Installing a DCC decoder and lighting in a Hornby Class 66

Click on each image for a more detailed view.

This guide has been provided by Mike Nencini, to whom we provide our thanks, and was first published on the Your Model Railway web forum.

Class 66 wiring diagram

Some while ago I acquired an EWS Class 66 from Hattons at a bargain price.  Although it was DCC ready it had no lights and the old Hornby tension lock couplings.  It has been sitting on the workbench shelf until I decided to take a break from scenic work to see what I could do with it.  What follows is the work carried out to install lighting, replacement couplings are for another day.

The decision was made to use a TCS T6X decoder I had available and independently switch the top light and headlights.  At the moment I don’t see me running night time scenes (enough to do just getting my layout functional at a basic level!) so I restricted the headlights to daylight working and blanked off the nearside headlight.  I fancied having a go at including the running lights and to include night running headlight switching would either have meant an additional two decoder functions or doing what manufacturers do and put a miniature slide switch under the loco to direct the decoder switching between day and night running lights.

So, with all that in mind here is my wiring diagram.  You will see that the running lights are lit via two strands of fibre optic cable (available in various diameters from DCC Supplies) illuminated by one ‘Prototype White’ Tower LED.  These are the type recommended for older locos, including steam lanterns as they give a soft, slightly yellow light.

The small boxes with F0, F1, F2 etc refer to the cab control functions that switch that light on/off.  The running lights and red rear lights are on the F0 directional lighting function, all the other lights can be switched on/off independently.

Class 66

The big challenge with this loco as will see from this picture of the cab front is that the light clusters are attached to the body work and slide down tightly against the front of the chassis.  This left no room to attach LED’s to the body.  One solution would have been to detach the light ‘boxes’ and cement them to the chassis but I thought cutting them out would be risky. 

Class 66 Class 66


My solution was to drill pilot holes through the body and chassis while still assembled and then remove the body and open out the hole to take a short stub of fibre optic which would then act as a lens when lined up with the LED mounted in the chassis.  See the two pictures alongside.  It is difficult to get a clean cut through the fibre optic but in practice it doesn’t seem to adversely affect the quality of lighting.

Class 66 fibre optic


The running lights are very small and rectangular!  This meant filing a short length of fibre optic to fit the opening – plenty of patience required. 

Class 66

At this stage the holes in the body work look a bit of a mess but the close up photograph doesn’t do it any favours and with a bit for careful touching up and some discreet weathering it will look fine on the track.  You will understand by now I’m a pragmatist about such things rather than a fine scale modelling fanatic.

Class 66
The first lights to go in were ‘Bright White’ 1.8mm Tower LEDs for the top lights.  A small piece of PC board was used to mount the usual limiting resistor and stuck to the cab roof with double sided tape.

Class 66 Class 66

Class 66 Class 66

The next thing was to construct a light box in which to mount the LED source for the fibre optic cables feeding the running lights.  I found a piece of rectangular Plastruct tube in which the LED fitted perfectly.  A piece of plastic mini strip was glued across one end and two small holes were drilled in the centre to align with the end of the LED lens. 

The fibre optic cable needed to be small diameter to enable it to bend easily in the tight space available and to pass through the small hole at the side of the chassis.  Unfortunately the running lights alignment was very near the edge of the chassis so only a small hole could be drilled through on an angle to avoid weakening the chassis corner.  As it turned out there was an advantage here in that the smaller optical fibre limited the light transmission giving a more realistic light level from the running lights.

Class 66
Here you see the light box in position with one of the fibre optics poking through the chassis at the top of the picture before it was cropped off flush with the chassis.  Red tower LEDs are mounted in the chassis holes and squeezed in between the fibre optic cable and the top red LED you can just see the white headlight LED.  The forward cab is very tight for room being adjacent to the motor mount so it does look a bit of a rats nest but as long as the joints are electrically sound and there is no danger of short circuits, who cares? - it is all covered over by the internal cab detail anyway.  I did have to remove a couple of small sections from the lower front edge of the cab detail to accommodate the red LED’s.
Class 66
In this picture you can see the decoder mounted in the roof of the body, the rear cab toplight and the central PC board I mounted on the chassis to take the limiting resistors, one each for all the remaining LED’s.  You can see that the wiring including the light box is a lot neater in the more spacious rear cab area. 

I didn’t bother with the DCC ready plug preferring to hard wire the track pick up and motor connections directly to the existing PCB. 
Class 66
Close up view of wiring.
Class 66
This is a full view of the finished wiring.
Class 66

So, how does it look on the track? 

F0 on - sidelights

Class 66

Daylight running headlight.

F1 switched to on.

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F1 switched off – F3 switched on
Class 66


F1/F3 both on (F2/F4 operate the same lights on the rear cab when loco is travelling in the opposite direction).

Full forward lighting.

Class 66
Rear lights.  The red LED’s always seem to colour saturate the camera – in reality there is no white centre to the light.

 

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