Locomotive Roster: Arnold 2471; SNCF BB 25201

Last Christmas I was happy to receive this dashing looking locomotive from the SNCF; an Arnold 2471  class BB 25200 number 25201.   I had spotted one of these a while back and there were three things that I really liked about it:

  • Despite the fact that its an older production model, details and graphics are very nice
  • I liked the white/orange/black paint scheme
  • I love the curved cab window styling on these French electrics!

The Arnold Model:
The Arnold model I have (#2471) was cataloged sometime between 1989 and 1994 and according to the database at Spurweite-N.  Given the time frame, this is obviously an analog model and will require conversion to operate on a DCC layout like mine!  Spurweite-N also lists a another version of this model (#82471) that allegedly was sold with a digital decoder installed. I find this fairly surprising (the available data for this supposedly digital version are the sames as my analog version.  While I don't dispute there was something like DCC around during the early 1990's I am a bit skeptical that Arnold would have sold an already digitized version.  It might be that the catalog dates for the digital version are incorrect and they reflect the early 2000's and not the '90's, which would be more believable).

The below photo shows the fairly impressive detail (in my opinion) for a model produced in the early '90's!
Don't confuse Arnold's model of the BB 25200 with their much earlier model of another and slightly similar BB 9200, which comes from the 1970's era and represents what I think would be considered rather crude detail, low quality graphics, and rudimentary mechanisms.  I'm basing this off of photographic comparisons which make the visual comparison fairly obvious, and I would expect the mechanical mechanisms to be fairly crude and representative of the first generation of N Scale models.

The Prototype:
The BB 25200 class was, and is, a bi-current locomotive able to operate on France's two main standards for electrical locomotives (1.5kv DC and 24kv AC - which is a legacy of France's pre-nationlization private railway standards before 1938).

These locomotives were produced for the SNCF between 1965 and 1975 and, from what I can tell, would pull both passenger and freight trains as necessary.

This electric locomotive, which I tend to think of as a 'box cab' given my American orientation, has some of the distinctive styling that I love about the SNCF - mainly those super-cool, styling curved window elements.  It reminds me of the sort of decorative flourishes' that were applied to cars, buildings, and all sorts of other engineered elements back in the 'old days'.
I'm also intrigued by the livery (another reason I enjoy the SNCF so much....despite being a state-run railway, the diversity of different liveries is pretty amazing, and most of them are pretty amazing and attractive!) which is described as the "Le Mans" livery.  I can't tell if Arnold did a good job or replicating this livery, the few photos I've found of prototypes in this scheme seem close, but something is not quite right.  I'm not too crazy about the precise shade, and being somewhat ignorant of the prototype helps to appreciate the model for what it is.  It is interesting, I can't tell if the base color is white, or more of a light grey? If it's light grey, then its very reminiscent of the current 'concrete' scheme that is frequently seen (grey with organge stripes).  So perhaps this livery was something of a predeccesor?

According to Wikipedia, many of these locomotives operated (and still do?) in the Rhone-Alpes region of France, which borders Switzerland and Italy, where the largest city is Lyon.
Perhaps not surprisingly, these locomotives have put in their time and many of them are being replaced by newer EMU's, Prima's and so forth.  Amazingly to me is that the last production of these was in 1975 and here, 35 years later, even a few are still in operation!

Converting to DCC:
As I mentioned above, despite the good quality of the casting and printing, this locomotive was produced before the idea of digital really took hold, so converting to DCC is somthing you'll have to do yourself (or pay someone, or find a friend!).

I was able to accomplish this using a tutorial on the French N Scale Forum, but as the original instructions are in French, I decide I would pass on the good knowledge I learned from this site and member "Oliv CTR" (Merci!) and contribute my own photos of the process.

One of the first things I learned from the French forum, is that there is not a lot of room for the decoder, so the thinnest decoder you can find is advised.  I used an Ulenbrock 73400 which is only 2.4mm thick and will fit nicely within the enclosure.
Removing the body is a little unusual, as you have to remove a screw from the bottom of the chassis, which releases the two plastic tank sections which then allow you to remove the shell.  Trying the remove the shell without remove the screw will probably wreck your locomotive.
Once the shell is off, you will see the PCB board, which is where most of soldering and digitizing operation will take place.  Remove the two screws which hold the PCB board to the chassis to work on the decoder install.  Once those two screws are removed, you can slide the PCB board off the motor contacts and metal base.
 Again, space is tight, so in order to add the decoder, something must be removed.  Following the instructions from "Oliv CTR" on the N Forum, I chose the same relatively 'blank' area as he did.  I don't really know if there are other options, but this location works well.  In the below photo, you can see some pencil lines where I planned my cuts.
A razor saw is a really nice tool for making sharp cuts in the PCB board.  I scored the bottom area of the cut-out area with a knife and was able to snap away the unneeded section of PCB.
One thing I've never done before (at least in the very few DCC conversions I've done myself) is to shorten up the wires prior to install.  My typical inclination is to assume that there will be enough room to hide excess wires away after everything is installed, plus I want the safety margin of extra wire...just in case!   Well with this loco there is no extra space, so I decided to shorten my wires before installation to get as little slack in the final install as possible!
The below photo shows the PCB board with the cut-out section for the decoder, as well as the PCB copper strip connection you will need to severe to the light and the diodes and capacitors that need to be removed.
With everything  but the white wire soldered, below is where the various wires get soldered.  While it may seem somewhat complex, being able to do all your wiring right on the PCB itself make this a fairly easy decoder install.
I chose not to replace the old-fashioned incandescent bulbs with LED's.  If you wanted to do that you would also need to find space for the resistors as well.

Putting the loco on the track, I'm always a little relieved that anything works that I have put a soldering iron to!  She runs nicely, if a bit noisely, which I attribute to a 20+ year old mechanism!

On the down side, the bulbs are extremely dim and the connections could probably use some cleaning as the light doesn't stay on consistently when in DCC mode.  The lights only work in one direction as well...hmmm....something to consider.


  1. If they are the bulbs of origin (thus for analogical), it is already surprising that they did not roast in digital (the voltage is more raised in digital than analog it seems to me)

  2. Hi Jerry,
    nice Review again and great pics, but I miss the video :)
    Regarding the question if Arnold sold the model with decoder in the 1990s, the only thing I fouund is a new release sheet from 1999 in which you can see models which were sold with decoder.
    For example here : http://www.nsesoftware.nl/vdweerdt_nl/manuals/arnol/catalogi/1999/neuheiten_1999_007.html
    the model 2440 is the normal version and 82440 is the version with decoder. Looks like a 5 digit number beginning with 8 was used for the digital version.
    According to this page (sorry, only in german) http://de.wikipedia.org/wiki/M%C3%A4rklin_Digital Arnold Digital was on the market since 1988!

    Greetings from Hamburg


  3. Hello Francis! My voltage to my tracks is just under 13volts, so pretty safe for me. I know that many starter sets for DCC have power up to 18v which would definitely be too high!

    Jorg: Thanks for the detective work! Interesting that Arnold was into digital that early! Wow! Thanks for the info!

  4. Hi Jerry,
    Thanks for the review!

    I think with a small SMD set at each end, you could solve your lighting dilemma (1 SMD resistor + 2 SMD Leds really don't require much space).

    In any case, firstly, thanks for the nostalgia! Though I think the BB25200s never ran where I lived, I am familiar with its follower, the similar looking 25500 series, which also served on local lines between France/Monaco/Italy on the Riviera. If I am not mistaken, a driver even allowed me to sit in his place during a station stop, when I was 8 or 9. I still remember the enormous amount of mysterious buttons ;-)

    Secondly, you raise a very interesting point by mentioning the different SNCF liveries. I always wondered how the SNCF managed to have so many different liveries at the same time: changes in policies too often? Not enough budget for full rolling stock overhaul?
    Now that I live in Germany, I am facing the much more standardized approach of the Deutsche Bahn: the only exception to the official "Traffic Red" ("Verkehrsrot") being ICEs... But since some lines are privatized here, there is still plenty colour diversity to observe.
    But the US also has a big variety of color schemes, many of theme quite interesting as well!

  5. Couple of comments. First, the solder joints on the red and black wires appear to be "cold", as it were—this could explain some of your issues, as such joints are generally unreliable.

    Second, you have the bulbs wired to the yellow and white leads—and the other side of each bulb? To the rails, I presume? If so, this results in an effective 50% /reduction/ in voltage to the bulbs, which will result in dimmer operation! But because what's actually happening is a 50% duty-cycle PWM (rather than an actual 50% reduction in voltage), you are going to get increased heat as well, so I would watch that closely.

    Does the Uhlenbrock decoder not have a blue common signal you can wire the bulbs to?

    Beautiful loco, though! And very clever installation work generally.

  6. @Pierre -Great idea about an SMD resistor! I hadn't thought of that, but those would work! Great idea!

    @Don - Hey Don! Yes, there's no 'blue' wire as we know from our standard color-coding, but I think Uhlenbrock uses the white wire for the common - I'll need to go check the manual. I think you may be correct, the rails are being used for the 'common', which as you point out is probably not great! Yeah, a few 'cold joints' - I think what that means (in this example) is that I've basically created a soldering joint onto older solder, instead of the contact. Hmmm...easy to clean up if that's the problem, but something I need to pay closer attention to in the future! Appreciate your insight and knowledge!!!!

  7. Jerry, I'll post an article to detail my "custom and dirty" SMD solution.

    I'm sure you already know all of this, in a few words:
    - Get a test electronic test board with stripes (like http://www.conrad.com/%28L-x-W-x-H%29-90-x-50-x-1%2e6-mm.htm?websale7=conrad-int&pi=530809)
    - Cut it to keep 3 stripes, and 2 or 3 vertical contacts (holes) (this usually fits in N)
    - Cut the middle stripe in two isolated parts. You now have one vertical stripe left, the middle stripe cut in 2 sections and one vertical stripe right.
    - Bridge the "vertical" gab of the middle with the SMD resistor
    - Solder 2 red/yellow SMD leds (horizontal bridge) between the middle and respectively the left/right stripe (make sure to place the leds as centered as the contacts allow for better light distribution).
    - Solder a cable on the "top" of the mini board, to each of the 3 stripes (yellow, ground in the middle stripe, and red) and connect them in your engine.

  8. Jerry, I think Francois has a good point. Even if the bulb is safe to 16V, and on your layout is getting a bit less than 12, that's still a lot more than the 4-6 it would see on a normal DC layout. Once you fix the wiring problem that has them at half intensity, they could be quite bright, and quite hot.

    There's also a risk that the power draw when the light first comes on (the inrush current, which can be 10x the normal) can damage the decoder without a resistor to limit it.

    The usual guidance is to put a 20-30 ohm 1/4 watt resistor in series with a bulb headlight when using a DCC decoder function output. Personally, I think you'd be better off with a 100-ohm 1/2 watt resistor, although that could leave the bulb a bit dim.