Today, I tested the Modellbahn Union J00002, 8-way DCC switch decoder WD8K for two-pole switch drives with screw terminals.
www.modellbahnunion.com/HO-gauge/8-way-DCC-switch-decoder-WD8K-for-two-pole-switch-drives-with-screw-terminals.htm
​It performed very well with my Z21 and Tomix switches. The operation is reliable and smooth. The PCB is very compact and allows to connect eight switches.

A few years ago, I purchased this kit from World Kougei
プラシリーズ Nゲージ TMC400A モーターカー 組立キット
world-kougei.com/SHOP/6044380.html
It's a mixed ABS resin / photo-etched parts kit. It didn't look too difficult to assemble.
I started by doing some research about the prototype and found quite a number of photos and videos online. I was immediately attracted by the Totetsu white/yellow/grey livery, photos are available here:
mcdb.sub.jp/forums/topic/fhi_tmc400a_43_東鉄_4012/
I also found a video showing operation with two locomotives, and several sets of headlights and alert lights flashing. I decided to try to reproduce that scene. 

That's what the kit looks like.

​I started by applying an undercoat of Tamiya 87044 Fine Surface Primer for plastic and metal (white), on the photo-etched and resin parts. That seemed to give a good result, but as I will describe later, during the assembly the paint started to peel off from the photo-etched parts. That has been a huge issue. I usually use Tamiya 87061 Metal Primer, which works very well, I should have sticked to this one for this project too.

​Gluing the parts was supposed to be easy, but proved very difficult at first. I tried Tamiya 87182 Extra Thin Cement, which didn't work at all. Of course the Tamiya Craft Bond works but it is very thick, very slow to dry and not very strong. I ended up using standard CA glue, which works well but is too fast, no time to adjust the parts... Next time I will try Tamiya 87137 Cement for ABS.

Painting white and grey worked quite well. I then looked for the perfect yellow for the project. I tried AK11046 Radiant Yellow, AK11047 Lemon Yellow and AK11049 Fluorescent Yellow from AK-Interactive. These bottles include dispensers and the paint is ready to use with a brush or airbrush. I decided to go with AK11047 Lemon Yellow.

​I cut, weathered and pasted small rectangles of AE03 Metal plate anti-slip 90 for the sides.
www.finemolds.co.jp/www/list/listetc.htm
That was not too difficult to make and this is a nice improvement to the model. However, this made attaching the side fences much more difficult as I had to drill new holes for them.

I then started to experiment with LEDs for the various headlights. The plan was to make a small DCC decoder with 5 LED outputs, and connected the LEDs to it. 0402 Warm White LEDs for the head and tail main lights. 0201 White LEDs for the side lights. Various 0402 orange LEDs for the alert lights. I installed a total of 12 LEDs, and ended up with an unmanageable web of wires... impossible to solder to the DCC decoder.
I then decided to make another PCB just to manage the connection to the LEDs. That proved a good idea, but the whole thing is still very difficult to assemble and very fragile. Not recommended.

This is a photo of the EM13 decoder connected to the motor.

Anyway, I pushed through and made it work. So I now have 3 PCBs in this tiny cabin. The EM13 for the motor, the self-made DCC decoder for the lights, and another PCB right below the roof for connecting the LEDs. That's very difficult to manage. As I fell in love with that locomotive, I am now planning to redo it (next month, next year, or next life).
- The motor decoder is not necessary, the locomotive does not run well at low speed anyway, it would require at least a flywheel and a keep-alive.
- I plan to redo the lamp DCC decoder to fit it right under the roof and solder most of the SMD LEDs directly on the PCB, using 3D-printed light pipes. That would hopefully make the wiring much more manageable.

I needed to add more signals, so I made a new version of my Arduino Nano-based DCC signal controller. This one can control up to ten Tomix signals. 

I just upgraded to DCC my brand new Kato 10-1174 Shinkansen Series N700A “Nozomi” (Basic 4-Car Set). It is compatible with the Kato 29-351 EM13 (for motor control), Kato 29-352 FL12 (two units required, for the headlights) and Kato 29-353 FR11 (four units required, for the interior lighting). Very easy to upgrade.

Today I built a simple test/cleaning/DCC programming jig that I will use to program and clean my locomotives and trains. It has three tracks:

• A DCC programming track connected to the Z21 "Prog Track" output. I use it to program CVs in locomotive decoders.
• A test track connected to the Z21 "Main Track" output. I also include a TOMIX 6415 - Multi Wheel Cleaning PC Track. 
• A TGW Tsugawa N-gauge wheel cleaning kit. Very useful. It's made of two electrically conductive foam pads connected to the main track. It is able to clean locomotive wheels while they rotate.

I installed NGDCC DE28TLRK DCC decoders into two of my Kato Portram cars (Portram TLR-605 (ECO Green) Kato 14-801-8 and Portram TLR-601 (Red) Kato 14-801-1.
The NGDCC decoders can be purchased here:
http://www.snjpn.com/ngdcc/de28/de28TLRKj.htm​