13/10/2019; 16/10/2019.

Electrification of couplings

Four wires must be distributed from one end of the train to the other: the common positive wire (blue in the DCC standard); the tail light control wires, white and yellow; and that of compartment lighting control, green. So we need four-pin connectors. Their necessary miniaturization made me choose 1.27 mm pitch connectors, male and female.

This photo shows the attachment of the male part on a drawbar. The two central pins are bent at 90° and inserted then glued into holes drilled on the bar, for mechanical strength.

Male connector on drawbar

The problem of these connectors is that the pins don’t hold well especially after heating when soldering the wires. Being aware of this, I made tiny PCBs (0.8 mm thick) to strengthen the connectors, both male and female.

Connector’s PCB

The drawbar below is purposely dislocated, so a little out. The connector actually hardly exceeds the bellows plane. You can see the connector PCB by passing the magnifying glass on the photo. Note that the PCB simply replaces the original plastic holder, which is removed after soldering. The purpose is to allow keeping long enough pins.

Male connector on drawbar

Hover over the picture to zoom.

View of the female connector, soldered directly in the air on the wires.

Female connector in the air

Hover over the picture to zoom.

Note: the wire colours are not respected, because I did not have at this moment all the necessary colours. I had even started to wire everything in black, for discretion, but there was too much risk of error.

Problem of the passage of the equipped drawbars under the bellows

Although the connectors are small, they hinder the rotation of the drawbars by rubbing under the bellows. It is therefore necessary to mill them, the fixed part on a height of 1.1 mm and a length of 4 mm (red arrow), and the bottom of the bellows over almost all its width, and on a height of about 2 mm (green arrow).

Milling the bellows

Concerning the dummy, it is also necessary for the same reason to mill the back of the zamak chassis (red arrow). This is done quite easily. Soft file finish.

Milling of the frame of the dummy

Finally, to facilitate uncoupling, I softened by a few file strikes the clips of the drawbars, female connector side. Thus, at the time of separation, the drawbar remains attached to the coach male connector side, which is not likely to pull on its wires and tear them.

Softening the drawbar clip

One last remark. Connecting the connectors would be easier if they were placed below the bar, not above, as I did for the Roco RGP. But here, chassis returns under the couplings did not allow this.

Some pictures of the coupling between two coaches. In the first, we see… that we see nothing!

Attelage en fonction

Attelage en fonction

Female connector, pitch 1,27 mm
1 row of 4 contacts,
Ref. DS1065-01-1X4S8BV,
£0.11555 per 20+ (excl. taxes) — price 2019
at TME

Male connector, pitch 1,27 mm
1 row of 4 contacts,
Ref. 741104,
£0.0711 per 25+ (excl. taxes) — price 2019
at TME