Converting Tomix MU Trains to DCC

[Gilshrat]

Hello everyone. I am new to this blog and Japanese model railroading, but am hoping to get some info on converting Tomix MU trains to DCC. I was a pretty avid model railroader back in the States with extensive experience using DCC on both my home and club layouts. I recently moved to Japan and have become interested in modeling Japanese N gauge trains. I have decided to upgrade my trains to DCC and am wondering if anyone has had any experience converting Tomix MU trains to DCC. I see that Digitrax makes decoders specifically for Kato MU trains (Kato 29-351 and Kato 29-352) can these also be used for Tomix. I know they wont be as "plug and play" friendly, but it looks like the functionality would be the same. Just might require some hard wiring.

 

I have two Tomix models I would be converting:

 

Tomix 92355 (JR Series 0 2000 Tokaido/Sanyo Shinkansen)

Tomix 98930 (JR 183/189)

 

Any information/advice would be appreciated.

[Kiha66]

Welcome to the forum Gilshrat!  Tomix models are not decoder ready, but they can be converted with a little effort.  While I have not done so myself, from what I understand the model has two springs under the floor connecting the motor to track power.  If you remove this you can wire a decoder in relatively easily, although you may have to add a small hole in the floor to route the wires.  A forum member mentioned working on drop in board replacement decoders, but I don't believe there has been more progress mentioned recently.

[chadbag]

I have not done that particular Shinkansen but did do the paper car of. Tomix N700 Kyushu train.   Look for my post where I describe how i did it and see if your motor car is set up

similarly.   Non Shinkansen may be set up similarly.  While I have some non Shinkansen Tomox EMU I have not yet tried to

comvert.  I don’t expect them to be too difficult.   Any wired decoder should work.   I used a very small digitrax in my Tomix Shinkansen and have settled on D&H Decoders for most of my other needs except where the KATO dropin decoders are specified. 

[chadbag]

I have not yet done cab cars.  I will get around to it eventually. 

[kvp]

I would suggest using Digitrax 7 wire decoders instead of Kato ones as they are smaller and come with wires attached.

 

For conversion, there will be two types of cars, motor cars and cab cars. For some models these are combined. The motor cars need the motor isolated from the main pickup brass strips and the decoder connected between them using the two track and motor wires.

 

Cab cars are trickier as they usually have small bipolar headlight circuits also connecting to the main pickup strips. You'll have to convert these from two wire bipolar to 3 wire pull to ground (blue wire: power, white: headlight ground, yellow: taillight hround) by connecting the power to the common resistor side, flipping one of the leds to have both leds light up towards the other side and splitting this low side into two so the head and tail light wires could be connected. The tail cab car (using the default forward direction on the motor car) needs the yellow and white wires swapped to have opposing head/tail lights on the two cabs.

 

Personally i would suggest getting spare  headlight boards for this, so you won't ruin your original ones in case of a mistake.

 

ps: The same procedure applies to Kato and other brand's non DCC ready trains. Some older models and locomotives use split frame motors, where you have to mill/file some space for the decoders.

 

I also suggested getting wired Digitrax decoders as they are shrink wrapped and can't accidentally short to any metal parts. The Kato ones are also made by Digitrax, just have a different form factor for plug and play install into DCC ready Kato trains.

[Gilshrat]

OK thanks for all the info. I have also been looking at the DZ126T as a very small decoder to fit in the trains. Anyone suggest a good online retailer to buy the docders in Japan. Ive found a limited selection on Amazon.co.jp and there is always the USA sites that ship internationally, but I don't want to have to pay for international shipping and customs if I don't have to.

[chadbag]

The Digitrax DZ126T is what I used in my Tomix Shinkansen.  I have a couple more I will be using in other Tomix Shinkansen I have, for the motor car.  I have yet to attempt a cab car.  I have some D&G FH05B for that but you probably won't find those in Japan easily.  Not having done it, I am not sure what the best choice would be for cab cars.

[Martijn Meerts]

Motor cars are pretty straightforward, and there's plenty space for decoders in them. Which brand you go for doesn't matter that much, really depends on what features you want. For example, Digitrax obviously has transponding, whereas Lenz and ESU for example use Railcom. Cheap decoders also tend to have very few control over the motor output, which in N-scale could be an issue. I have some trains that require fine tuning the motor control before they run smooth, many decoders don't have that. I've found the ESU LokPilot to have great motor control finetuning.

 

Cab cars is always a bit of a surprise to see what kind of LEDs they used. Tomix usually uses 1 white and 1 red LED, so in those cases the cab cars aren't an issue either. MicroAce on the other hand sometimes uses dual color LEDs, where they have white and red combined in 1 LED. Those can be a bit tricky, although several brands have decoders specifically for those kind of setups.

 

 

[kvp]

2 hours ago, Martijn Meerts said:

Those can be a bit tricky, although several brands have decoders specifically for those kind of setups.

I think many people (including me) would be very interested to know which N scale decoders support bipolar head/tail lights off the shelf?

[Martijn Meerts]

Capt Oblivious made a list some time ago, unfortunately the formatting went bad when we moved to the new forum software, but from his list the following are bipolar:

 

TCS M1

TCS Z2

Lenz LF101XF

NGDCC DF12r3

NGDCC DF11r3

 

Now, I don't know if these are still available, or if they're N-scale or not. But I do know that the latest version of the Lenz Silver+ Mini can be toggled between motor decoder and bipolar function decoder. In function decoder mode, the motor outputs (orange and grey) act as bipolar light outputs instead.

 

[kvp]

1 hour ago, Martijn Meerts said:

Now, I don't know if these are still available, or if they're N-scale or not. But I do know that the latest version of the Lenz Silver+ Mini can be toggled between motor decoder and bipolar function decoder. In function decoder mode, the motor outputs (orange and grey) act as bipolar light outputs instead.

Thanks! The Lenz LF101XF is based on a motor decoder with a software for bipolar lighting functionality instead of motor output. The Silver+ mini is probably the same but has the software for both modes. This could actually help many people as it allows to avoid modding the headlight circuits in japanese trains and for some trains, by adding double sided pcb connectors between the horizontal brass pickup strips and the headlight contacts allows a removable plug and play solution these non DCC ready trains.

[Martijn Meerts]

Yeah, the only issue is that motor decoders are usually more expensive than function only decoders. On the other hand, since you don't have to modify the light boards at all, it saves time and the light board is of course still usable if you decide to remove the decoder.

 

You do have to make sure you get the correct version of the Silver+ Mini though, it's a feature they added to it at some point (well over a year ago), without giving the decoder a new name of version number. Some stores might still have older decoders in stock. It is possible to update the firmware to unlock the feature, but you'll need the Lenz Decoder Programmer hardware for that.

 

Also, just noticed the Lenz Standard+ V2 also has the function decoder toggle. It's a (much) bigger decoder, but probably also a bit cheaper.

[kvp]

3 hours ago, Martijn Meerts said:

Yeah, the only issue is that motor decoders are usually more expensive than function only decoders.

You need a full H bridge for bipolar push-pull operation and that means a motor driver chip, so this is pretty much given. Not having to modify the light board in a control car is imho worth it, especially in case of bipolar leds.

 

Another good alternative would be to add the H bridge chip on a separate circuit board (H bridge, two diodes and two resistors), which could even allow motor and bipolar head/tail light operation, but it would need a custom circuit, which is imho not really worth it.

 

ps: Imho the decoder list should be made a sticky post somewhere, it could save quite a lot of trouble for many people.

Edited May 2, 2018 by kvp

[Martijn Meerts]

The list needs some reformatting, and is probably not very up to date anymore, but I'll see what I can do.

 

Edit: Installed a plugin for the text editor so that we can use tables now, and reformatted the decoder list table. Some info went lost because I wasn't sure which column it belonged to, but should be relatively easy to find again.

 

The thread is actually already a stick in the DCC forum: http://www.jnsforum.com/community/topic/673-dcc-decoders-for-cab-carsend-cars/

 

Things like that might actually be a good candidate to turn into an actual page on the forum rather than just a topic though, I'll have to look into that a bit more.

 

[Gilshrat]

So I finally converted over two Tomix Shinkansen 0 series trains. I made a video of it on my YouTube Channel. I may not have done the conversion using best practices, but I think I came up with a good work around that allowed me to use standard decoders for the end car lights.

 

 

Edited January 9, 2019 by Gilshrat

[Kiha66]

Nice job, thanks for making the video explaining how you did it!  Smart idea to use the speed table to make constant brightness head and tail lights.

[JR 500系]

Oh wow that is a good video about showing how to exactly DCC a typical Japanese EMU model train! It certainly enlighten a DCC noob like myself! Very cool indeed! Would extra work be required also if one were to add in interior lights?