Updating a second Network Rail Bachmann Class 57/3 locomotive, this time, using a Legomanbiffo sound project on a LokSound V4 sound decoder.



The earlier conversion used a Zimo decoder, conveniently equipped with 8 function outputs. This time, I'm going to try the Legomanbiffo sound solution, which is only available on the LokSound V4 decoder type. For my lighting plans, I need 7 outputs, so I am going to use an additional TCS FL4 function decoder, to supplement the 4 conventional outputs available on the LokSound.  The speaker location will also be changed from below the roof fans (as on the previous 57/3) to the fuel tank/battery box (as already used successfully on my earlier DRS Class 57/0 locos.)

This project summary will cover the new LokSound/FL4 aspects of the conversion, with references made to the earlier summary for the lighting mods.     (Click here to see the Zimo 57/3 Project)

Class 57/3 in Network Rail livery.


The original Bachmann 57/3 Circuit diagram (showing approximate locations of the circuit elements):



The modifications proposed to use a 21 pin LokSound V4 plus a wired in FL4 function decoder:



Removing the original motor suppressor capacitors:

To facilitate 40kHz motor drive frequency, it helps to remove these capacitors (which are not required for DCC operation).

However, new plasticard insulators were required as the capacitor directly across the two motor contacts also held the motor contacts away from the metal chassis block. When the capacitor was removed, one of the contacts sprung backwards making solid electrical contact with the chassis block..... until the new insulators were fitted!


Adding a 40x20mm ESU 4 ohm speaker to the fuel tank/battery box moulding:

Speaker glued and sealed in place.


Producing the new lower marker light and replacement rear light assemblies:

View through the magnifier.


Close-up of the plasticard mounted assembly.


Underside view of LED assembly in place


Upside-down front view of the whole lighting assembly


Wiring under way...... just trying to decide where to locate the FL4!


Planning the button mapping:

The FL4 function decoder can only be controlled by buttons 0 to 12, so some re-arrangement of the button functions on the sound decoder will be necessary to free up space for the lighting control. To minimise the changes needed, the lighting control will be arranged so that button 0 activates the directional lights at the driver's end and button 10 activates the directional lights at the other end. (Pressing buttons 0 and 10 simultaneously activates the lights at both end of the locomotive.) If button 11 is not pressed, day running lights will be seen. If button 11 is also pressed, then night running lights will be seen.  Finally button 8 will activate the driver's cab light.

Decoder Function Output Wiring:

LokSound V4:

                White: day H/L & markers end 1

                Yellow: day H/L & markers end 2

                Green: night H/L & markers end 1

                Purple: night H/L & markers end 2

FL4:         Green: rears end 2                             continuous forwards only

                Purple: rears end 1                            continuous reverse only

                Brown: cab light end 1                     continuous both directions


Lights programming between the two decoders:


Button actions LokSound Decoder Function Output FL4 Decoder
F0 (Fwd)    &       F11 off  F(H/L) white no action
F0 (Fwd)    &       F11 on  Aux 1 green no action
F0 (Rev) no action purple wire
F10 (Fwd) no action green wire
F10 (Rev)     &     F11 off F(rear) yellow no action
F10 (Rev)     &     F11 on Aux 2 purple no action
F8      (Fwd or Rev) no action brown wire


Original Legomanbiffo LokSound button assignments and change summary:

Function Button Mapping line Original Assignments Sound Slot Original Volume New Button Assignments (change areas in blue) New volume settings
0(Fwd) 5 White     (Make Fwd+F0 on+F11 off) End 1 Day lights Fwd (white)  
0(Bwd) 6 Yellow     (Make Fwd+F0 on+F11 on) End 1 Night lights Fwd (Aux1)  
1 7 Engine prime/start/stop 1 & 2 128 & 60 Engine prime/start/stop  
2 8 Playable High Note Horn 23 128 Playable High Note Horn  
3 9 Playable Low Note Horn 24 128 Playable Low Note Horn  
4 10 Buffer Clash 4 100 Buffer Clash  
5 11 Air Release 5 70 Air Release  
6 12 Drivers door slam 6 110 Drivers door slam  
7 13 Compressor 7 90 Compressor  
8 14 Spirax Valve Popping 8 40 Cab Light (Driver end only)  
9 15 Flange/Wheel Squeal 9 128 Flange/Wheel Squeal  
10 16 Despatch Whistle 10 50 (Make Bwd+F10 on+F11 off) End 2 Day Lights Bwd (yellow)  
11 17       (Make Bwd+F10 on+ F11 on) End 2 Night Lights Bwd (aux2)  
12 18 Roof Fan/Cooler Group 12 120 Roof Fan/Cooler Group  
13 19 Sanders 13 60 Sanders  
14 20       Spirax Valve Popping (SS8)  
15 21       Despatch Whistle (SS10)  
16 22          
17 23          
18 24 Detonators 18 128 Detonators  
19 25 Aux 1        
20 26 Aux 2        


Changes Proposed to clear F8 (cab light), F10 (end 2 lights) and F11 (day/night headlights) & disable Aux1 & 2......

F8 Spirax Valve Popping.  Move to F14

F10 Despatch Whistle. (Where Applicable) Move to F15

F19 Aux 1 to new lights

F20 Aux 2 to new lights

To make any sense of the following, please refer to the ESU LokSound V4 manual (function outputs section).

First check the sound slot numbers in CVO & CVP for F8, F10 & F11:

Function button Programming Line CV Letters CV32/CVnumbers CV values Sound slot
F8 14 CVO 2/478 128 8
F10 16 CVP 2/511 2 10
F11 17 CVO, CVP & CVQ 3/270, 3/271 & 3/272 all zero none


 Then ..... Removing the original actions:

Function button Programming Line CV Letter & value CV32/CVnumber
F8 14 CVO=0 2/478
F10 16 CVP=0 2/511
F11 17 already zero no action req'd
F19 25 CVK=0 3/394
F20 26 CVK=0 3/410


and.... adding the sound slots to the new buttons:

Function button Programming Line CV Letter & value CV32/CVnumber
F14 20 CVO=128 3/318
F15 21 CVP =2 3/335


LokSoundV4 Lights Programming:

Function button(s) and direction Programming Line First CV Letter & value CV32/CVnumber Second CV Letter & value CV32/CVnumber Third CV Letter & value CV32/CVnumber
F0 on and  F11 off,  forward only 5 CVA=20 2/321 CVD=8 2/324 CVK=1 2/330
F0 on and  F11 on,  forward only 6 CVA=20 2/337 CVD=4 2/340 CVK=4 2/346
F10 on and  F11 off,  reverse only 16 CVA=8 2/497 CVD=9 2/500 CVK=2 2/506
F10 on and  F11 on,  reverse only 17 CVA=8 3/257 CVD=5 3/260 CVK=8 3/266

All other CVs in these programming lines should be set to zero.


FL4 CV Programming: (See TCS comprehensive programming manual for the details)

CV Number Description CV Value
51 Green wire forwards only 0
52 Purple wire reverse only 16
53 Brown wire both directions 32
35 Green wire on via F10 0
37 Green wire on via F10 32
36 Purple wire on via F0 2
38 Purple wire on via F0 0
39 Brown wire on via F8 0
41 Brown wire on via F8 8

Excellent!  That all works fine!


Completed chassis assembly, now including the FL4, taped along the centre line.

End 1 Lighting Photos:

Day running lights (F0, Forwards)


Night running lights (F0 + F11, Forwards)


Cab light on (F0 +F11 + F8, Forwards)

Rear lights on (F0, Backwards)



Improving the Motor CV settings:


CV Number Purpose Adjustment reason Initial value Final value
2 Start volts   1 1
3 Acceleration delay   170 170
4 Deceleration delay   89 89
5 max speed setting (ratio with 6 below)   210 210
6 half speed setting  (ratio with 5 above) Reduce to 1/3 of setting 5 to extend low speed control range 105 70
49 20kHz/40kHz operation   19(=40kHz) 19(=40kHz)
51 Very low speed motor inertia setting Small entry here eliminated hesitation on speed step 1 0 5
52 Very low speed loop gain Gradually increased to 50 to clear hesitation on speed steps 2-4 18 50
53 Reference voltage: adjust for req'd max speed Max speed looks OK 85 85
54 Loop gain for speed range except very slow   67 67
55 Motor inertia for speed range except very slow Looks much too low for twin flywheel medium size motor 18 100

With the original settings, performance was just about acceptable except for a hint of hesitation as the loco initially moved off and when in the final stage of a stop.  Might have been imagination, but medium speed may also have been not entirely smooth. The high acceleration delay tends to partially mask these effects, so before tinkering with the motor CV values, I programmed button 19 with the ESU zero inertia setting, which drops CV3 and CV4 to zero. (Set CV32=3 then CV396 to 1)

Having removed the acceleration and deceleration delays, I was able to explore the speed range on the small test track. Maximum speed looked about right so the CV 53 setting looked fine. However, the lowest speed steps had quite a larger separation, so I reduced CV6 to 1/3 of the CV5 value (from its original linear 1/2 value) to expand the lower speed parts of the control characteristic. This had the required effect.

In my limited experience, the ESU automatic optimisation routine that Bif recommends, can end up homing in on a non-ideal solution. In particular, CV55 should relate to the motor and flywheel mechanical inertia. The 3 pole Bachmann 57 motor with twin flywheels looks to me as if a figure of around 100 should be more appropriate than the very low 18 figure as received. So this was my starting point. (CV55 from 18 to 100.)

This single change (as would be expected) , made performance somewhat worse, by extending the range of low speed steps suffering from hesitation. However, gradually increasing the low speed loop gain via CV 52 progressively improved performance up to a new optimum value of 50, leaving just the first speed step now showing hesitation effects.

This was eliminated by a very small increase in the low speed inertia CV51 setting from zero to 5.

Motor control is now silky smooth and restoring Bif's CV3 & 4 to their original values by releasing the F19 key, loco performance is now superb with super smooth initial acceleration and final deceleration to a standing stop!  


Legomanbiffo sound driving characteristics:

Locomotive power levels, during acceleration and steady speed, depend on the speed set for the locomotive, with transition thresholds as follows on my system (and with my decoder settings):

Static: slow idle

At start scale speeds below 35mph: Builds up to notch 1 on take-off, then relaxes back to a fast idle speed.

At steady scale speed between 35 and 50mph: notch 1

At steady scale speed between 50 and 72mph: Notch 2

At steady scale speed above 72mph: Notch 3

Max scale speed is set at 90mph

However, the acceleration delay (CV3) is set quite high, to provide realistic acceleration rates even if the speed control is abruptly increased. If the initial speed setting is less than circa 35mph, the locomotive responds by initially winding up the power level to notch 1 immediately before moving off, then without any further operator interaction, after the initial acceleration, the power level drops back to a "high idle" for subsequent movement (Ideal for light engine movements in the yard). When the locomotive is stopped, the revs drop back to a lower static idle level. If the initial speed setting is higher, e.g. 60mph, then the locomotive quickly winds up its power level through the range to notch 2 as it moves away, and holds this level as the locomotive gradually accelerates up to its cruising speed. (Ideal when hauling a heavy train on a run along the main line.) For a white knuckle ride around the main track circuit, notch 3 is achieved with a scale speed setting of circa 72mph plus.

The revs drop back in a manner that seems very realistic as the throttle is brought down. The deceleration delay set by CV4 is around half of the acceleration delay, but is still long enough to require that the operator reacts well ahead, if approaching any kind of threat.


Function Button Assignments
0 End 1 Running Lights
1 Engine prime/start/stop
2 Playable High Note Horn
3 Playable Low Note Horn
4 Buffer Clash   (Only on the move)
5 Air Release
6 Drivers door slam
7 Compressor
8 Cab light (End 1)
9 Flange/Wheel Squeal   (Only on the move)
10 End 2 Running Lights
11 Off = Day Running Lights; On=Night Running Lights
12 Roof Fan/Cooler Group
13 Sanders
14 Spirax Valve Popping
15 Despatch Whistle
18 Detonators
19 Zero inertia (sets CV3 And CV4 to zero)

Final Function Mapping Table


Next the video:

The Class 57/3 has now been added to the locomotive list in the Traincontroller software on the computer and I've created a short routine on the test track, which involves some slow speed shunting moves to pick-up an independent snow plough, followed by a full power acceleration down the test track with the snow plough in tow. Appropriate changes to the running lights are made during the manoeuvres.

Click Here for the Youtube Video


A few issues discovered during video production:

1) A complication due to the use of a function decoder to supplement the main LokSound decoder:

If the locomotive is stopped and reversed under computer control in shuttle mode, the reverse direction command is sent after the locomotive receives the stop command, but before it actually comes to a halt. (Due to the braking delay programmed in via CV4). The FL4 function decoder changes the rear lights immediately, but the LokSound decoder waits until the loco comes to a halt, then changes the front lights. This results in a time delay between rear lights off and forward lights on at the rear of the train.... not really a big problem. But.... at the front of the train, the rear lights come on several seconds before the front lights go off and this definitely looks wrong!  The problem was overcome by changing the computer schedules to ensure that the loco comes to a halt before a direction change instruction is sent. (In Traincontroller, two schedules were coupled together to replace the original shuttle schedule and this enabled a delay to be placed at the appropriate place.

This is a good reason to either use Zimo decoders for full light control or to add buffer amps and use the two logic outputs on the LokSound V4, so that all primary light functions are under the control of the main decoder. Another lesson learned!

2) Half way through the video production, the TCS FL4 decoder in the snowplough, lost its ability to monitor direction on all function outputs. This fixed the outputs in a "rear of the snow train" configuration. I had to replace the decoder to fix the problem. Very odd as its behaved fine since first installed in the plough several years ago!    I just hope this isn't the beginning of a mid-life failure problem with all my other FL4 decoders..... They are used in a lot of my locomotives.... in particular the DMUs!


Adding buffer amps to eliminate the headlights / rearlights timing issue:

A pair of N-channel MOSFETs are added to the main PCB, connected to the 21 pin connector Aux3, Aux 4 and ground pins. The rearlight switching lines are transferred from the FL4 decoder to the drain terminals on the two new MOSFETs. (Aux3 controls end 2 rears; Aux4 controls end 1 rears).


Some changes to the LokSound decoder programming are also required:


Function button(s) and direction Programming Line First CV Letter & value CV32/CVnumber Second CV Letter & value CV32/CVnumber Second CV Letter & value CV32/CVnumber
F0 on ,  reverse only 39 CVA=24 4/353 - - CVK=32 4/362
F10 on,  forward only 40 CVA=4 4/369 CVD=1 4/372 CVK=16 4/378

The original FL4 rearlight outputs are made safe with the wire ends insulated but any FL4 programme changes will await any additional function requirements.


Supplier website links (These will be added to as the project progresses):

(Click in column below)

Rails of Sheffield    Very efficient!  The Bachmann model arrived the day after placing the order despite using the standard rate post option
DC Kits & D&E Videos    Source for Legomanbiffo sound projects on ESU LokSound V4 decoders
Digitrains    Helpful source for DCC components such as the Nanolight pre-wired chip LEDs.
ESU Website    For access to the 2013 user manual
Rapid Electronics of Colchester    A good reasonably priced source for electronic components.
Trains 4 U Peterborough    My nearest real railway model shop and source of the FL4 function decoder
Maplin    Useful local source for electronic components such as the stay alive capacitors


The photos of the model were taken using a hand held Canon Ixus 220.    


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