DCC conversion and LED Lighting update of the Bachmann Class 221 Voyager 5 car DMU.

 

Introduction:

This page provides a summary of the process adopted to incorporate DCC decoders and correctly operating external LED lighting in the Cross Country Trains variant of the Bachmann 5-car Class 221 Voyager (OO gauge).

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

 

Cross Country Voyager

DCC Conversion Approach:

The plan is to use a decoder utilizing back emf motor control in the centre power car (TCS type T1) and a function only decoder with 4 outputs in both the leading and trailing cars, providing correct operation of headlights, marker lights and rear lights during day or night running (TCS type FL4).

External Lighting Modifications:

The Bachmann model includes bulb lighting which illuminates the external light lenses via plastic light pipes. The original lights provide correct daylight operation, but offer no night running option. The bulbs draw enough current to run hot, and have a finite lifetime. They will therefore be replaced by LEDs.

Both lower light-pipe assemblies will be removed, and the headlights, lower marker lights and rear lights, will be changed to individual LEDs. The top marker light-pipes will be retained, illuminated by new LED devices.  The DCC decoder programming will be arranged to handle correct day and night running of the lights via function buttons 0 and 1 respectively. (For day running, right hand headlight, left hand and top marker lights in the forward car plus both rear lights in the rear car. For night running, left hand headlight, right hand and top marker lights in the forward car plus both rear lights in the rear car.

 

 

Circuit Diagram for end car lighting and power car motor connections:

In the power car, only the motor (orange and grey wires) and track (red and black wires) are connected. In the end cars, only the track and lighting connections are used (red/black, green, purple, brown, pink and blue wires). The resistors control the current flowing through each LED. This determines the intensity of the light generated by the LED. The values were established by experiment. Some adjustment may be required if different LED types are used or if light level refinements are thought necessary.

 

Achieving Access to the end cars:

First the upper body shell must be separated from the wheeled chassis unit.  If the car is correctly assembled by the factory: The two screws in the chassis unit immediately inboard of the bogies must first be removed. Next remove the securing screw for the deflector in front of the forward bogie. Remove the deflector assembly. The lower edges of the sides are gently eased outwards to release the 4 plastic clips near the centre of the car, allowing the two assemblies to be separated.  (Slipping pieces of thin cardboard between the clips and the inner upper-body sides can assist this process). The electrical connector in the wiring between the two assemblies can then be separated. 

If however, like my samples, stray adhesive has bonded the deflector side pieces to the front body skirt or the upper body shell ..... and on the trailer car, further stray glue had bonded the front of the chassis to the upper body shell ....... then a somewhat more aggressive approach is needed: Being careful not to damage the outside paintwork, I had to gently separate the front body skirts from the main upper body shell by using a suitable small flat screwdriver as a lever. Then on the trailer car, I used the same technique to prise apart the front of the chassis and the upper body shell. Fortunately, the pieces came away cleanly at the bonding surfaces, so I was able to later reassemble (and this time, correctly, glue) the parts together again, after cleaning up the bonding surfaces with a needle file, but without the need to touch-up the paint work.

The removal of the front side skirts did have the positive advantage of giving better access to the lower front light housings.

Front screws

Rear Screw

Leading car, which finally separated with the front skirts attached to the chassis rather than the upper body shell !

 

Access to the Lighting PCB Assembly:

The Bulb housing assembly includes a PCB fixed to the roof of the upper body shell. To remove the assembly, first undo the tiny posidrive PCB fixing screw. Then withdraw the light housing assembly rearwards to separate it from the light pipes. When clear of the light pipes, the assembly can be removed from the upper body by easing the sides of the car apart.

 

Location of bulb housing assembly fixing screw

 

Slide the bulb housing assembly to the rear

 

Bulb housing removed showing the light pipes

Lower light pipes removed

 

Removing the lower lightpipes, left headlight blank and right marker light blank:

The lower light pipes were not glued and could be removed simply by withdrawing towards the rear of the car.

If you are lucky, the remaining lighting lens blanks are not well glued in place and can be extracted with a careful pull on the rear or push on the front. Otherwise, it's a case of drilling through the transparent blank to enable a replacement LED to be accommodated. The lens tunnels need to be shortened at the rear of the light housing, with a craft knife, so that the outer surface of the tower LEDs sit just below the outer surface of the light housing.

 

The replacement LED fit:

All LEDs are first over painted with opaque gloss black paint (except for light exit faces) to prevent unwanted light escaping. The cathodes (negative end) are marked using a white dot, so that polarity is clear after the leads are trimmed.

Headlights and lower marker lights use 2mm pure white tower LEDs.

A clear glazing filler will be used to produce a flush outer surface for the above LEDs.

Rear lights: Miniature 1.6mm red LEDs plus lens made from the original light pipes.

Top marker light: 2mm pure white tower LED beaming into original light pipe.

 

Painted LEDs

 

Fitting the new LEDs:

1) The Top Marker Light.

The PCB is separated from the original bulb housing. The top marker light bulb housing is carefully dismantled to enable the bulb to be removed. The diodes and wire connections are all removed from the PCB, using a soldering iron. A 2mm tower LED will just fit inside the top marker bulb housing (with the original metal base plate omitted). Holes are drilled through the PCB for the new LED leads and the LED plus top bulb housing are re-assembled. The PCB is then refitted to the upper body shell, with the original light pipe inserted into the front of the metal bulb housing.

Top Marker PCB in place

 

2) The Rear Light Lenses

The lens cylinders are cut from the original rear light pipe using a sharp craft knife. These are then glued into the upper holes in each light assembly, leaving a small hole on the inside for location of the 1.6mm red LEDs.

Rear Light Lenses in place

 

3) The Rear Lights

The rear light LED leads are bent to provide sections that lay flat on the inner body shell surface. With the hemispherical end of the LED inserted in the rear light tunnel behind the lens, the leads are glued to the upper body sidewall with superglue.

Rear Light LED in place

 

4) Headlights and lower marker lights

Before these are fitted, the internal "shelf" under the windscreen (which fell out) is refitted using super-glue. The 4 tower LEDs, are then inserted into the remaining light tunnels in the two front light housings. The leads are formed to combine the common positive LED connections down the sides of the cab and the series resistor connections towards the cab centre line. The series resistors are then soldered to the LEDs and combined as shown in the circuit diagram, ready to be soldered to the decoder wires. Care is taken to keep all the bare wires isolated from each other.

LEDs and series resistors in place

 

Connecting the FL4 decoder:

Trim and connect the decoder wires as shown in the circuit diagram, with the decoder mounted on a double sided foam tape pad immediately behind the PCB in the roof of the car.  Route the decoder wires so that they are not obvious when viewed through the windows.

Remove the flying lead connector assembly from the small PCB on the chassis unit and solder the red and black decoder wires to the PCB instead. Use the PCB track pads which already terminate the chassis wheel contact red and black wires.

Then place the chassis unit on a test track to programme the decoder and test the lighting operation under DCC function button control. (See the table below for the programming CV values, in  the Leading car FL4 column.)

 

Decoder, LEDs and series resistors in place

Programming the CVs:

 

CV purpose

CV Number

Leading car FL4

Power Car T1

Trailing Car FL4

Lighting control

Green wire (forward end 1, reverse end 2)day HL-dim

51

8

-

24

Purple wire (forward end 1, reverse end 2)Night HL-dim

52

8

-

24

Brown wire  (forward end 2) rear lights no-dim

53

16

-

0

Pink wire  (forward end 1, reverse end 2) top light no-dim

54

0

-

16

Button Mapping

Green wire map to button 0 for day running

35

1

-

2

Purple wire map to button 1 for night running

36

4

-

4

Brown wire map to buttons 0 and 1

39

6

-

5

Pink wire map to buttons 0 and 1

40

5

-

6

Dimming Control

Headlights dim when stopped (16)+BEMF on (1)

61

16

1

16

Dimmed intensity

64

6

-

6

Dim headlights always:  enable via button 3

123

16

-

16

Motor Control

 

 

 

 

Acceleration delay

3

-

12

-

Deceleration delay

4

-

12

-

The "rule 17" dimming option provided in the TCS decoders has been used, so that when the train is stationary, the headlights and lower marker lights are dimmed. As soon as the train is made to move, these lights come up to their normal intensity.

 

Testing the Lights:

Button 0 should activate the day running lights (right hand headlight with left hand marker light in the forward direction for this car and both rear lights in reverse).

Button 1 should activate the night running lights (left hand headlight with right hand marker light in the forward direction for this car and both rear lights in reverse).

 

Day running lights are OK (button 0)

Night running lights are OK (button 1)

Rear lights work OK (rev, buttons 0 or 1)

 

Completing the end car assembly:

Now that correct operation is confirmed, re-fit the upper body shell to the chassis unit (using the clips and screws). NB: If the new headlight LEDs protrude downwards too far, it may be necessary to remove a little plastic from the front ledge of the chassis to enable a good fit. Make good any bonds that failed during the disassembly process.  This completes the first end car modifications.

 

Modifying the second end car:

The other end-car updates are similar except for minor differences in the CV programming, due to the reversed direction of travel of this car. [Also, on my example, due to additional stray glue from Bachmann, holding the front chassis to the upper body shell.] The CV details are shown in the Trailing Car FL4 column of the CV table above.

--------------

Modification of the power car:

The modifications to the power car concern the motor wiring, which must be changed for DCC operation.

Separate the upper body shell from the chassis, first removing the 4 screws and then easing the upper body sides apart, to release the 4 body side clips.

Make a note of the orientation of the upper body shell with respect to the chassis, as it only fixes correctly one way round (due to asymmetric side clips).

 

Power car fixing screw locations

Chassis separated from upper body shell

Mounting the power car decoder:

The power car T1 decoder is mounted above the motor in the power car. First the PCB above the motor is unscrewed and the two coils plus capacitor are de-soldered and removed from the PCB (these RF suppression components are not required for DCC operation). The T1 decoder is then located on top of the plastic motor housing and the PCB is refitted, clamping the decoder in place. The red, black, orange and grey decoder wires are then soldered to the appropriate points on the top of the PCB. (As shown in the circuit diagram.)

 

PCB unscrewed to give access to the coils and capacitor

The T1 decoder is then sandwiched under the PCB

 

Showing the 4 decoder wires soldered in place on the PCB

(Note: I had to reverse the orange and grey wire connections later, to achieve the correct direction of movement)

 

Completing the power car assembly:

Program the T1 decoder using the CV values shown in the Power Car T1 column of the CV table above. If the direction of motion is incorrect, either turn the power car through 180 degrees within the consist or reverse the grey and orange wire connections on the PCB. [NB: I had to reverse the connections on my unit to set up the train as indicated in the consist diagram accompanying the product] CVs 3 and 4 control the acceleration and deceleration characteristics and can be adjusted to different values if preferred. (Consult the T1 data sheet for further details of additional CV functionality).

With correct operation confirmed, the upper body shell can be clipped and then screwed to the chassis unit. This completes the power car modifications.

When the desired train address has been chosen, programme the same address individually into each car fitted with a decoder, sequentially, on the test track. Then place all 5 cars on the main track, couple up and verify that operation is as expected.

 

The completed 5 car Voyager Train

Supplier website links:

 

Hattons of Liverpool    The Class 221 Voyager unit above was purchased from this very reliable mail order company.
Trains 4 U (Peterborough)    A good (almost local) source of Bachmann and Dapol product. They also stock TCS decoders and offer good technical advice.
Bromsgrove Models    Excellent source of DCC decoders and specialist LED devices for this type of project
DCC Supplies    DCC specialist supplier based in Worcestershire. Good prices on Tower LEDs and TCS decoders
TCS (Train Control Systems)    A U.S. company. My preferred DCC decoder family with good programming data and advice on their website.
Maplins    A good local source of basic electronics components including resistors and transistors

 

The photos of real class 221s were taken at York during 2009.  The photos of the model were taken on the kitchen worktop at 200 ISO using a tripod.    

 

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