DCC Conversion, Sound And Lighting Update Of The Bachmann Class 150/2  Two Car DMU, sourced resprayed in Northern Rail colours from Olivia's Trains.



Class 150/2 at York July 2009

150201, the subject of the model !



This webpage is a follow-on to the first DCC and lighting update carried out on a Bachmann Class 150/2 in Regional Railways colours. Original plans to repaint this unit in Northern Rail colours were abandoned when it became clear that removing the silver lined window modules would not be possible without considerable risk of collateral damage.

When I came across the Northern re-spray at Olivia's Trains, I decided to go for an early birthday present and achieve my Northern model via that route instead.

This conversion will be a little more ambitious than the first, using a sound equipped decoder and adding working side mounted "hazard lights", to be synchronised with door operation. The night headlight and cab/destination lights will also be fitted. However, due to the all pervading motor casting which fills the power car passenger space, no passenger compartment lighting will be attempted. (Unless I get a really good idea).

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


Real Northern 150 front end

Full left hand side view of real 150

Full right hand side view of real 150


                Olivia's interpretation:

Northern Rail Class 150/2 as received from Olivia's Trains

Would benefit from some tidying up in the corners of the doors, the underside of some windows and the door buttons & labelling

Cosmetic tweaks:

The Northern Rail colour scheme is complicated but is reproduced quite well, however there are a few issues, as can be seen in the real Northern 150 photos above and below:

The black surround to the front windows on each car extends almost the full width of the car and extends right up to the roof line, which should have a curved orange cant rail across its lower edge. The blue surround to the lower sides of the drivers doors are missing. The external door buttons should be square and have rectangular labels above them.

The silver trim around the lower edges of some windows requires some tidying up. The corners of the door frames and the yellow steps also require some attention, where the white undercoat shows through.  The upper body paint finish is not very even with a lot of speckle in some areas. It would probably benefit from a matt overspray, perhaps with some light weathering to suppress reflections. I'll address these issues later in the project.


DCC Conversion Approach:

The plan is to use a 4 function and back emf motor controller sound equipped ESU LokSound V4 decoder in the power car and a 4 function TCS FL4 (function only) decoder in the trailer car. To provide correct operation of day and night external running lights, 4 function outputs are required. The two inter-car conductors in the coupling bar will be used to link the driving car wheel connections to the trailer car decoder.

External Lighting Modifications:

The Bachmann model correctly reproduces real world daylight operation, with a right hand headlight, both marker lights and both rear lights fully operational.  A left headlight for night running will be added. Also to be added are the door open "Hazard lights" half way down the side of each car and destination plate illuminators which will double as cab lights.  During day running, the right hand headlight and both marker lights are used in the forward car. During night running, the left headlamp and both marker lights in the forward car are used.

It is planned to add the missing lights, modify the lighting hardware circuit and arrange for the DCC decoder programming to handle correct day and night running of the lights via function buttons 0 and 11 respectively. Hazard lights will be mapped to the door opening sound command button and the destination/cab light will operate in parallel with the day & night forward lights.


Day running Lights

Night running lights


Circuit Diagram for trailer car lighting connections:


The series resistors control the current flowing through each LED. This determines the intensity of the light generated by the LED. The values were chosen subjectively based on memory of the real DMUs. Some adjustment may be required if different LED types are used, or if you prefer a different lighting intensity.


Adding the night running headlight:

The same approach is used as described in the previous Class 150 webpage, except that pre-wired daylight white Nano-light chip LEDs are used for the new headlights. (The rear light LEDs are again reversed on the PCB and their negative end pads are isolated to enable independent series resistors to be used).


The Hazard Warning lights:

The amber hazard warning lights are situated half way down the sides of each car, as shown in the photograph below.  (Click the image to enlarge).

Class 150 at York

In normal operation, these lights switch on while the train has the doors open at the station platform, then switch off when the doors close, before the train pulls away. I understand that the lights provide an external indication if certain critical systems fail in the car concerned, including the braking system.

On the model, the non-operational hazard light units are drilled through the centre and the aperture is opened up using needle files, until an amber chip nano-light can be fitted and glued into the hole. Glue and Glaze is used to form the light cover, which is painted orange using water colour paint.

Before painting

The LEDs common series resistor is glued within the upper body shell and the enamelled LED leads are terminated in 0.5mm flex for connection to the chassis PCB (at the cab end of the car) before the upper and lower body sections are re-assembled.

Adding the cab/destination light:

The same approach is used as described in the previous Class 150 webpage, using a warm white tower LED. The positive connection is shared with the hazard lights.

Cab/destination board LED & Hazard lights wiring glued to roof underside


Wiring up the trailer car:

The same approach is used as described in the previous Class 150 webpage, but this time the additional lights in the upper body shell are also connected before re-assembly of the car. In fact the FL4 decoder was programmed and the lighting functionally tested, before the components were fixed to the adhesive pad, to enable any resistor value adjustments to be made more easily. The upper body shell connections were then de-soldered to allow the chassis to be completed as shown below.


Chassis mounted parts ready for re-assembly

(After programming and testing)


Additional resistors & diodes on adhesive foam pad.

Decoder wires taped down


To simplify any future software changes

A pair of track contact wires is made available

Seating replaced before the wires connecting

to the upper body are trimmed, soldered and sleeved


Finally, the wires connecting to the upper body were trimmed as short as practical, soldered to the corresponding, trimmed upper body wire and the joints protected with heat shrink sleeving. With some difficulty, the upper and lower body assemblies were then re-assembled. The dummy BSI coupler and deflector / snow ploughs were then fitted to the trailer car.


Programming the Trailer Car FL4 CVs:

Using the DCC controller (mine is a Bachmann Dynamis) the trailer car FL4 CV values are programmed into the decoder.

CV purpose

CV Number

Trailer Car FL4

Lighting control

Green wire (reverse end 2)day no-dim



Purple wire (reverse end 2)Night no-dim



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



Pink wire (forward or reverse) hazard lights no-dim



Button Mapping

Green wire map to button 0 for day running



Purple wire map to button 11 for night running



Purple wire map to button 11 for night running 38 64

Brown wire map to buttons 0 and 11



Brown wire map to buttons 0 and 11



Pink wire map to button 4




The lighting works correctly as planned, but testing will be repeated in combination with the power car later


Completed Trailer Car




The power car lighting PCB is modified in a similar way to that of the trailer car. The Hazard lights and cab/destination lights are also fitted in the same way. However, in addition, the main PCB assembly and circuitry is heavily modified, the decoder is fitted and the sound system speaker is put in place.  

The power car upper body shell and chassis assemblies are separated using the same techniques as already applied to the trailer car.


Modification of the power car:

In order to fit the speaker and route its wires to the main PCB, the chassis assembly is further dismantled.


Dismantling the power car chassis:

The power car chassis is built around the substantial motor casting. The 4 wires fixed to the main PCB are disconnected and the 2 fixing screws are extracted, enabling the PCB to be removed. The bogies are removed by undoing the single fixing screw to the motor casting and withdrawing the drive shafts from the universal joints in the centre of the motor flywheels. The plastic sub-chassis can then be separated from the motor casting by releasing the 6 side clips. The front lighting PCB is unscrewed from the plastic back plate. On my example, the LED light sheild moulding also fell away from the plastic sub-chassis. (This will need to be glued back in position when the locomotive is re-assembled).



Circuit Diagram for the power car:


Fitting the speaker:

The sound system loudspeaker is fitted to the under frame of the power car. Howes recommend a 4 ohm elliptical speaker type 50334 which fits within an enclosure measuring about 22mmx42mmx12mm. A bit of surgery is required to accommodate the speaker, out of sight, behind the battery boxes and fuel tank side mouldings. The rear of the enclosure fits through a hole cut in the underframe floor.


planned speaker location


The fuel tank moulding and individual cylindrical tanks are removed and a hole is cut in the underside of the plastic sub-chassis to accommodate the rear of the speaker enclosure. The location is determined by some protrusions in the metal chassis block, which resulted in the speaker sitting closer to the front bogie aperture than originally anticipated. The speaker is glued into position using cyanoacrylate adhesive (super-glue). The fuel tank assembly is then cut to fit around the speaker. Some of the cylinder parts were glued in place in an attempt to hide the end of the speaker enclosure near the bogie, but these had to be removed as they obstructed the bogie. The speaker wires are routed through the chassis block, emerging directly under the main PCB. (The wires are bonded to the inside walls of the chassis block so that they do not interfere with the nearby drive shafts.


Actual speaker location


End view showing the speaker enclosure

  penetrating the floor


The Lighting modifications:

The same changes are made to the power car lighting PCB assembly as those made to the corresponding trailer car assembly. (In line with the circuit diagram above). (The rear light LEDs are again reversed on the PCB and their negative end pads are isolated to enable independent series resistors to be used). A new daylight white pre-wired chip LED is glued to the front of the lighting PCB, between the left hand marker and rear light LEDs, using superglue as a combined insulator and adhesive.


Modified Lighting PCB

Rear of Lighting PCB

The PCB assembly and the shield moulding (which prevents cross coupling of light between adjacent LEDs) are re-fitted to the front of the chassis. The extra wires now fitted to the rear of the lighting PCB are routed through holes drilled in the plastic panel behind the PCB. 


Hazard lights and destination illuminator / cab light are also added in a similar way to those in the trailer car, except that a pre-wired chip LED is beamed through the hole in the cab rear bulkhead in place of the tower LED as there is much less available space in the power car at this location.


The main PCB:

All of the SMD components, except the decoder connector, are removed from the board as the new circuit is quite different from Bachmann's original concept. Additional connections for the function outputs Aux1 & Aux2 are made to the 21 pin decoder connector, using very thin enamel coated copper wire. The two tracks leading to the rear coupler are isolated and then connected to the left and right, rear wheel contact pads.

 Top and bottom of the main PCB before modifications (The 21 pin blanking plug has been removed)


Detailed Modifications to the main PCB:

The 21 pin blanking plug is removed, leaving the wheel contact PCB copper tracks, the motor connections and the speaker terminals, available to the 21 pin decoder. The 2 tracks feeding the coupling bar wires are cut to disconnect the coupler from any remaining circuitry. The isolated coupler tracks are then re-connected to the wheel contact tracks by short, soldered wire links.

All the original surface mounted resistors, transistors, capacitors and diodes are removed from the main PCB and the terminations of the spring finger lighting board contacts are identified. 

New leaded resistors (and the pair of diodes) are fitted, mounted on an adhesive foam pad fixed to the main PCB.    

The decoder function output tracks are identified and traced. New wire connections are made to the 21 pin connector for the Aux1, Aux2 outputs. 



The bogies are refitted, the PCB is screwed into position and the lighting PCB connections are wired to the main PCB. (Wire connections are considered more reliable than the original spring finger system).  The corresponding metal strips in the upper body shell are removed.


LokSound V4 Decoder Programmed Button mapping:

Many thanks to Bryan from Howes for programming the LokSound V4 to provide the operation described in the table below. This slightly non-standard arrangement brings the sound (and lighting) operation almost in line with that of my Northern Rail sound equipped Class 158.




Operating Function

Function output

F0 (Forward only)




F0 (Reverse only)



Rear light (yellow function wire)


Sound on/off




Horn 1 two tone




Horn 2 two tone




Doors open


Front light (white function wire)


Guard’s whistle




Doors close




Driver/guard buzzer




Flange squeal





Shunt mode




Acceleration/Deceleration override


F11 (Make "Forward only")




F11 (Reverse only)



Rear light (yellow function wire)






Single Horn



F26 Re-assign to F11 reverse only




Re-assembly continued:

The 21 pin decoder plugs directly into the Bachmann decoder location:

Pre-programmed LokSound V4 Decoder from Howes Model Shop

The lighting wires from the upper body shell (hazard lights and cab / destination board light) are arranged to lay over the top of the main PCB when the upper body shell is re-united with the chassis assembly. The upper body is supported on a book adjacent to the chassis while the wires are soldered to pads configured on the main PCB.

(The blue common positive wire shown above was a shade too short, so had to be replaced with a slightly longer wire to allow the body halves to come together)



First results with the assembled cars coupled together:

After fitting the longer blue wire, it was possible to clip and then screw the two power car body halves back together again. The Obstacle deflector and BSI coupler were glued in place and the conductive coupler was inserted into the rear socket. The trailer car was also attached to the conductive coupler and for the first time, the two cars could be tried together. 


Daylight running lights and destination board

lighting is all OK. (It seems we're off to York!)

The hazard lights work too!

(Via button 4 which also makes the "doors open" sound)


The sound system works extremely well.... nice one Bryan!


Testing the Lights:

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

Button 11 should activate the night running lights (left hand headlight with both marker lights & cab light in the forward direction for the train and both rear lights in the reverse direction for the train).

Button 4 should activate the hazard lights


Front view, Day running lights, power car  forward (button 0 and forward)


 Rear view, Day or Night running lights, power car forward (button 0 or 11 and forward)

Front view, Night running lights, power car  forward (button 11 and forward)


Front view, Day running lights, power car at back (button 0 and reverse)


 Rear view, Day or Night running lights, power car at back (button 0 or 11 and reverse)

Front view, Night running lights, power car  at back (button 11 and reverse)


Hazard lights (left) on (button 4)

Hazard lights (right) on (button 4)



Cosmetics: Some refinements required to the the original Olivia's paint scheme.....

As mentioned at the beginning of this project page, although the Northern Rail livery is fairly accurate, there are errors around the cab front, the front door frames and in the door opening buttons with missing labels. Also, the satin paint surface finish rather lets the overall effect down.  Fortunately I found it was possible to gently scrape away the worst of the over-spray of blue and purple on the silver window surrounds. However, the reflections from the roof and side walls need toning down. The next step is to clean up the door areas by over-painting the exposed white undercoat in the corners (with a very small brush). Additional blue paint is also added to the lower sides of the single end doors, to improve the paint scheme accuracy (Revel 51 is close enough). The steps and bottom of the doors are also tidied up where yellow was either missing or had overlapped on to the bottom of the doors.


The real 150201 in July 2009

After an initial tidy-up of the paint finish


The front of each car needs additional black painting around the windows and an orange cant rail that curves around the bottom of the roof line. Not looking forward to trying to curve a straight cant rail transfer around that curve.  I'd try painting the orange line but unfortunately there is no way my painting skills are up to that task! 

Although the 2009 photo of 150201 (above) shows yellow light housings, The model parts are left black as the 150 fleet now seems to have more black examples than yellow....... In fact I've just come across a later photo of 150201, on the web, showing one yellow and one black light housing! Hope the photographer will forgive its inclusion (on the right) as a much cropped and reduced size version of the original with no enlargement included, as I couldn't figure out how to contact him/her.


Black & grey paint in place

Cant rail (Fox) transfers in place


Next issues are the (missing) conspicuous labels above the door opening buttons.  I have a part used custom sheet from Precision Decals, which includes the no smoking, wheelchair and yellow warning labels that fit next to the doors on the real Northern 150s. Only problem...... just enough for one side of the DMU pair.  I'm in communication with Precision Decals in the hope of obtaining more.

Door button labels added to power car

I think we're gradually making progress in the right direction


The speckle finish on the car sides seems to be largely due to the final clear varnish coat. I've had some success gently abrading this with wadding carrier metal polish. The finish left after this process is a toned down gloss. It takes a lot of rubbing and I'm very wary around the original transfers, for fear of damaging them, but so far so good. Pending the acquisition of some new decals, I'll move on to the roof finish:

I've done a bit of Google & Flicker searching for Northern Rail 150/2 photos. The majority of roof colours are a significantly paler shade of grey than that of the Olivia's model. The surface finish is a combination of matt (in the weathered areas) and semi-gloss on clean curves of a recently painted roof, but scale effects mean a matt finish is probably best for the model, perhaps with some light dry polishing. The shade of grey that looks a good average (to me) is Humbrol 140 "Gull Grey". 


Roof painted "Gull Grey"

Orange cant rail transfers in place

Pastels added

The roof edges are first carefully hand painted with a thin band of paint that just covers the upper side of the orange cant rail. When this has dried, an area coat can be brushed on to the remainder of the roof, using a larger brush, lining out along the roof ridges. Two coats of paint may be needed. The roof side edges and front are lightly polished with metal polish to give a hint of a semi-gloss finish in these areas. Replacement orange cant rail decals are fitted over the original strips. Compared to photos, the roof looks too pristine, so the exhaust and central areas of the roof are treated with black pastels, rubbed in with cotton buds to darken these regions. (Very dark next to the exhaust, with more gentle treatment elsewhere.)

The new decals have arrived....Thanks John!...... 


Back to the sound chip

Having now heard all the sound sequences, the reverse double tone horn doesn't look as useful as the single tone, so I will change the button mapping so that button 3 now generates the single tone (in sound slot 4) and the reverse double tone horn (in sound slot 10) will be transferred to button 13. (This also makes the horn tones similar to my sound equipped 158.)

Button Action CV32 value CV New Value
3 Sound slot 4 to be actioned by button 3 2 398 8
3 Sound slot 10 no longer activated by button 3 2 299 0
13 Sound slot 10 to be actioned by button 13 3 303 2
13 Sound slot 4 no longer activated by button 13 3 302 0



.......Beginning to adjust the relative sound levels:

In addition to the master volume control (CV63), each sound slot can be independently adjusted in level.  The Howes defaults for all the sound slot levels, except the master volume, are at maximum. However, experience from my first sortie into sound on the 158, suggests that winding the main engine sound down a little, to slightly increase the relative level of the supporting sounds might be beneficial.

The 150 cvs are as tabulated below:


Before these adjustments, register CV31 is set to 16 and register CV32 is set to 1

Operating Button Sound Description Sound Slot Vol CV Original Value New Value
- Master Volume control - 63 Not known 32
1 Main engine sounds 1 259 128 (max) 100
2 Two tone horn (once) 3 275 128 (max)  
3 Single tone horn (once) 4 283 128 (max)  
4 Doors opening clunk (once) (plus hazard lights continuous) 5 291 128 (max)  
5 Guards whistle (once) 6 299 128 (max)  
6 Doors close warning tones, then clunk (once) 7 307 128 (max)  
7 Driver to guard acknowledgement buzzer (once) 8 315 128 (max)  
8 Flange squeal (continuous) 9 323 128 (max)  
13 Reverse two tone horn (once) 10 331 128 (max)  


That sounds about right!


The 150201 Pair, now complete, including both port and starboard decals.......


Subsequent Mods:

The trailer car now has wheel contacts added to the cab end bogie. These are connected in parallel with the original feed via the conductive coupler. This gives additional reliability to the train in case of dirty track sections and provides a load at the rear of the train that can be detected by the computer control.

YouTube Video of the finished train on the test track:

Click here for the video



Supplier website links:


Olivia's Trains    The resprayed Class 150/2 unit above was purchased from Olivia's Trains of Sheffield.
Howes    The sound equipped LokSound V4 decoder was ordered from this very helpful company.
Precision Labels & Decals    Extremely helpful company who produced customised Northern Rail decals for Class 142 and Class 150 units.....Many thanks John!
Digitrains    Excellent source for DCC items and lighting LEDs
Bromsgrove Models    Excellent source of specialist LED devices and TCS decoders for this type of project. 
DCC Supplies    DCC specialist supplier based in Worcestershire. Another helpful source of DCC and lighting components
TCS (Train Control Systems)    A well (web) documented basic DCC decoder family is available from this U.S. company.
ESU    My preferred sound and motor control decoder source. 
Maplin    A convenient local source for electronic components such as resistors and transistors


The photos of real class 150 units were taken at York railway station in 2009. The photos of the model were taken on the kitchen worktop using a Canon Ixus 220HS.    


Click to move to Model Rail Index Page