DCC conversion and LED Lighting update of the Hornby FGW Class 43 HST Pair.

(A supplement to the Cross Country Class 43 update)

 

 

Introduction:

A summary of the process adopted to incorporate DCC decoders and correctly operating external LED lighting in the First Great Western variant of the Hornby Class 43 diesel pair (OO gauge).

Note that the smaller pictures can be enlarged by clicking on the image.

 

Hornby Class 43 locomotive  High Speed Train with First Great Western Livery

 

The Hornby FGW Class 43 starting point:

The FGW units are DCC fitted, using Hornby decoders in each car. There are electrical pick-ups on all wheels of each car. Only one unit (the power car) is fitted with a motor. The centrally positioned power car motor is equipped with flywheels and applies drive through shafts and universal joints to each bogie assembly. A system of gears within the bogies transmits the drive to all 4 wheels in each bogie. The lights are directional and activate via button zero on the DCC controller. The leading car exhibits right headlight and two outer marker lights plus the cab light. The trailing car shows two outer red rear lights. The forward lights have a distinct blue shade. The intensity of the headlight is somewhat higher than the marker lights, but is not bright enough to be realistic. The rear lights look much more plausible. The motor control on the power car is not incredibly smooth.

 

Power Car Front lighting

Power Car Rear lighting

 

 

 

DCC Conversion Approach:

The FGW variant of the Hornby Class 43 differs in several respects from the Cross Country units already modified. Details are shown below. The plan is to use a 4 function plus "back emf" motor control decoder (ESU LokPilot V4) in the power car and a 4 function only decoder (TCS FL4) in the unpowered rear car, providing correct operation of headlights, marker lights and rear lights during day or night running plus manually controlled cab light illumination.

 

 

The  FGW lighting system as found in the non-powered car:

The FGW lighting boards use just two LEDs: Red for the rear lights and "white" for both the right hand headlight and marker lights. A similar arrangement of light pipes to those of the Cross Country variant is used to transmit the light to the front lenses, except that an extension to the rear of the combined rearlight / marker light pipe picks up peripheral light from the headlight LED during forwards motion and the shroud surrounding this light pipe is a simpler moulding using white plastic that does not enclose the light pipe as comprehensively as in the X Country unit.

The headlight LED is some distance from the same convoluted headlight light pipe, resulting in a dim headlight beam. The left (night running) headlight lens is fitted, but there is no illumination provided. 

Pointing a daylight white tower LED into the rear of the light pipes, outside of the loco body, shows that the transparent plastic has a slight blue tone and is very lossy......this seems the most likely reason for the dim bluish headlamp. Hopefully less critical for the marker lights, where the hint of blue conveys the LED nature of the real thing (although these are actually white!). Pointing the white tower LED into the rear of the the left hand headlight moulding (installed in the body front) was much more promising, with a bright substantially white output from the lens. Powering up the Hornby white LED, away from the light pipes outside of the loco, showed this to be substantially white in colour, providing further evidence to suggest that the blue tone is probably due to the light pipe material. One thing is for sure: to get the right hand headlight bright and white, the bendy light pipe moulded on the back of the lens has got to go!

 

Separating top & bottom

Inside the front bodyshell

 

Detailed cab interior

 

Lighting PCB & cover on rear of cab moulding

 

Optical paths left in the front body shell

 

Light pipe & shroud for rear & marker lights

 

Front view

 

Headlights in the front body shell

 

Right hand headlight ready for light pipe removal

 

Main PCB topside

Main PCB underside

 

 

 

 

The new lighting Requirement:

The left hand headlight is to be made operational, also whiter and brighter than the original right headlight.

The right hand headlight is to be made whiter and brighter while the rear lights may be slightly reduced in intensity.

The marker lights may be made whiter.

It will be possible to operate with the following lighting options:

1)     1) No lights

2)      2) Daylight right hand headlight plus both side marker lights at forward end / rear lights at rear end (activated by button 0).

3)      3) Night left hand headlight plus both side marker lights at forward end / rear lights at rear end (activated by button 1)

4)      5) The cab light will be activated by button 2 in the forward direction only.

 The lighting PCBs will be left unmodified. Switching transistors will be used to facilitate this if necessary.

 

Un-powered Car Circuit Diagram:

 

 

Lighting Improvements:

New bright Left hand headlight:

A pre-wired daylight white chip LED, is fitted in a rectangular hole made in the rear of the light pipe shroud, immediately behind the rear block of the left headlight lens.

New brighter Right hand headlight:

Using a similar approach to that described for the Cross Country unit. A plasticard mount is constructed to support the LED. This is glued to the light pipe shroud. The light pipe is removed from the back of the lens, so that the new LED can beam directly into the lens rear.

Modifications to the light pipe shroud & new LEDs

A drop of white paint around the edge of the LEDs

Modified Right headlight lens (minus original light pipe)

 

A few further modifications around the new LEDs

 

Both new headlights running at around 10mA

 

Light leaking through the plastic

Brought under control by gloss black paint

 

Original headlight LED blanking plate painted matt black

 

Blue colour cast on marker lights:

Hornby LED looks white.  Substituting a known daylight white LED still produces a blue cast. Repainting the internal blue body colour white or black makes no difference to blue cast.

Conclusion... its probably down to the light pipe material.  So we'll live with it.

 

Just two resistors and two diodes to add to the PCB, using the spare pads, after a few track cuts, then add the FL4 decoder

Finally reassemble the upper body shell to the chassis

Unpowered Car TCS FL4 Decoder CV Programming:

 

Description

CV number

Value

Green  (Right Day headlight reverse)

51

16   (or 28 for 50% brightness)

Purple (Left Night headlight reverse)

52

16   (or 28 for 50% brightness)

Brown (rear lights forwards)

53

0

Pink (cab light reverse)

54

16

Green via button  0

35

2

Purple via button  1

36

4

Brown via buttons  0&1

39

5

Pink via button  2

40

8

   

 

 

Trailer Car Under Test

 

(Reverse) Daylight running button 0

(Reverse) Night running button 1

 

(Forward) Rear Lights Button 0 or 1

 

(Reverse) Cab Light on button 2

 

(The headlights & marker lights can be made a little less bright via the TCS 50% dim facility if required)

With 50%  brightness

The headlight looks more realistic, but the marker lights are now too dim, so ......

It would appear that the resistors in series with the headlight LEDs need to be increased in value (e.g. to circa 2k7)

 

Location of the resistors concerned

 

 

 

 

Next, the Power Car

 

 

The Power Car with original decoder removed and the cab light LED wires disconnected

The three wires from the front lighting boards are labelled

GND, FR+ and FW+ so it appears that a negative ground lighting board is used on the power car! (Unlike the positive ground board used in the trailer car.)

 

 
Power Car Circuit Diagram:

Unfortunately Hornby have chosen to use a common negative connection for their lights PCB in the power car. I'm not sure why, as to illuminate the LEDs, Hornby have fitted quite a complicated circuit on the power car main PCB, which achieves nothing more than the much simpler circuit used in the un-powered trailer car main pcb assembly, but at significantly more cost. Either I'm missing something, or they really should get their electronics independently reviewed!

To avoid dismantling the lighting board assembly (with high risk of collateral damage) I will fit a pair of PNP switching transistors and some diodes to enable the decoder common positive function outputs to drive the pair of common negative lead LEDs. The redundant Hornby SMD parts will be removed from the main PCB, to provide a mounting area for the new transistors, diodes and resistors.

2k7 resistors are fitted in series with the headlights, to see if this gives a more realistic solution than the 1ks used in the un-powered car previously. (If it looks better, the unpowered car 1ks will also be replaced with 2k7).

 

 

 

The Power Car Modifications:

The replacement headlights are fitted using the technique already described above for the un-powered trailer car........

The original circuit components on the main PCB are removed. A double sided adhesive foam pad is fitted on the top of the main PCB. The circuit shown above is constructed on the foam pad.

The 8 pin DCC socket is used to connect motor and track pick-up connections to the decoder

 

Transistor circuitry

Routing of decoder wires

 

 

Power Car ESU LokPilot V4 Decoder CV Programming:

 

Description

Register CV31 Value Register CV32 value

CV number

Value

F(0)f    Button 0 forward  (green wire) day headlight 16 2 330 4
F(0)r   Button 0 reverse (yellow wire) rear lights 16 2 346 2(def)
F(1)f   Button 1 forward (purple wire) night headlight 16 2 362 8
F(1)r   Button 1 reverse (yellow wire) rear lights 16 2 378 2
F(2)f   Button 2 forward (white wire) cab light 16 2 394 1
F(2)r   Button 2 reverse no action 16 2 410 0

 

 

 

 

Power Car Under Test

 

(Forward) Daylight running button 0

(Forward) Night running button 1

 

(Reverse) Rear Lights Button 0 or 1

 

(Forward) Cab Light on button 2 (plus button zero)

 

 

Headlight Brightness:

The headlights are now fitted with 2k7 series resistors and this gives a reasonable light level (maybe still a little over bright, but a big improvement on the original Hornby light levels) ........ The un-powered trailer car has now also been modified, with 2k7 resistors replacing the 1k originals and the TCS FL4 decoder reprogrammed to set headlights and marker lights back to 100% brightness.

 

Headlight black edging trim:

The black painted edging around the front of the headlight lenses has imperfections. But beware!!!, while trying to overpaint these with satin finish black enamel paint, excess paint capillaried into the interference fit between the lens and its hole in the body shell. This had a spectacular effect on the level of light transmitted through the lens! A swift dismantling exercise was immediately initiated to enable the lens to be withdrawn and cleaned before the paint dried.  So... if trying to remedy imperfections in the headlight edging.... only use viscous paint and be very careful where it is being applied! 

Other Issues (and fixes) found in similar Hornby Class 43 power and trailer cars:

1) Missing original lights.

Dismantle upper & lower body halves, slide the front spring contacts over their pads a few times and re-assemble. If still a problem, apply 5 volts DC through a 1k series resistor directly across the spring contacts in the upper body shell to test the LEDs. If a dead LED is found:

As carefully as possible, separate the problem lighting PCB from its front cover screen. This probably requires the assembly to be separated from the front of the cab moulding. Some damage to the fixing lugs is probable. Remove and replace the problem LED, make sure the new LED is working OK then re-assemble, using superglue to repair any lug damage.

It may be necessary to hardwire the connections between upper and lower body halves, to replace the spring contacts, if the PCB assembly is no longer rigidly attached to the front of the cab moulding.

2) Metallic scraping noise from power car flywheel (contacting on the metal chassis block).

If improved by loosening the motor screws, fix by removing the motor and substituting home brew spacers a little thicker than the Hornby originals, between the motor fixing brackets and the chassis block around the motor fixing screws. 

 

 

Supplier website links:

 

Digitrains    Good source of specialised DCC items including nano lights
Bromsgrove Models    Excellent source of DCC decoders and specialist LED devices for this type of project
Rapid Electronics    Good online supplier of general electronics components at good prices
South West Digital    Primary source for ESU LokPilot decoders
TCS (Train Control Systems)    A U.S. company. My preferred DCC decoder family with good programming data and advice on their website.
Maplin    A convenient local source of basic electronics components including resistors and transistors

 

The photos of the model FGW class 43s were taken on the kitchen worktop using a hand held Canon Ixus 220HS    

 

 

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