Taking a 3029 to the heights...

Here is another conversion story. I own two different "two axle 3029", originating from starter sets in the late 60's. Plastic shell, no light, one rubber tire, coupling hooks, and no real prototype. Not the standards I currently can afford; however, old friends, and good looking (in my eyes: I mean the overall model, proportions etc).

Why do this conversion ? 

I tried a delta conversion before; straightforward and no problems; however a result which was even less impressive: the speed control was very jerky (it's a light model too) with only two speeds: "creep" and "run", it's extremely noisy. And rather sensitive to load; taking it "to the heights" need even more manual attention.

With the Intellibox I now have the opportunity to chose a DCC decoder instead; so I decided to use a Lenz LE130, together with an ordinary HAMO-magnet for this old SFCM motor. The cost in all was about DEM 100!  

What had to be modified ? 

Below you can compare,  "before/after" images. Below you notice the electromagnetic relay to the left, and the field coil to the right; both of which were replaced. On top of the motor, the black thing, is an inductance smoothing the current on it's way to the motor so it won't disturb your TV-set that much. The motor type is called SFCM, Small Flat Collector Motor, and is easily recognized in most elder small and midsize Märklin Locos.

Above there is the decoder to the left, and the field magnet is on behind. Here you see the field coil / magnet difference.

And here, a view from above

Additional modifications

I wanted to add light too. The problem here is to be able to remove the shell, without getting problems with the connection to the light. Here it was easy, the plastic shell was in one part, including the lantern imitations. The plastic was simply cut with a knife as you see below, holes were drilled in the lanterns and micro bulbs were inserted. The small part was fixed with double sided adhesive tape; in fact a part of the tape enclosed with the decoder.

The green thing is only my way of connecting the cables from the decoder with the cables from the bulbs, without having to solder to near the sensitive parts. In addition resistors had to be connected in series with the bulbs.

The result

Finished! I really was uncertain if it should be worth the effort; the jerky behavior could be because bad wheel contact; only three wheels with rail contacts. But it wasn't; for this very light loco speed regulation seems very important, especially in slow speed. The speed curve was preferably programmed; the factory defaults didn't suit the motor very much. You can't help it has only one rubber tire, and it's too light, especially in front however. And it seems that this motor doesn't like the PWM very much; it's still very noisy, even if it's possible to adjust the sound a little by adjusting the pulse width.