Is it "DCC Ready"?

To fully utilize a DCC system, a model train locomotive (or other powered vehicle) needs to have a DCC decoder installed. The usual way of describing this is to refer to the model as "DCC Equipped". But what about a model that doesn't have one, did the manufacturer make allowance for this at all, or is it going to be a job for an expert? It would be nice to know that a locomotive is ready for DCC. And some models are described by terms that seem to imply this.

But what do terms like "DCC Ready", "DCC Friendly" and "DCC Compatible" actually mean? Different things to different people. The intent of labels like this is to make DCC more accessible to ordinary modelers, but all too often they achieve the opposite by making something fairly simple hard-to-understand.

DCC isn’t very big in Japan yet so no models today come equipped with decoders from the factory. That lack of interest seems to be gradually changing, but of the major manufacturers only Kato sells locomotives that can even take a drop-in decoder. Also, due most likely to the small space available in passenger trains for electronics, Kato’s “DCC Friendly” passenger trains require a custom decoder and do not use a standard socket to connect it to the motor, pickups, or lights. This either takes the form of a replaceable lightboard (in locomotives) or separate drop-in circuit boards for motors, head/tail lights and interior lighting (in multi-unit passenger trains). Both of these kinds use a simple friction-fit mounting, where brass strips press against contact pads on the decoder to connect it to the power supply, motor, or lights.

Unfortunately, Kato’s not alone, in that there is no multi-vendor accepted standard for how to describe a locomotive that comes equipped with a decoder, or ready for one. The NMRA standard doesn’t define a term for either, and specifically it does not state or suggest what “DCC Ready” means.

I’ve seen “DCC Ready” used to mean “has decoder installed”, or “has motor isolated from frame”, which are the two extremes of the range of “installation can be done by someone other than an expert” configurations. However, the typical use is to mean “compatible with a decoder but not equipped” or more specifically “equipped with an NMRA ‘recommended’ socket, but the decoder is not installed”. This is complicated by the fact that there’s more than one kind of socket recommended.

The NMRA (RP 9.1.1, PDF) defines small (in-line, 6-pin), medium (8 pins in two rows of four) and large (4 pins in a square block, offset) “recommended” sockets. The small is for N-scale, while the others are for larger scales. However, “DCC Ready” in the U.S. is often interpreted to mean “has 8-pin socket”, since HO is so common here. In Europe, “DCC Ready” is more commonly read as “has a NEM 651 6-pin socket but no decoder” (European manufacturers tend to identify the sockets by their NEM numbers: 651 for the 6-pin, and 652 for the 8-pin, although these designations aren’t used by the NMRA).

Given that ambiguity I’m going to avoid using “DCC Ready” at all.

Rather than use something vendor-specific, or invent my own nomenclature, I’m going to adopt a six-level scale someone else thought up, converting it into a “DCC difficultly” scale of 0-5 (where 0 means “equipped” and 5 means “incapable”) to avoid use of the descriptive phrases (like “DCC Friendly” which conflicts with Kato’s usage). Since there are some quirks to Japanese locomotives that the original creator may not have known, I’ve adjusted the wording slightly to account for those I’m aware of.

cf. "DCC Readiness: Comprehensive Decoder Installation Standards," by Ron Beardon, N-Scale Magazine, November/December 2006, P. 47. As cited on this website, note that the numeric scale is my addition.

DCC Difficulty Scale:

0: The decoder is pre-installed.

1: There is provision for a drop-in circuit board without any disassembly of the mechanism; this may mean use of a standard socket, but also includes replaceable lightboards accessed via a removable body and similar solutions. Kato’s “DCC Friendly” Japanese locomotives mostly fit this category, as they use a replaceable lightboard (however some require modifications to the LEDs, which may make them category 3).

2: There is provision for a drop-in circuit board but disassembly of some kind more complex than removing the body shell is required (but not wiring/soldering); again this may mean use of a standard socket, but also includes replaceable lightboards (without modification) and similar solutions. Kato’s “DCC Friendly” passenger trains fit this category, as they use a hatch and a slot accessed by removing one of the trucks.

3: Some soldering and wire cutting required, but the motor is isolated, no new wiring is needed, and the work is relatively easy. This class includes drop-in circuit boards requiring minor modification as well as minor changes to non-visible parts of the body. Many Japanese models fit this category, although Tomix locomotives have a reputation for being harder to convert to DCC. Note: Kato passenger trains that aren’t “DCC Friendly” almost always require isolating the motor, but as this can be done simply with Kapton tape or a strip of plastic glued between the motor pickups and the power rails, such cars are classed as 3 rather than 4.

4: Installation can be done, but it’s going to require significant work, such as isolating a built-in motor from the chassis, milling the frame, or difficult routing of wires. Also included here are models where the decoder or lightboard need significant modification (such as adding or repositioning components other than large LEDs; e.g., soldering surface-mount LEDs or resistors). A space-constrained environment such as a tram may cause problems. Kato’s M250 Super Rail Cargo train falls in this category, as the decoder has to be placed in the cargo container on the motor car, and wires routed from there to the motor and pickups.

5: “You can’t get there from here.” Installation is impossible due to space or design without something as drastic as a complete rebuild of the frame or mechanism.