Wednesday, April 24, 2013

Tomix Cleaning Car Digitalization

First of all, I have to thank the help posted for this digitalization to the Agenz people (see their article), and all warnings from Quinntopia after he burned at least one of this (see the posts). Thanks to these people my digitalization went straight forward. 

My first advice is to use a really tiny decoder. I first tried Digitrax DN135D, with measures  13,86mm * 10,3mm * 4,83mm, but it was still too big to fit in the weight hole. Finally, the only suitable decoder that I found was a Digitrax DZ125 (10,6mm * 8,7mm * 2,86mm). Even with that small size, I had to trim the protector to fit it in.

Step 1: dismount the cleaning car starting by removing the screw of each bogie. You can also pull the rounded plastic part in the bottom that acts as a vent, but I think is safer to do it later polling from the motor. With the screws removed, lift the plastic covers and the weight inside. Last, pull from the motor and remove the circuit board:

Step 2: remove all electronic components from the board and discard the plastic piece that goes in the hole of the board and it's connected to the switch of the top cover used to change the motor speed in analog mode.  Once the board is clean, it's also recommended to cut it a little bit to help decoder to fit inside. Be careful you don't cut it too much (just a pair of millimeters) or you will loose the part where it takes the current from the wheels.  

Step 3: Prepare the decoder cutting the wires and tin them (see the right position in photos below). I recommend also to use a good "wire trimmer" (sorry, I don't know the exact name of this tool in English...) because decoder wires are really weak.

Also apply tin in the following points were you'll solder the motor and power wires. I use very thin tin, much less than 1 mm (I think this is 0.2 mm), or the tin drops will be too big:

Step 4: Solder the decoder!! In the photo below you can see the exact position and where each wire goes. Of course you can cut the function output wires, but I want to keep them to try to put a flashing light or similar:

Recommended: Isolate the board as you see in the photo. I think it's not really needed, because current tracks of the board don't touch the metallic weights (those metallic weights are powered from the tracks), but it's always worth being prudent:

Step 5: And now you can mount everything again. The only pieces to discard are the switch of the board (I mentioned before) and you can also remove the top case selector, but do it carefully because this part of the hull is where the screw is fixed.

I removed the selector because I wanted a blinking light when the cleaning car is active and running in the forward direction. Yes, not beautiful... but I hadn't at this moment SMD leds nor resistors, so it will do the job. Finally, it's just a cleaning car, not a prototype, and inside there isn't room for anything else I guess....

 I hope this guide helps you to avoid buying special NEM boards for this car that in my opinion don't help to fit a decoder inside, just the opposite!!


Monday, April 1, 2013

DCC Physical Schema and Connections

Let's see my installation from a lower level. You could see the logical schema in my previous post, and now I'll explain how is everything connected in a more physical view:

The most important connections are the following:

GCA101 and PC

That's a standard plain (not crossed)  Ethernet cable, with RJ45 terminals.

GCA101 and Intellibox

GCA101 has two RJ12 connectors for standard Loconet modules or devices. Here is where you will connect Intellibox. But remember to remove both jumpers from GCA101. These jumpers must be removed always if you connect an "active" loconet device (Intellibox, Twincenter, or any other central station supplying current or Railsync signal to loconet bus).
For more security, I suggest you to make a special Loconet cable without connecting pins 1 and 6 (the outer pins of RJ12). The other wires are connected pin to pin (2 to 2, 3 to 3, ..). You can also take an existent Loconet cable and cut the outer wires.
The correct connector to use in Intellibox is Loconet T. The other Loconet B is used to connect to a booster if necessary, because it provides the railsync signal.

GCA101 and standard Loconet Modules

If you are mixing standard Loconet Modules (from Uhlenbrock, Digitrax or any other brand), they can be connected to the remaining RJ12 connector in GCA101. One is occupied with Intellibox (or any other central station), and the other is the starting point of your standard RJ12 Loconet bus. Just use standard and plain (pin-to-pin) RJ12 cables.
Standard modules can be connected also to Intellibox Loconet, but it's much better to keep the central station just to move and give orders to trains. GCA101 has much better processor power to manage messages than the central station.

GCA101 and GCA50

GCA50 also shares the Loconet Bus, but it uses a different connector. Standard Loconet buses use RJ12 (telephone connectors) as said before, but having only 6 wires you cannot carry all signals. That's why Intellibox has two different Loconet connectors:

  • Loconet B: Carries Loconet signal plus Railsync in the outer wires (pins 1 and 6).
  • Loconet T: Carries Loconet signal plus 12V (pins 1 and 6) but you haven't Railsync signal

Using a DB9 connector (the same used for RS232 in PCs), you can carry all signals and power to the modules. GCA101 has two of these connectors from where you extend Loconet bus to all your existing GCA50.

Standard full wired male to female 'extension' Rs232 cables can be used, but it's not recommended because they cannot carry all the 3Amp. power from GCA101. The best way is to use Ethernet Cat5 wire with the following pinout:

DB9 PinLocoNet functionEthernet cable colour
1GNDblue + blue/white
2Railsync -orange/white
3Loconet signalgreen
4Railsync +orange
5+V supplybrown
7n.c.not connected
8n.c.not connected
9+V supplybrown/white