Adding DCC with improved lighting and a sound system to Bachmann's Northern Rail Mark 2 Class 150/2 (December 2014)



The new Bachmann Class 150/2 in Northern Rail livery, is an impressive piece of kit!  However, a few minor errors need fixing and I'm somewhat less impressed with the power car speaker arrangements!

Class 150/2 at York a few years ago.


What Modifications are involved?:

1. Bachmann have chosen 150204 as the subject of their new release..... which is a shade unfortunate as 150204 has the new twin lens lighting modules, which include combined LED rear and marker lights, while the model has the original style triple lamp assemblies (see below for detail).  LED changes are required, which will include new night headlights, replacement white markers, amber door hazard lights and a driver's cab light.  (I did briefly consider changing the number, but my soldering is generally more reliable than my painting!)

2. The new model includes some internal driver's cab detail including seats...... but the cab included is the full width type used on the 150/1. The 150/2 has a connecting corridor between two much smaller cabs. Plasticard mods and some Stanley Knife surgery required here!

3. Provision is made for a 40x20mm speaker, but this looks at first sight to be an acoustic disaster, with lots of scope for front-back cancellation. I think a better arrangement can be achieved in the trailer car, using an ESU enclosure and a miniature twin wire interconnect. A Howes LokSound V4 including Bryan's Northern Rail station announcements will be used, with a LokPilot FX V4 function decoder in the trailer car.

4. Internal lighting is provided by Bachmann, but this needs to be tested and may need some improvement. Although the revised motor housing is much smaller than the original, it still occupies a significant part of the power car and some camouflage maybe desirable. All wheel contacts in both cars will be interconnected (via the conductive coupler) to reduce brown out risk, although, there is  room for stay-alive or anti-flicker 1000uF 25V capacitors, under the power car floor and glued to the roof centreline at the rear of the trailer car.

More detail of the approach to be used is provided below:


1. The Running Lights:


The new Bachmann unit has the earlier style lighting modules


The real 150204 has the later style running lights

A better view of the later style running lights on 150273

Old style lights like Bachmann's (but with yellow fronts) on 150223

The small rectangular end lenses in the upper body shell will be filled and painted over.  The original yellow marker lights will be removed from the lighting PCB and new pure white LEDs will be added adjacent to the rear lights. The lighting shroud will be modified to allow either white or red LEDs to illuminate the inner lenses. A new white LED will be fitted behind the night headlight Lens (left hand side).   



The original Power Car PCB assembly.


Close-up of the original lighting board at the front end of the main PCB.


LED modifications: The original yellow markers are removed, while new white markers and a night headlight are added.

Pre-wired LEDs (by DCC Concepts from Digitrains) were super glued to the PCB. The night headlight also had an insulating pad underneath, to better protect an existing PCB track. The new marker wires were soldered to the original marker solder pads. The new night headlight positive wire was also bonded to the adjacent positive marker pad, while its negative wire was routed through a new hole drilled in the centre of the lighting PCB.

Next to find a way to accommodate some new resistors and diodes under the floor..................


The Developing Circuit Diagram


As I'm not using the power car speaker space, an easy location solution is available.




Although superficially this looked fine, taking a more critical look, the offset white marker LEDs resulted in a brighter marker light closer to the observer, when viewing the front of the car from an angle, rather than from directly in front. However, plan B overcomes this problem, by gluing a piece of white tissue paper between the LEDs and the rearlight / marker light lenses.  (See below.)


Showing single thickness pieces of white tissue paper, glued in place 1 to 2mm in front of the LEDs.




2. The cab modifications:

The 150/2 variant has the ability to re-configure the cab when operating in multiple, to close off the left hand driver's area, to prevent passenger access, while opening up a central corridor to allow passengers to cross to the adjacent car via the central communicating doors.

When acting as the lead car, the rear cab door and outside communicating door are both closed and locked, while open access is provided between the driver's left hand station and the second man's position to the right of the now full width cab.

It is the latter configuration that needs to be modelled.

First the central corridor zone is opened up cutting away the central part of the instrument and controls desk. Next an open side wall is constructed and fitted to the right hand side of the driver's position. Finally stub walls and floor complete the corridor as far as is possible towards the central outside door.

Unfortunately, the lighting PCB prevents the completion of the communicating door corridor behind the original central part of the desk. I don't want to hack the PCB, so I will endeavour to hide it in the shadows using matt black paint.

There is some danger of light from the front LEDs leaking into the cab and if this proves a problem, "black tack" mastic will be used to seal the offending light paths. 

A Noch driver (with arm repositioned) will be super glued to the seat in the power car cab.





The Modified Power Car Cab is shown below:

White LED glued to the roof before the cab is refitted


3. The Sound System:

Bachmann have attempted to provide provision to mount an ESU 40x20mm speaker in the floor of the lead car. However, if this approach is taken the rear of the speaker assembly will protrude into the passenger accommodation. I'm not an acoustics expert, but my limited experience suggests that it would be essential to provide a mastic seal around the edge of the speaker frame to fill in the 1mm gap between speaker and car floor, to prevent front to back cancelation effects. Also some form of rear venting through the passenger floor would be desirable. Bachmann provide an unsealed rear enclosure for the speaker which requires a removable section of the passenger seating moulding to be omitted. This rather defeats the main reason that the unit was redesigned..... i.e. to provide a more convincing interior to the power car!

So my present plan is to mount the speaker, within a standard ESU enclosure, on the underside of the trailer car instead. To keep the enclosure out of sight, behind the larger elements of the detailed underside parts, it will be necessary to recess the unit within a 22x42mm hole cut in the body underside. This will be much easier in the trailer car, which unlike the power car, has an all plastic underside. The speaker enclosure will not penetrate the seating moulding in this location. The down side is that an additional miniature 2 way wired connection between cars, will be required, but this is a simple job using a miniature TCS connector.  This approach should result in a well proven acoustic success, combining a sealed ESU 50334 speaker assembly, with Bryan's excellent Howes Class 150 sound project.


4. The Internal Lighting:

The Bachmann solution involves warmish white chip LEDs mounted, downward facing on the underside of a suspended (black) roof PCB. Two LEDs are used in the power car to illuminate the area not occupied by the motor housing, while three LEDs are evenly distributed within the Trailer car. Each LED runs at circa 5mA. I plan to paint the seats, install passengers and paint the underside of the suspended ceiling white, before making an assessment of the lighting quality. If its OK, I'll feed the LEDs from my standard anti flicker circuit, using an under floor capacitor.......... Its not perfect, but I think for now its good enough. A separately controlled white LED driver's cab light is also be fitted in the power car cab roof.

Wiring arrangements:

The anti-flicker circuit maintains normal LED brightness for about 1.5 seconds for the original interior lights. I've also experimentally added a couple of LEDs to give some lighting on to the motor case. Initially these LEDs simply use a series resistor, so will fade in brown out conditions. If successful, I may add another constant current source, to keep these at full brightness during brown outs. The 4 way connector wire colours are as indicated.

The LokSound decoder is below the yellow insulating tape.

A lot of the wiring is glued between the top of the windows and the roof.

The 1000uF 25Volt capacitor providing anti-flicker protection is hidden behind the under-floor detail.


5. Programming Lighting Control in the LokSound:

The lighting control will be as follows:

Control Button Function Function Outputs CV32 CV Check / Set
0 Running lights on Fwd: white on when F0 on & F15 off 2 CV321=20   CV325=8    CV330=1
0 Running lights on Bwd: yellow on 2 CV337=24    CV346=2
15 Night running Fwd: Aux 1 on when F0 on & F15 on 3 CV321=20   CV325=4    CV330=4
16 Internal lights Aux 4 on 3 CV341=16   CV346=32
17 Cab light Aux 2 on 3 CV357=64     CV362=8
18 Hazard lights Aux 3 on 3 CV374=1    CV378=16
19 All rears parking lights yellow on 3 CV390=4       CV394=2

Good, that all works fine!


A few pics of the power car under test:

(The Roof mounted Speaker will eventually go under the floor of the trailer car.)





Night running lights, cab light and internal lights on, plus door hazard lights in the lower pics.

The only disappointment is the experimental lighting in the motor section which is very dim.



The lack of light beside the motor casing may simply be because there is nothing for the LED to illuminate

So I've created a couple of low relief passengers from the Preiser pack and we'll try again.........................


Promising, but needs a bit more work!  Stop the light bleed through the plastic, warm up the

 pure white LED & improve its direction. Also paint the surfaces above window level and around

 the windows on the inside, yellow/white to remove the colour cast created by the blue inside plastics.


Well:  Successfully stopped the light bleed, but I don't think the white/yellow paint has helped much!

I've now added a sniff of yellow water colour paint to the LED diffusers & that's warmed up the LED light OK!


A few minor CV adjustments to improve motor control:

CV Orig value New value Comments
2 1 2 Increased to eliminate abrupt stop due to very slow first speed step
3 68 -  
4 39 -  
5 176 -  
6 68 -  
49 3 - (Already set to 40kHz)
51 0 -  
52 48 30 decreased to stop step 1 judder after CV55 change below
53 125 -  
54 48 -  
55 32 50 Increased to reflect perceived order of motor momentum
124 20 - (Already set to fixed frequency)


Summary of Function mapping:
Control Button Function
0 Running lights on
1 Engine Running
2 Two Tone Horn
3 Reversed Two Tone Horn
4 Single Horn Toot
5 Doors Close
6 Doors Open
7 Right Away Buzzer
8 Flange Squeal
9 Shunt Mode
10 Zero Momentum
13 Harrogate To Leeds Station Announcement
14  Leeds To York Station Announcement
15 Night running
16 Internal lights
17 Cab light
18 Hazard lights
19 All rears parking lights
20 Dispatcher's whistle


Bryan has kindly made some adjustments to the Howes sound project including the addition of a Dispatcher's whistle and the result is superb!

I've stood on the platform at York station, watching and listening to Northern Rail Class 150 units departing for Harrogate and Bryan's (Howes) decoder is spot-on!


Next the trailer car!.................................


The Trailer Car:

I had already fitted the ESU 50334 20x40mm speaker and its standard enclosure when this shot was taken and the clips securing the roof lighting PCB have also been removed.


Speaker close-up


Yup, did it again!

Well hidden by the battery boxes etc when on the track



Unfortunately the speaker protrudes by 3mm and the PCB clearance is 2mm.


So as I'm using my own circuit, I'll remove the centre of the PCB (between the lines scored into the underside).

This also leaves room for leaded resistors and diodes beside the speaker


Bachmann's voltage regulator goes too, although those two caps look useful!


I can see that there is room for 1000uF 25V anti-flicker cap for the lights in the roof, at the end joining the power car. I also have a location identified for the LokPilot FX V4 decoder. The mounting plate for my 21 pin version of the decoder will be installed inverted on top of the cab end of the internal lighting PCB, sandwiching this PCB between the mounting plate and the decoder. There is just room for the wiring below the upper body roof.



Trailer Car Running Lights:

I've tried a different approach to the white marker lights in the trailer car, which works rather better than my initial concept for the power car. This time I've tucked the white chip LEDs just out of sight, facing downwards, glued into the top of the moulded frame that surrounds the original Rear Light LEDs. I've painted the walls of this frame segment and the lighting PCB behind the rear lights, matt white. The rear lights work normally, beaming directly at the lenses, while the marker lights produce a weak white light, reflected from the PCB and frame walls, into the lens. The white glow is reasonably independent of viewing angle and simulates the blue-white light produced from the real dual purpose LED lamp, when in marker light mode.

Looking up at the forward running lights fitted to the chassis assembly, without the upper body shell.

(Running on reduced voltage to reduce glare.)


I've tested the unit when powered from an external DC supply with the upper body shell in place and optimised the resistor values in line with those now appearing in the circuit diagram located earlier on this page.

(The day headlight worked much better after I cut off a large glue blob from the rear of the lens in the upper body shell!)


Showing the chassis with the PCBs back in place and the running lights series resistors and diodes glued within the central area.

The wires are routed through holes in the seat moulding & will run (out of sight) up the wall sections into the modified lighting PCB assembly.


Close up of the resistors and diodes....plenty of room under the seat moulding!


Arranging the trailer car circuits:

This is how its evolved.


Trailer Car passengers come aboard for the first time:


Preiser seated figures glued in place


The populated seat moulding screwed back in place.


Inner Roof modifications:

Inner roof painted white, with constant current sources now feeding the Bachmann LEDs


Two PNP transistor constant current sources, with one of the LEDs on the left.

The 120 ohm emitter resistors are unpainted in case 5mA needs adjustment.


Putting the lower body & inner roof assembly together:

Inner roof clipped in place and wiring complete. The 4 way connector hooks up to the hazard lights and the interior lights stay-alive capacitor circuit,

which are both in the upper body shell.


The decoder is plugged into a 21 pin adapter board which is glued to the inner roof top.

If you use this ESU adapter board, beware of the solder pad numbers, which are numbered differently to the ESU decoder pin numbers in the decoder manual!

In the decoder, the missing index pin is numbered 11. However on the ESU adapter board, pad 11 is assigned to the next live pin, which is decoder pin 12!

21 pin version of the LokPilot FX V4 function decoder, plugged into the adapter board.


The connector sockets are glued to the top of the inner roof. If I've planned it correctly, the flying lead plugs from the upper body shell will dangle low enough to be plugged in, but will then fold back towards the roof as the two halves of the car are brought together. (Fingers crossed.)


Mind your head on the transistors when you get up!


While I wait for the non-cyanoacrylate glue bonding the first hazard light down, to dry........Time to think about programming the function decoder:


Control Button Function Function Outputs Mapping line CV32 CV Check / Set  (All other CVs in mapping lines=0)
0 Running lights on Fwd: yellow on 1(257-270) 2 CVA=20; CVK=2                        CV257=20; CV266=2
0 Running lights on Bwd: white on when F0 on & F15 off 2(273-286) 2 CVA=24; CVE=8; CVK=1            CV273=24; CV277=8; CV282=1
15 Night running Bwd: Aux 1 on when F0 on & F15 on 3(289-302) 2 CVA=24; CVE=4; CVK=4            CV289=24; CV293=4; CV298=4
16 Internal lights Aux 4 on 4(305-318) 2 CVE=16; CVK=32                       CV309=16; CV314=32
18 Hazard lights Aux 3 on 5(321-334) 2 CVF=1; CVK=16                         CV326=1; CV330=16
19 All rears parking lights yellow on 6(337-350) 2 CVF=4; CVK=2                           CV342=4; CV346=2

Second hazard light LED now in place and glue setting..... it takes about an hour!

Inside the roof....I hope it all fits!


Testing the trailer car operation:

The good news is that the upper body shell fits fine with the interconnect leads staying hidden in the roof as intended.

The bad news is that although the lighting functionality was exactly as planned, I found that the headlights did not switch completely off when the controller had set them to the off condition. Instead they display a faint but very visible glow when they should be off completely.

This looks like a hardware problem associated with the ESU 21 pin LokPilot V4. The function outputs are not switching fully off. The headlights seem to be the only function loads that show the problem, although there is also the faintest hint that maybe one of the rear lights also has a residual glow..... I'll take another look at that when night falls.***

I've used leaded versions of this decoder without any sign of similar issues, however I have a spare 21 pin variant which also displays the same problem when fitted on the 150.

I've fixed the problem by adding a 10k resistor between each headlight function output and the common positive, close to the 21 pin adapter board, above the inner roof.

*** In darkness, its clear that there is a faint residual glow in both rear lights and in the hazard lights, so for some reason, none of the function outputs are fully switching off!  I'll use the same fix on the yellow and brown function outputs as used successfully on the headlights. I've not come across this issue before, so I'm wondering if the wiring arrangements are creating the effect somehow, but I haven't thought of any explanation yet.  Fortunately, there is no hint of the effect in the power car. (After leaving the car powered up for an hour or so, the glow had stopped.)


Testing both cars, now coupled together:

Wow! The sound volume with the speaker mounted in the trailer car and pointed downwards is much louder than when it was being run in its temporary roof top location!  I need to wind it down a bit before my other half returns from a shopping trip with our daughter.

All seems to be behaving as planned, so I've fitted the obstacle deflector and BSI coupler to the trailer car (these are already on-board the power car). I'll Pop the screws back, then it will be time for a photocall:





Next a video !.................

First, Some Minor Programming Tweaks:

To save a bit of time, I've arranged for the hazard lights to come on when the door open sound is produced. I've also changed the original separate hazard light button assignments so that the trailer car uses key 22 instead of the original key 18. I can then keep the lights on in the rear car till the guard closes the door as the train moves off.

I've also added a volume fader via key 21, to minimise disturbance to the rest of the house while I'm working on the video schedule.

So the function mapping now looks like this:


Control Button Function
0 Running lights on
1 Engine Running
2 Two Tone Horn
3 Reversed Two Tone Horn
4 Single Horn Toot
5 Doors Close
6 Doors Open & hazard lights on
7 Right Away Buzzer
8 Flange Squeal
9 Shunt Mode
10 Zero Momentum
13 Harrogate To Leeds Station Announcement
14  Leeds To York Station Announcement
15 Night running
16 Internal lights
17 Cab light
18 Hazard lights power car
19 All rears parking lights
20 Dispatcher's whistle
21 Volume fader
22 Hazard lights trailer car


Right! That's got the demonstration schedule working on the PC, using Traincontroller software, so all I've got to do, is video it!


For the Demonstration Video: Click Here



Supplier website links:


Hattons of Liverpool    The new Class 150 unit above was pre-ordered from this excellent e-shop.
Howes Models    Source for Bryan's excellent sound project on the ESU LokSound V4
Coastal DCC    Source for ESU LokPilot FX V4 (6 output function decoder for the trailer car).
Digitrains    DCC specialist supplier based in Lincoln. Good range of pre-wired chip LEDs.
Maplin    Would give them a better rating if they included dimensions in their on-line electrolytic capacitor data (went to Amazon instead)!



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