Rebuilding Märklin 3417, NSB 63a 2770, to digital with Märklin conversion set 60901 and mfx sound decoder 60931

Updated 06.06.2013

Märklin 3417, NSB 63a 2770
During the second world war the Germans brought 74 of their Br 52 to Norway.  When the war ended, the locomotives remained in Norway and was used by NSB.  This was a very valuable addition to the existing locomotive park, and gave NSB more time to supply new Diesel locomotives.  The last NSB series 63a retired November 9th 1970.

Preparations for the conversion:
I always start by removing everything; the reversing unit (in the tender), the motor and all the wiring, including the wires to the front lamp and smoke generator contact tongue.
Normally I separate the locomotive and the tender during the conversion.  It should not be necessary in this case.
Make sure that all the mechanical parts, like the gears, axels, rods and other moving or rotating parts works perfect before starting to install the new parts, in the following sequence:
1. new motor
2. decoder with the wiring and speaker
3. cabin light

The motor parts from the Märklin conversion sets 6090, 60901, 60921 and 60760 may be used.  Basically, only the decoders are different in these sets.  The new motor set 60941 suits perfect.  In this case the conversion set choise doesn't matter, as a separate mfx sound decoder, Märklin 60931, is used.  Installation of the motor itself is very simple. After removing the old motor, make sure that the mechanical parts are clean and work perfect.  Axels, rods and gears must rotate smoothly.  If necessary, oil the moving parts very carefully.  After installing the new motor, without the brushes, check again that it all rotates perfectly.  Then install the two brushes.  The below photo also shows the orange and brown/green wire to the interior light connector.

Decoder and speaker:
I stripped the decoder for it's rubber cover and glued it with a green detachable stuff to a decoder holder, Märklin part number 258820.  This holder fits in the tender tub.  I glued the two noise suppressors for the motor in the bottom of the tub, under the decoder holder.  The orange wire from the decoder is soldered to a distribution pcb (Printed Circuit Board) glued to the RH inside of the tender tub.  The orange wire is distributed to the rear lamp, the front lamp and to the connector for the interior light in the locomotive.  Also the brown ground wire has a distribution point on the pcb.

The speaker is installed where the cylinder shaped weights used to be.  By cutting off most of the centre divider and filing off a little bit of the speaker plastic house, it was possible to press fit the speaker house into the coal box.

The decoder functions:
See below table.

Front light and steam generator:
The grey wire from the decoder goes all the way forwards to the front lamp, with an orange wire.  These wires are soldered to the lamp holder.  Also the brown/red wire for function f1 goes all the way forwards, soldered to the contact tongue for the steam generator.

Tender weights:
To keep the good running performance, I had to put the removed weights back in the tender.  I fixed them together with insulating tape and just put it on top of the rear lamp.  It is held into position by the rear wall and the lateral divider.

Interior light in driver's cabin:
A small 28 volt T1 bulb is glued to the rear end of the driver's cabin ceiling, indicated by the gray arrow. The wires go through a slot in the RH side of the driver's cabin.  The connector is glued to the locomotive body. A 330 Ohm resistor is soldered to the connector, to reduce the voltage to the bulb, to reduce the light intensity.

My setting of the decoder:
Decoder settings, 3417 Default Mine
Analogue settings:
  Enable analogue mode check <
Starting voltage 7,300 <
Maximum voltage 23,000 <
Control settings :
  Swap directions uncheck <
Max. speed 255 80
Min. speed 4,000 <
Acc. time 7,000 20,000
Dec. time 3,750 20,000
Forward trim 1,000 <
Reverse trim 1,000 <
Motor settings:
  Motor PWM-frequency:
Low frequency uncheck <
High frequency check <
Load Control:
Reference parameter 11,300 <
Control parameter K 60 <
Control parameter I 120 <
Control influence 255 <
Special options:
  Preserve direction check <
Persistent acceleration uncheck <
Persistent speed check <
Persistent functions check <
Sound settings:
  Volume 255 155
Driving Sound Rate:
At min. speed 1,000 <
At max. speed 1,512 <
Random Sound:
Min. gap 30 15
Max. gap 50 <
Braking Sound Threshold 14 18

My Märklin 3417 NSB 63 2770 decoder functions:
3417 NSB 63a 2770
mfx 60931 Light Smoke
Bell Air
funct. dir. front rear short long 1 2 3
f0 forward                                  
reverse   2
f1 both     on                              
f2 both       on                            
f3 both         on                          
f4 both           on                        
f5 both             on                      
f6 both               on                    
f7 both                 on                  
f8 both                   on                
f9 both                     on              
f10 both                       on            
f11 both                         delay off off        
f12 both                             on      
f13 both                               on    
f14 both                                 on  
f15 both                                   on
Stop forward                                    
reverse       on                            
Drive forward                                    
reverse             on                      

Screenshot from my Central Station 1:

To the left  Märklin 3417 NSB 63a 2770, to the right Märklin 37158 NSB 63a 2843 with original mfx sound decoder

Some prototype information about the DR Br 52, from Wikipedia
Number(s): see Wikipedia text
Quantity: More than 7000
Manufacturer: see Wikipedia text
Year(s) of manufacture: 1942 - ca. 1950
Retired: ČSD: 1976
DB: 1962
DR: 1988
NSB: 1970
ÖBB: 1976
Axle arrangement: 1'E h2
Type: G 56.15
Gauge: 1,435 mm
Length over buffers: 22.975 m
27.532 m (with condensing tender)
Overall wheelbase: 9.2 m
Service weight: 84.0 t
Service weight incl. tender: 102.7 t
Adhesive weight: 75.9 t
Top speed: 80 km/h
Indicated Power: 1,192 kW (1,621 ps)
Driving wheel diameter: 1.4 m
Leading wheel diameter: 0.85 m
No. of cylinders: 2
Cylinder bore: 600 mm
Piston stroke: 660 mm
Boiler Overpressure: 16 bar (1.6 MPa)
Grate area: 3.89 m2
Evaporative heating area: 177.83 m2
Tender service weight: 18.7 t
Water capacity: 27,000 l
ÖBB covered tender = 30,000 l
Fuel: 10.0 t
Train heating: Steam