DCC conversion for dummies - the general rule is....?

[quinntopia]

I have a general question related to converting a 'pre-digital age' locomotive (when DCC was only a glimmer in our eyes) from DC to DCC operation.  It seems to me, and I'm not sure, is that the challenge is that most 'pre-digital' locomotives were designed with some elements of the frame, ballast or other materials, as the 'ground' for the locomotive.  This makes it tricky as you need to isolate this former 'conduit' from everything as you'll wind up with a massive short with the decoder. 

 

This is because: All electrical contacts (connections from track, to decoder, and connections from decoder to lights and other functions) must be isolated (duh!).

 

Have I go this right? 

 

The reason I ask is that I have some older (near junkers) and some unused decoders that I want to have some fun with.  As I read some of the online tutorials for these locomotives (1970's era Minitrx), the photos and descriptions are either so specific to just that model I'm uncertain if they work for the particular model I have, or they are just plain confusing.

 

I am thinking that if my statements above are correct (1. Pre digital locomotives used the frame or anything that could conduct electricity as one of the conduits for the DC signal, and 2) with DCC its critical that all of these connections be removed and the only conenctions that remain must be isolated and go to, through, and from the appropriate contacts on the decoder) then I can probably pretty much figure out how to 'convert' any locomotive.

 

Can anyone clarify or correct?

 

Thanks for all the help!

[Martijn Meerts]

It depends on the model really. Quite a few electric and diesel locomotives use the frame as ground. In the case of the European brands, they still use that technique for most electrics and diesels these days.

 

Steam locomotives tend to have separate pickups from the wheels, 1 is postive, 1 is ground.

 

Several of the newer locomotives use the same split-frame construction as nearly all Japanese locomotives. 1 half of the frame is positive, the other half negative. While this sounds easy, the frame is made of a metal that distributes heat quite effectively, making soldering on the frame directly very difficult and unreliable ;)

 

Some pictures might help a bit more, I've converted several old Minitrix, Fleischmann and Arnold locomotives.

[quinntopia]

Thanks for the offer Martijn!

 

Here's some photos, and I expect you might know quite a but about this locomotive than I do! (It seems to be an NS 1100 series, which I picked up on eBay recently - the paint is in very sad shape which means this either gets massive weathering or a repaint, but first, need to convert!).

 

Here's an 'overview' of where I am now...

 

Here's a detail shot of the bogies (yes, look at that grime ;D!  I fully plan a thorough bath and lube job before this ever sees power again!).  As you know, the two brass strips sticking up from the bogies contact the bottom of a small circuit board that sits below the frame and the motor. 

 

Here's a shot of the underside of the frame showing the small circuit board where the above brass contacts make contact.

 

Skipping past the motor, two leads soldered to the small circuit board go to the 'large' circuit board, shown in this photo.  The only purpose I see for this large circuit board is to allow power from cantenary and to transfer power to the bulbs (it seems the bulbs get the opposite polarity from the metal frame).  There are two 'bracket' like contacts that snap inside the actual motor that seem to complete contact between the large top circuit board and the motor.

 

And then, the motor itself:

 

I think that's about it.  I think (but am by no means confident) that buy just isolating the power contacts from the bogies from the frame, sending those power inputs direct to the decoder, then use the motor out leads from the decoder to the motor, and setting up new LED lights (again, direct from decoder and remove all contact with the frame), I should be good.  But, then, my confidence here is about 10%, so any help is greatly appreciated!

[Martijn Meerts]

Interestingly enough, I have this very same loco, except in the more modern grey/yellow colour scheme. Of course, minitrix got the grey and yellow wrong compared to the prototype, but ohwell ;) The loco's weren't common with the flat nose, very few of them ran in Holland, I think most of them went to England.

 

Anyway, the loco is built very common, many Minitrix loco's are like that. I converted a similar loco just a few weeks ago in a matter of half an hour or so.

 

In short though, I cut the copper lanes on the circuit board to isolate the motor and lights, and soldered the decoder wires directly to those copper lanes. There's no need to do anything with the bogies at all.

 

I'll get back to you about it tomorrow, I'm gonna have to check my own version of the loco. It's slightly different from the one you have, and I'm actually not sure that green wire is originally there. On my version I have a switch to change it from wheel powered to catenary powered.

[quinntopia]

Thanks Martijn,

 

Glad to hear the process is fairly simple! Please let me know anything else about your conversion!  In truth, what you describe seems a bit too easy!  :)  Did you replace the bulbs with LED's?  As you can see from my photos, the ground (or negative current, not sure what to call that leg of polarity) for the bulbs seems to come from the metal frame.  Where did you put the decoder? I was planning on milling out some of the metal chassis or perhaps getting rid of the top circuit board altogether, but am not sure.  Your assistance is greatly appreciated.

 

As for paint, this paint scheme seems to be very early version for the NS, but its colorful and quite striking:

[Martijn Meerts]

Hmm..  Could you take a picture of the main circuit board from the top, so it's a bit better to see where all the wires go?

 

The one I converted was a different loco, but was built the same. It was quite a bit longer and had a nice little pocket in the bottom of the loco which fit the decoder.

 

The loco belongs to my father, but since I'm visiting my parents back in Holland the next 2 weeks, I'll take some pictures of that one and post them. Finding room for the decoder in the 1100 might be an interesting project =)

 

 

As for the light blue version on the last picture, that's the original one. After that came the darker blue (the one you have), and after that again a mainly grey one with a yellow stripe, the same colours as the "Sik" in the picture here (the little shunting loco)

[quinntopia]

Here's another view of the top of the circuit board

 

So, the little switcher in Holland is called a "Sik"?  The little switcher in Germany is called a "Kof"?  "Sik and Kof"....is that an intentional pun?  ;)  What do the Belgians call theirs?  ;D

[Martijn Meerts]

That specific switcher is called a "Sik", or at least, I think it is. There's multiple version with different names etc. "Sik" is Dutch for "goatee", nothing to do with being ill ;)

 

 

As for your model, it looks like it has been altered a bit by a previous owner. It seems to be missing the switch that allows you to select catenary powered or wheel powered. Anyway, I'll take a picture soon of the loco I converted recently, but unfortunately I'll have to wait a bit with actually figuring out how to convert your model. I'm leaving for Holland right after work today, so I don't have access to my model of the 1100 for about 2 weeks.

[Martijn Meerts]

With a bit of a delay, here's a picture of an install I did in a German V200. Generally, the construction of the locomotive is pretty much the same as the 1100. The circuit board looks different, but functions in exactly the same way.

 

The decoder is located in the bottom, below the motor. In the case of the V200's, there's a good amount of space there.

 

White and yellow wires are lights, orange wire is motor, grey wire (you can just see it next to the white one) is motor as well, and not visible are red (power pickup from the wheels) and black (connected to the frame of the locomotive.)

 

Not exactly the 1100, but it might help a little bit at least.

[quinntopia]

This is really helpful Martjin, Thanks!  I'm going to try and find some time this weekend to work on this!