DRG Version 2 - KATO 10707

12/06/15- LocGeek's website made me aware of Kato's older "Flying Hamburger" railcar. This is another icon of rail history (gotta be, since Tuvalu issued a commemorative stamp!), from the same pre-WWII Germany as the Henschel Wegmann train, both streamlined to set speed records. The Flying Hamburger, Henschel Wegmann, and the Rheingold coaches all share the same purple and cream livery. Apparently, I'm a sucker for this kind of stuff: Once I learned of it, within a day, I'd tracked one down in a German eBay listing.

I looked forward to working on it because it was a diesel railcar: I hadn't configured any sound decoders for diesel before. My first electric locomotive sound car had been a pleasant surprise since I'd imagined that it couldn't sound as interesting as a steam locomotive.

Another selling point for me was that it had been made by Kato. I was aware that it was an older discontinued product, but based on my experiences, was willing to take the chance that it was a good candidate for DCC. If I have any apprehensions about getting Kato trains, it's that they're too easy: They're reliable and unquirky, so DCC installations are almost too uneventful to be interesting. For as many problems as I encountered with Arnold's Henschel Wegmann project, I can say in retrospect that it was an interesting and fun project. It's the only train in recent history that's stayed on my layout for over two months, and is run regularly (to make sure that it's still working!).

Preliminary Analysis: Apparently, this was made by Kato for the German market. Kato made two DRG versions, with the main difference being the painting of the nose-- Version 1 doesn't have the purple painted nose. The other two DB versions have a red livery, with slightly different roof details. As you can see, the interior lighting kit is similar to, but not the same as the current light kit. Based on the instruction sheet, this looked like an fairly straightforward DCC modification project:

  • There's plenty of interior space for a speaker and sound decoder.
  • The incandescent head/tail bulbs will be replaced with white and red LEDs but should be an easy swap with standard 3mm LEDs.
  • Electrically, it's very simple to wire for DCC since there's no circuitboard designed exclusively for DC operation. A noise-reduction capacitor is clipped across the motor leads, and the incandescent head/tail lights have diodes inline, but that's it.
  • The two cars aren't meant to be uncoupled so DCC connections can be hard-wired between the two. The center truck and articulated section's brass sliding contact power-sharing system can be simplified by wiring. This should have few negative consequences (wire fatigue, but no mechanical contact wear and surface oxidation between contacts).
  • The track power collection system looks good: The three trucks are widely-spaced with a needle-tipped axle design. This should provide reliable electrical power for the decoder and lights.
  • Although this is a streamlined railcar, the streamlining skirt has cut-out sections that swivel with the trucks, similar to the way that Trix and Marklin did their HO versions of the Henschel Wegmann coaches. Although it's probably not faithful to the 1:1 version, it gets past the design dilemma and angst that pervades Arnold's N-scale HW set.

Disassembly: Disassembly of the model is usually easy, but can be one of the hardest parts of a project. The goal is to do it without breaking anything. Usually, that means figuring out how the manufacturer assembled it so you can follow those steps in reverse. A detailed assembly diagram helps, as do photos and written descriptions, but I often find myself stumped about what do do next, and it's usually with modern products that are snap-fit assembled.

Older products assembled with screws are usually easier: You just have to find all the important screws and when you removed them, the parts usually disassembled with gentle pulling pressure.

Kato relies heavily on snap-fit assembly. Although the instructions and exploded view are helpful, disassembly of snap-fit parts sometimes needs a 3-D view; seeing what's on the underside helps explain how it's held together and how it works. The challenge is figuring out where to pry to release the locking tabs. In the case of this model, removing the obvious outer screws isn't enough to remove the upper shells: You have to pry between the edge of the upper compartment shell and the lower section to release the locking tabs and separate the two. That's an easy one, since that form of attachment is used by many manufacturers to secure body shells to the lower section.

Removing the Floorboard: Once you're inside, it's a different story. Some of it is obvious. Once you slide out the head/tail light units, the cream-colored floorboard looks like it should come out simply by splaying the side tab retainers at the front and back, the way Kato does most of their passenger cars. But it doesn't. There are clearly two hidden attachment points that secure the floorboard to the rest of the bottom section.

Although there are many ways to attach things like this (adhesive, c-rings, rivets, eyelets, etc.) there are two likely means of attachment for a Kato product: (1) plastic retaining tabs, (2) screws. If the floorboard is attached by screws, forceful prying is an especially bad idea. Current Kato products seem to use tabs, but you can't assume that if you intend to pry pieces apart hoping to release unseen locking tabs. Even with plastic tabs that are usually amenable to prying, you run some risk of breaking tabs if the plastic formulation isn't flexible enough or has become old and brittle. The best way is to access the retainer to verify, and if it's tab-assembled, apply a minimal amount of force to splay it.

Therefore, it would be helpful to remove the bottom plastic skirt frame to see how the floorboard is held. However, it's not obvious how to remove the plastic lower skirt frame from the cast weight frame-- remove the truck? Removing that isn't obvious either. In this case, I had no other reason to remove the lower frame or truck so spending lots of time on this would be a huge sidetracking!

Sometimes the best way isn't the only way. Plan B is based on observation and clues. Although you can't clearly see how it's assembled without removing the bottom frame, prying it just a bit, or peering through openings in the metal frame might give some clues as to whether you're dealing with tabs or screws. Splaying the bottom plastic frame and peering through an opening in the end of the metal frame, I saw white at approximately where the floorboard was attached. I therefore concluded that the floorboard was attached by locking tabs, and that they appeared to be on the sides.

Lifting the floorboard up with a sideways nudge didn't do the trick, and I was afraid to apply too much force for fear of breaking tabs. You really can't fix a broken tab (superglue, epoxy? nope!), and the tabs secure the floorboard and contact strips to the metal frame, which bring in the track power from the trucks, which is why Kato power trucks work so well... so keeping the tabs intact is really important!

Fortunately, there were manufacturing "breadcrumbs": Small divots on the underside of the lower plastic frame, on both sides of the cutout for the metal frame. They aren't cosmetic and aren't necessary to make the train run, so they're probably to help with disassembly. A blind locking tab doesn't need any special tools for assembly, but for repair disassembly, you want to unlatch the tabs without scratching or gouging plastic. The divots allow just enough room to poke a tool like a curved dental pick or small jeweler's screwdriver up into the frame from the bottom and splay the locking tabs, one side at a time (This is where it helps to know the orientation of the tabs). Once you've done that, the floorboard lifts out.

If you've followed this excruciating explanation, I apologize. The point is, tinkering and troubleshooting are all about common sense and reasoning: Knowing what to watch out for and looking for clues when the solution isn't obvious. Manufacturers design things for quick, efficient and cheap assembly, but often create a back door so they can do disassembly for repairs. Tab-assembled products are optimized for assembly and sometimes need special tools for disassembly.

Great. Removed the Floorboard. Now What? One reason to remove the floorboards is to let you remove the contact strips so you can solder wires to them without worrying about damaging the floorboard plastic. You can do this from the top without removing the floorboards if you're careful and fast with the soldering iron. What you don't want to do is damage the mountings that hold the contact strips in position for the trucks because that's an important ingredient in what makes Kato's power pickup work so well.

Removing the floorboard on the non-motor car lets you access the motor mounting space in the metal frame. For production efficiency, Kato uses the same part for both cars, but installs a motor in only one car. For someone who installs stuff in space-starved N-scale trains, the huge empty mounting space in the other car is like finding gold. Admittedly, it's not that big of a deal since the cabin interior is undetailed, and there's so much interior room to install stuff.

Detailing the Interior: Hiding the speaker in the space below and out of sight should give you the option to create a more detailed interior... or so you might think. However, the reality is that the floorboard is about level with the windows, so you can't put in realistic seating (with leg room), and almost anything you install that's not attached to the ceiling will be visible through the windows.

The empty motor space is big and easily hides a Sugarcube speaker with space to spare, but isn't long enough to hide a LokSound decoder (unless you mill the metal). So the decoder and its dense sprout of wires has to lie somewhere on the floorboard. The train is like a very short 2-car EMU so you can run head/tail lights, motor, and sound from a single decoder; however, that means that the head/tail light wiring is long, stretching from one end to the other.

You could probably hide some of that wiring clutter under the floorboard but that would make planning and assembly more difficult. Personally, I didn't feel it was worth it since there's only so much you can do to dress up the interior. The best you could accomplish was leave a clear view through the windows (Even without DCC wiring, the head/tail light assembly obstructs the first few windows). A simpler compromise would be to cover the windows with something translucent that hides the guts and allowed the windows to show illumination from interior lighting. (I didn't bother to install interior lighting because I was eager to test the train with DCC.)

DCC Head/Tail LEDs: The head/tail lights are one of the more challenging aspects of the conversion, because parts have to be replaced, rewired, and the remodeled assembly has to fit within the original space. (It's "more challenging" only because most other conversion tasks are so straight-forward.)

In DC operation, the color/direction change is handled by two lights and a light tube; the DC track polarity will conduct through only one of the two diodes at each end, which lets power through to one of the two incandescent bulbs at each end.

It's not much different in DCC. The main difference is that the track power isn't used to power the lights. Power and switching comes from the decoder: The headlight control line (ESU- white wire) from the decoder simultaneously turns on a headlight LED in the front of the train and a taillight LED at the rear of the train-- it's connected to both. The taillight control line (ESU- yellow wire) simultaneously does the same thing, but to the other two LEDs. The control lines aren't actually dedicated to "head" or "tail" lights; they're just two separate control lines that connect to the negative side of the LEDs. They're mapped to conduct current for forward or reverse direction changes, and to a function key for on/off. The common positive line (ESU- blue wire) has a 470-ohm resistor inline so the high DCC voltage doesn't fry the LEDs, and connects to the positive lead of all the LEDs.

Caveat: If the "on" voltages of the head and tail LEDs are significantly different, only one LED of the two connected LEDs will fire: A resistor inline with the earlier-firing LED should fix this problem. I used a 470 ohm resistor.

Because the track power isn't used for the LEDs, the stiff power leads that double as mountings to the floorboard are best cut off to remove the possibility of a short circuit to track power. Without these, the lower plastic housing will have to be glued to the floorboard.

Each LED assembly will have three wire connections (common positive x1, headlight control x1 and taillight control x1) to replace the power leads. Since the light tube/upper assembly housing and lower assembly housing/circuit board slide snugly over this when the train is closed up, some modifications (cut openings for the wiring) to the upper housing will probably be necessary. Naturally, tight-fitting parts rarely goes smoothly and easily when you're trying to put the thing back together to test it out.

DRIVING TEST: It's a Kato! It ran smoothly the first time it was placed on the track; the motor isn't the quietest, but it isn't objectionably noisy either. As expected, the power pickup was totally glitch-free, tested using the sound decoder as the glitch detector. Although it runs silky-smooth at crawling speeds, it's such a short train that I felt compelled to drive it like a race train, zipping around the track: I cured the urge by cutting the top speed in half through decoder programming.

I have no idea what this is supposed to sound like (and don't really care), so I found a diesel sound set that I liked at ESU's website (#54876, V180-BR118-R8) and installed it. Although it's a turbo diesel, it has a nice diesel startup and idling sound. A lot of diesel sound sets seemed to have a funky telltale digital algorithm when throttling up, so it took a while to find one that I liked. Basically, the turbo whine tracks with the throttle, overlaid on the heavier diesel/fan sound. I think it gives good feedback about speed changes without sounding too cheesy. It was so freakin' loud that I had to cut the volume of each of the drive sounds in half!