Tomix C57-135 decoder install

[Martijn Meerts]

So, with 1 decoder left from my latest batch (I really need to order some new ones, but they seem to be constantly sold out at the moment), I figured I'd go ahead and try the locomotive I've been wanting to convert to DCC for a while. It's also one of the locomotives I feared the most, considering the motor is in the boiler, and the detailing would mean having to be very careful.

 

The first issue was opening up the loco. I'd looked at it before, but couldn't figure it out. Turns out it's rather easy, the driver's cab is clipped on separately from the rest of the shell, so I took that off first. After that, the shell is really just clipped onto the frame. It only just barely fits on, so it feels like it's stuck somewhere when trying to take it off, but a little careful prying got the shell off quite easily. After that, the motor is clipped into a plastic frame, and the frame is clipped onto the metal frame. The whole drive train is also held in place by clipped on plastic clamps, as is the light board.

 

The tended has 2 screws in the bottom that hold the bogies to the tender. These screws also hold the entire tender together. The tender is rather intricate in it's construction, and is built up out of lots of parts. The tender also has it's own light board.

 

 

There are a few things that need to be decided. The obvious one is where to put the decoder. I think the only option is in the driver's cab, considering there's really no room inside the boiler, nor is there enough metal frame to cut away to make room. A really small decoder might fit in the little hump on the train, but that means leaving out a bit of weight, and considering the locomotive isn't that heavy to start with, that might be a bad idea. A somewhat possible option would be to hide the decoder inside the tender, but that would mean you'd require 4 wires between locomotive and tender. The coupler between locomotive and tender is too intricate to make a custom coupler.

 

Another problem, is the light inside the tender. To control it, there have to be 2 wires run from the locomotive to the tender. Normally it's not much of an issue, but considering the high level of detail of this locomotive, the wires might stick out too much. The obvious solution would be to hide a function decoder inside the tender that controls that light. This does require cutting away some plastic here and there though, and that in combination with the additional cost of a function decoder might not make it worth it for a simple light that won't be used most of the time... Plus, most other steam locomotives have no light in the tender either. (On the other hand, I really do prefer keeping all functionality in a train when converting to DCC.)

 

Also, running wires from the front head lights in the locomotive is challenging. Regular decoder wires won't work, because the shell wouldn't fit anymore. Another thing to be careful of is that the wires don't touch the flywheels. I'll probably end up using thin, lacquer isolated copper wires, and route them alongside the frame, glueing them to the frame at certain spots.

 

 

More pictures once I figure out (some of) the above problems and actually get somewhere with the install ;)

 

 

Image 01:

The C57-135 in bits and pieces. Notice the amount of parts of the tender.

[Bernard]

Boy, Marti....you really like a challenge!

(and I thought the Kato C57 would be hard)

 

I look forward to see how you approach the install.

[Martijn Meerts]

Bernard, the idea is that all my trains get a decoder sooner or later, so there's going to be some challenges now and then =)

 

As for Kato's C57, it's not a difficult install, the problem is getting a decent connection to the frame/power pickup. The first C57 I did, I drilled holes, tapped those, and used tiny screws to solder the wire to. It worked great, but was a *LOT* of work. The second C57 I did, I decided to modify the light board and use that for power pickup. That meant running quite a few wires (the 0.02mm lacquer insulated ones) through the entire locomotive, but it was much quicker than the whole drilling/tapping idea. Another disadvantage of tapping is that you need a really small tap, which are terribly expensive, and break real easy.

 

 

 

Anyways, back to the Tomix version. I decided to go for 2 decoders rather than run wires from locomotive to tender. Wires would've worked just as well really, and they'd hardly be visible considering the design of the model. Only problem is, I didn't have a function decoder for the tender, so for now I've only finished the locomotive. I removed the light board from the tender temporarily until I get some new function decoders.

 

The install took a LONG time, and I had to make some minor adjustments to the shell. I do believe the locomotive is a bit noisier than it was, so I may have done something wrong when putting the thing back together. I'll have to check that at some point. The problem is just that it's a bit difficult to get the shell off now that everything's installed. I need to find a good way of taking off the shell and motor simultaneously, otherwise I have to de-solder and re-solder the wires to the decoder each time :)

 

 

 

Image 02:

Motor and it's harness. The motor has really tiny tabs to solder wires to, so a small tip is definitively recommended ;) The harness can be used as power pickup, you just need to make sure the copper tabs are insulated.

 

Image 03:

The light board. I removed a small capacitor where the green block is, cut the copper traces at the red lines, and replaced the existing resistor with a somewhat heavier one at the blue arrow. I then soldered a wire to the anode side of the LED, before the resistor (decoder blue), as well as a wire to the cathode side of the LED (decoder white.)

 

Image 04:

Routing the wires from the light board to the front of the train, stage 1. The thing to keep in mind here is that the wire doesn't touch any moving parts, especially the flywheels. They'd scrape off the lacquer insulation layer on the wire in no time.

 

Image 05:

Routing the wires from the light board to the front of the train, stage 2.

 

Image 06:

Routing the wires from the light board to the front of the train, stage 3.

 

Image 07:

A collection of wires. I've used 0.02mm lacquer insulated wire for everything, so I had to mark them somehow. I just used a marker to draw some lines on the wire ends (1 for red, 2 for black, 3 for orange etc.).

 

In this image, 1 is red, 2 is black, 3 is orange, 4 is grey, 5 is white and 6 is blue. 5 and 6 are the ones coming from the light board.

 

Image 08:

Top overview of the routed wires.

 

Image 09:

Side overview of the routed wires.

[Martijn Meerts]

Image 10:

Initial testing to make sure there's no shorts etc. Obviously I checked for shorts manually before putting it on the track, but I always like testing on the track before I start shortening the wires and closing everything up.

 

Image 11:

The shell still fits like a glove. I had to drill 2 small holes in the shell to get the wires to the decoder in the driver's cab.

 

Image 12:

The holes with wires coming through them. They're 0.5mm holes and are barely visible.

 

Image 13:

Wires shortened. The copper wires are stiff enough to keep the decoder in place. Here it's trying to act like the driver's cab, and failing miserably ;)

 

Image 14:

Before putting on the cab, I painted the wires black.

 

Image 15:

The cab didn't fit anymore, so I had to cut off a bit of detail that was sitting on top of the boiler (they were just some simulated instruments, nothing noteworthy.) Also notice the black "tubes" I used to route the copper wire through. These are just stripped off insulation bits from a regular wire. It looks a lot better in real life than on the picture... Actually, with the cab on, you won't see them at all ;)

 

Image 16:

The locomotive put back together, with no visible decoder or wires anywhere in sight. (And yes, it's a TGV shell in the background ;))