G’day everyone, This is my first attempt at a “how to” , I hope it is helpful to collectors of Tomix Japanese trains who want to run them with DCC. I am using the TCS M1 decoder. I have not tried the Digitrax DZ125 yet but I think it would fit. For now I am just concentrating on getting the motor cars in my fleet done, then I will go back and do the end cars. If this is helpful I will post other decoder installations. Let me know what you think. The mill I use consists of a cross slide vice mounted on a floor standing pedestal drill and the milling bit is a 3mm 4 flute end mill. This first install is into the Tomix chassis part number 2824, this is located on the bottom of the chassis. The following trains are the ones I know of so far that use this Chassis. 92929 100 series shinkansen Last Run memorial set 92639 300 series shinkansen 92277 700 series shinkansen Hikari Rail Star 92274 E1 series shinkansen 92228 923 Dr Yellow Let’s get started then. Here is what we have once the shell is off. Remove the rubber insulating sheet. This is the chassis stripped bare. We won’t be needing the small capacitor anymore. This shows the rough position of where the TCS M1 decoder will be. My milling setup. The yellow circle on the vice is a thumbscrew for adjusting the friction, this one is for left/right. There is another one on the side for fwd/backward. Do these up a bit to stop the vice slides moving from vibration when the drill is running.
part 2 Use this ring to set the depth. Don’t try to do this in one pass, I use 2-3 passes. Make sure the chassis is sitting flat in the vice. Here the ridge on the side of the chassis is sitting on top of the jaws on both sides. Here I am setting the depth for the first pass. It is a bit hard to see from this angle, but the bit is approx 1.5mm below the top of the chassis. This shot is just to give you an idea of the first cut depth. This is the finished product. As you can see, I have broken through into the driveshaft tunnel a little. I aim to get the decoder sitting flush with the top of the hole we have just milled. Sometimes I break through, other times I don’t. It is not really an issue, but I would not go any lower than this otherwise the decoder might rub on the shaft when everything is back together. Just keep using the decoder to check the depth as you go and you will soon get a feel for it. The finish looks a lot worse than it really is because the camera is on macro.
part 3 Make the slot a little wider than the decoder to allow the motor wire to pass down the sides. Next I Dremel out these shallow channels for the power wires. They only need to be about half a wire deep, the ridges at the edges of the chassis provide the rest of the depth. Chamfer the channels where they lead into the decoder cavity. Also chamfer the vertical edges of our new decoder cavity so the motor wires can get around the back of the motor, you’ll see what i mean in a later photo. While you have the Dremel out, smooth out all the sharp edges created by the milling process. Clean out all the swarf before going any further. Now clean it again just to be sure. We will be cutting down the motor contacts. Cut the contacts so they are about half way up the slots at the top of the motor. This gives us a bit extra room for the wire. I cut off the function wires level with the heatshrink. Here you can see the yellow and blue, the white wire is on the bottom. I always use decoder pro to disable the function wires under dcc and analog control.
part 4 Here I am measuring up the motor wires. I cut the orange and gray at the middle of the motor as shown by the pin. You can also see the chamfer I was talking about earlier where the wires go from the decoder cavity into the motor cavity. Tin the wires and the contacts before soldering them together. We don’t want big blobs here because it will stop us getting the little spacer back in later. Solder the wires right at the top of the contacts. I use silicone to hold everything in place. Putting the spacer back in. Use a pin to hold back the contacts. Now you can see how it all fits. Any excess motor wire can be tucked down the sides of the motor.
part 5 Put the rubber insulator back on. Clip the floor back in. This photo shows the red power wire sitting in its channel. Make sure the wires exit the chassis at these little slots in the floor. Make sure the wires are right against the sides so they don’t get in the way of the pickup springs on the trucks.
part 6 Cut the wires at the opposite diagonal corner of the brass strip. This shows the wires and brass pickup strips tinned. Use a small tip and make sure the iron is hot so you don’t melt the plastic. I only spend about 1-2 seconds on each brass strip. Make sure the iron and brass are clean so the solder takes as fast as possible. Use tweezers to hold the wire and again be as fast as you can. This should only take ½ -1 second each. All done. Nothing is visible once the end goes back on. Program to your liking but don’t forget to disable the function wires in both dcc and analog. I hope this is useful. If anyone knows of other sets that use this chassis, let me know so I can edit the list at the start.
Mrpig - this is a really informative tutorial. I know a lot of other modelers that are having problems with installing decoders in Tomix trains especially the earlier models. Thanks. I'm also sending you a PM
mrpig, great thread! Even though I don't have this type of loco, I appreciate the time it took you to take pics of your progress and write it out. Hopefully the admins will add this to the How To page -Mike
