KB349: Decoder Ready Locomotives?

This article was last updated on Oct. 17, 2010, 1:01 p.m. | Print Article | Leave Feedback

When purchasing a loco that says its decoder ready, exactly what is implied? Does this mean wires can be wired into the numbered locations and nothing else is needed except to remove jumpers?

As with any technology, it takes time for standardized terminology to become established.  Although DCC is almost twenty years old, there are still some gray areas with descriptions.  It really depends upon the individual manufacturer, and within one manufacturer's product line there can be variances also.  There are several types of locomotive decoder installations and you may find that these terms are not applied by all manufacturers in the same way:

  • Factory Installed Decoders - Basically, a locomotive with a factory installed decoder is ready to operate right out of the box.  It is not unusual for abmodeler to remove the factory installed decoder and replace it with another brand, usually to gain additional features offered by more advanced decoders or to avoid known issues with the factory installed decoder. 
  • Plug N' Play Decoders - A locomotive may be equipped with one of the many different standardized sockets.  The locomotive comes out of the box with a jumper plug installed in this socket, allowing the modeler to operate the locomotive in a DC environment.  DCC conversion is accomplished by removing the jumper and plugging in a decoder which is equipped with the same type of plug.  In many cases, there are several Plug N' Play decoders to choose from; there are decoders with just headlight function and other decoders that have additional functions up to and including sound.  Sometimes, there is a specific Plug n Play decoder for a specific manufacturer's locomotives. 
  • Drop In or Board Replacement Decoders - A locomotive may be equipped with a circuit board that can be removed and replaced with a drop in decoder made specifically for that locomotive.  Occasionally, minor modifications are needed for drop in installations.  For some N Scale Drop In installations, a frame modification is needed to allow the decoder to fit the locomtoive, especially in sound installations.
  • Hard Wired-Custom Installed Decoders - In this case, the decoder wires are soldered by the installer to the motor, track, function and sound contacts inside the locomotive.  In addition frame modifications may be needed for this type of install.  In the early days of DCC, all locomotive installations were hard wired installs.


In the case of factory installed, plug n' play and drop in decoders, the locomotive model has been manufactured giving consideration to future operation in a DCC environment.  For a hardwired installation no such consideration may have been given so, it is important that the motor be totally isolated from all other electrical contacts; failure to isolate the motor will cause a short circuit that will lead to decoder failure.

Different manufacturers use different terms to describe their locomotives as being a candidate for operation in the DCC environment.  In looking at the various manufacturer's websites, there are some common terms.

DCC Equipped  or DCC On Board means that the locomotive has a decoder installed and is ready for operation in the DCC environment.

In other cases, you will see a term as DCC Ready, which, presumably, means that this locomotive is equipped with a jumper plug so that it can operate on a DC model railroad.  For operation in a DCC environment, installation of a decoder is necessary.  You may also find that the circuit board for such a locomotive may have capacitors and resistors which should be removed for proper operation.  In this instance, the locomotive's circuit board has been set up so that the model will pass European electronic noise regulations.  

One manufacturer's statement example: "DCC ready means that the motor has been isolated and provisions have been made for the installation of a decoder.  In HO scale we also try to install an NMRA 8 pin plug to make decoder installation E-Z".

Terms such as DCC Friendly, DCC Compatible or DCC Capable are sometimes used but they have not been used consistently.  

If you are not sure about a particular locomotive's possibility of being converted to DCC, a quick online Google search using the locomotive description and the term "DCC" usually will bring up a relevant page concerning a potential model locomotive candidate.

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