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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.

TCS M4 Decoder installation

Rolling stock Posted on Wed, June 30, 2010 16:56:02

I have now installed a TCS M4 decoder in the second U25B (SP 6702). I did the installation nearly in the same way as described for SP 6700 in the previous post. The difference being that this time I did not solder the gray and orange wires directly to the motor contacts. Instead I reused the motor contacts pads on the original light board, and soldered all wires to that board.

Here are a few pictures showing what I mean. The first one shows the light board with the part holding the rear LED cut off/removed (to the right in the picture). You can also see that the resistor and the diode for the front LED (to the left) has been removed, and that all internal board leads has been cut/filed off.

The next picture shows the same thing, but from the underside of the board.

If you look carefully you might also see two soldering joints – one on each of the two motor contact pads (the large rectangular shapes). Those solder joints are brass wires I added. They go right through the board. If you look carefully you may actually see them in the first picture as well. The idea was that the motor contacts should still touch the pads (as when the engine was delivered), and that the decoder wires should make contact with the pads throgh the new wires.

After having prepared the board as shown above I reinstalled it, but since I had cut all the leads on the board, nothing was in contact with anything else.

Now I could solder the decoder wires to the board. I started by soldering the red and the black wires (track power) to the right and left frame contact pads, and the orange and gray wires (motor) to the new brass wires coming up through the board. Before I soldered the wires in place I cut them to length.

The only thing remaining was to solder the blue and white wires to the front LED, with a 1 kOhm resistor in series, as shown in the last picture below.

The unused wires (yellow, green and violet) are tucked away under the decoder. And yes, the heat shrink tube around the white wire (near the decoder) is because I happened to cut it by mistake 😉

U25B Decoder Installation

Rolling stock Posted on Sun, June 27, 2010 20:14:48

I have some engines sitting in line waiting for decoders to be installed. Two of those engines are Atlas U25B:s. The other day I installed a TCS M4 decoder in one of those (SP 6700). A straigtforward installation where I reused the forward LED from the existing ligth board, but sacrificed the rear LED in order to get the decoder in. Here is a picture of 6700 heading out of the staging yard:

I think I mentioned in an earlier post that I had some problems with one of the staging yard turnouts. Some cars had a tendancy to derail when passing that turnout. I thought I had fixed that problem, but when test running SP 6700 and its new decoder the loco derailed on that precise turnout. Every time. But only when taking the straight route! When doing so it always climbed the point rail and the front truck took the divering route instead. I am not 100% sure but I think the problem was related to the spacing between the point rails. They seem to sit to far apart on this particular turnout. Anyway, I managed to make the problem go away by installing a pair of guard rails, as shown below:

I cut them from a piece of code 55 flex track, and glued them in place with CA.

Turnout test car

Rolling stock Posted on Sat, March 28, 2009 20:02:35

Since I am currently struggling with a number of handlaid turnouts, when time permits, I realized I needed a good way of testíng them. I wanted a test car that, when pushed across the turnouts, exposed as much as possible of the wheels and the rails. Since the tolerances required by a turnout very much depends on the type of wheels you intend to use on your cars I decided to build my car using Fox Valley wheels, which is the type of wheels I have decided to use for this layout.

This is what I used to build the car, and is stuff I already had at hand
– a pair of old trucks with Rapido couplers
– a couple of truck king pins
– a few washers
– a piece of Plastruct rectangular tubing for the beam.
– four Fox Valley wheels

I started by removing the Rapído couplers from the trucks. I then cut the tubing to the length of a 50 ft car and drilled a hole at each end, large enough to accept the king bin. Then it was simple matter of mounting the trucks to the beam (tubing), with a number of washers in between so that they would swivel freely, and then install the wheels. The complete project took no more than 10 minutes.

Here are a couple of pictures of the finished car.

Fox Valley wheels

Rolling stock Posted on Wed, February 25, 2009 20:53:50

While slowly working along with my curved turnout assembly I also try to find other small projects to get some variation. I accomplished one such project this evening.

Some time ago I bought some Fox Valley metal wheel sets. They are low-profile (have low wheel flanges) and come in some different flavors:

– Different axle lengths to fit different makes of trucks
– Different wheel diameters

I bought 33″ wheels with .540″ axles for Micro-Trains trucks and .553″ axles which will among other fit newer Atlas trucks. Today I set out to replace the wheels on my 50′ and longer freight cars (mostly boxcars).

I think the look generally improved and in some cases the cars also roll noticably better. Here is a photo of a flat-car with Fox Valley wheels on the left truck and the original Micro-Trains plastic wheels on the right truck.

The metal wheels look more distinct, and the wheel flanges are not that apparent. Click here to view a larger picture.

Bad decoder replaced

Rolling stock Posted on Mon, February 16, 2009 18:06:38

Today I got a replacement decoder from TCS, as a substitute for the bad one I wrote about in an earlier post. The new decoder went in straight away and now the engine works like a charm. I even had the time to MU it with another loco.

Too bad the decoder went crazy to begin with. A thing like that should not happen, but when it did TCS did what they advertised they should: No questions asked, no charge. Excellent.

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