Lennart's Model Railroad Blog

Lennart's Model Railroad Blog

About this blog

This blog is about my current model railroad layout project; The N scale "Summit" layout, which is a freelanced interpretation of the Southern Pacific Tehachapi tunnels and their surroundings. Or at least, that is what it is meant to be. What it will turn out to be is another matter. The banner photo above shows what I want to recreate in N scale.

Two decoders installed

Rolling stockPosted by lennart Sun, January 25, 2009 19:02:27

Nothing to show has really happened on the layout during the last few days. I have glued the turnout I have been working on lately in place and started laying some track leading up to it. That track is far way in a corner and is hard to reach. So getting the tie plates in is a little (understatement) tedious.

So I turned to decoder installation instead.

I have done the two GP38s from Life-Like. These engines are not quite DCC ready. Well, they have a split frame mechanism, but the motor does direct contact with the frame halves. So that had to be changed.

On top they have a PC (Printed Circuit) board with a LED in each end. I intended to reuse the LEDs, and the PC board itself as a holder for the LEDs.

I simply removed all resistors and capacitors from the PC board, and also made a few cuts in the foil. This effectively isolated the LEDs and also supplied me with some empty soldering pads where I could attach the decoder's power pickup wires.

After some practical tests I also decided to replace the LEDs, since the light from the factory installed ones was barely visible. I replaced them with brighter LEDs I happened to have lying around. They are perhaps a little too white and bright, but I like that better than lights that do not show unless you turn off the layout overhead light.

Once the PC board was stripped and the LEDs replaced the rest was fairly straightforward:

- I soldered the motor wires (gray and orange) to the motor contacts, and put some tape over the contacts so that the motor would no longer make contact with the frame.
- Soldered the power pickup wires (red and black) to points on the PC board that still made contact with the frame.
- Soldered a 1000 Ohm resistor to each LED, and the decoder's common function wire (blue) to each other LED leg.
- Soldered the white wire to the forward LED resistor and the yellow wire to the rear LED resistor.

After having some difficulty figuring out the TCS way of dealing with light function CV programming I finally managed to make my F1 button to turn the headlight on and off, and the F2 button to control the rear light.

Both engines run well but one of them makes some kind of mechanical noise. I have not had time to troubleshoot that. This was the first decoder I did of these two and I did not cut the wires very short. So I ended up with quite a bunch of wiring on top of the decoder. I tried to keep them out of harms way with the help of some tape, but maybe it just became a too tight fit for the body shell, since the frame does not seat properly at the rear end. I will redo the wiring on that one and hopefully the problem goes away. Any ideas anyone?

The second two function wires are unused for now. I have this wild idea that I’ll some day try to have oscillating top lights and a steady head light down on the cab. That would require two decoder functions in each direction. I do not how to accomplish this. It would probably require miniature LEDs and optical fiber. Or I might install a beacon on the cab roof. Anyway, that is why I wanted some extra function outputs.

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