks, I wasn't aware of that. In this case, I plan on using the Soundtraxx adapter with a Soundtraxx decoder, so I assume it will be OK.
wjstix Thanks, I wasn't aware of that. In this case, I plan on using the Soundtraxx adapter with a Soundtraxx decoder, so I assume it will be OK.
You should be ok with any brand of 21 pin decoder. Decoders made for Marklin and other European models will state that in the description. They are usually a special order item in the US and Canada.
I just wish more companies would adopt the next 18 interface. An email I sent to Nics trains the maker of the Decoder Buddy boards asking about that. The reply was that it was in the works. I had already used the Nano Loksound 5 decoders in a pair of Bowser Baldwin switchers using the N scale WFD boards that worked out nicely. Really small and compact. The N scale guys should be asking for more of these types of interface.
PluX vs. 21MTC...
The NMRA defines the PluX interface, ESU designs the 21 pin Marklin/Trix Connector.
The 21MTC interface becomes a de facto standard because ESU is a popular OEM with the manufacturers. Even Bachmann gets on board. So the market is full of locomotives with 21 pin decoder interfaces...
betamax The 21MTC interface becomes a de facto standard because ESU is a popular OEM with the manufacturers. Even Bachmann gets on board. So the market is full of locomotives with 21 pin decoder interfaces...
richhotrain betamax The 21MTC interface becomes a de facto standard because ESU is a popular OEM with the manufacturers. Even Bachmann gets on board. So the market is full of locomotives with 21 pin decoder interfaces... On my most recent locomotive purchase, I bought a pair of Athearn Genesis F3AB locomotives that came factory equipped with a 21-pin circuit board. I simply added a drop-in Soundtraxx MC1H104P21 to each locomotive. Rich
On my most recent locomotive purchase, I bought a pair of Athearn Genesis F3AB locomotives that came factory equipped with a 21-pin circuit board. I simply added a drop-in Soundtraxx MC1H104P21 to each locomotive.
That was what ESU was going for: Easy to install with a defined form factor for the decoder. During assembly they can install a decoder quickly, and if it is defective it won't take long to remove and replace it. The designers don't have to go out of their way to accomodate a specific decoder's dimensions, as all 21MTC decoders are the same size.
Also makes it quite easy for the enduser to upgrade decoders or install one in a "dcc ready" locomotive.
What's not to like?
betamax richhotrain betamax The 21MTC interface becomes a de facto standard because ESU is a popular OEM with the manufacturers. Even Bachmann gets on board. So the market is full of locomotives with 21 pin decoder interfaces... On my most recent locomotive purchase, I bought a pair of Athearn Genesis F3AB locomotives that came factory equipped with a 21-pin circuit board. I simply added a drop-in Soundtraxx MC1H104P21 to each locomotive. Rich That was what ESU was going for: Easy to install with a defined form factor for the decoder. During assembly they can install a decoder quickly, and if it is defective it won't take long to remove and replace it. The designers don't have to go out of their way to accomodate a specific decoder's dimensions, as all 21MTC decoders are the same size. Also makes it quite easy for the enduser to upgrade decoders or install one in a "dcc ready" locomotive. What's not to like?
I have a variety of loco's older and newer, such as yellow box Genesis and newer Blue box Genesis. I'm guessing the older ones had the 8 or 9 pin socket and the newer ones 21 pins. I assume if I need to install newer 21 pin decoders in the older engines, I can buy some decoder buddies from Nick.
Rio Grande. The Action Road - Focus 1977-1983