Thursday, November 1, 2018

Tomix KIHA40-1700 `Nagamare`

Two years ago I was in Aomori (青森市), a city in the northern part of Tohoku region in the main island. I was walking to the Hakkodamaru Memorial Ship which is nowadays a museum, and inside the ship they have some of the trains that used the ferry to cross to Hokkaido. Passing by Aomori station I saw this KIHA40-1700 "Nagamare" and I loved the decoration. I added it to my collection as soon as Tomix announced the model:

It is the reference number 98022, a set of two cars. One car has the motor, while the other only lights. Each car has hidden switches to turn on or off the lights of each side:

Tomix models are perfectly built, but converting them to DCC is always tricky and everything must be disassembled. My strategy will be to solder single wires to each point (motor, lights, pickup current, ....) and after join this wires to the decoder:

Let's start with the motor, you have to remove the springs to isolate it and solder decoder wires to the tabs of the motor:

Once the motor is in place with wires soldered, the existing holes in the board must be enlarged to fit the wire:

And the same for the plastic piece with the seats to cross motor wires to the top:

Now the light board: I will have to turn one of the leds of each side to have the positive lead connected to the same side. Both positive leads of led must be soldered in the track having the resistor, and the negative leads isolated to connect the decoder wires (white and yellow).

You can see in the next photos how I cut the track to isolate leds, and the reversed led soldered again in place. You see I removed the micro-switches. Now I regret having done that because finally it was not needed and could be useful. So, DON'T REMOVE SWITCHES!!

I solder the wires to the led and also black and red wires to the points where to take the wheels current:

The board fits glued to the seats plastic part, so there is no room for any wire. All wires must cross this plastic piece and just a little bit of sanding was needed for a proper wire routing:

Test ALWAYS everything before soldering the decoder and putting it on tracks. With the tester in the diode position you can check that leds light on. Put the black end to the wire soldered to the led, and the red one to one of the black or red wires and check all lights. Check also there is no connectivity between red/black wires and motor wires (gray/orange):

So, time to solder the decoder and test it on tracks:

After checking it works, I tried to reroute wires as well as I could....

For the non motorized car I used a LaisDCC decoder. It costs less than 10€ and it is very convenient when used for lighting cab cars as it can invert the polarity so you won't need to reverse any led. On the other hand, I never use them to power motors as in my opinion LaisDCC decoders are the most horrible decoders to drive motors. Regulation is awful.

To use it for lights, use the grey and orange wires (not the function wires) and program it before soldering: set CV61=68 and write in CV133 the desired intensity (value from 0 to 255). Normally a value between 20 and 50 is enough.

Now is time to add all details, a watchmaker's job....

And model finished!!!!


  1. Nice job Dani, that's a great looking train.

    1. Thanks! I'm following your blogs from a log time ago, your posts are always an inspiration!