KB226: Electrical Paths in older locomotives

This article was last updated on Jan. 13, 2012, 9:23 a.m. | Print Article | Leave Feedback

I have an older Rivarossi Heisler that I have just installed a decoder in.

I have 2 other Rivarossi engines, older, with decoders in them and they work.

I use them as a template.

Anyway, I can't get the Heisler to run.

I have the orange wire at one side of the motor and the gray at the other.

The red is soldered to the frame and the black is connected to the front screw where I disconnected the light etc.

I just soldered the wires together.

The motor is OUT of the frame so no short can happen.

Can you help get my engine running?

The fact that the motor is isolated but you cannot get things running indicates that either the motor itself is inoperable or that the connections made to the frame are incorrect.

We have received periodic comments about locomotives from that era and problems with conversion to DCC.

The designers of locomotives from that time could never have known about the design requirements for DCC.

The most basic is that the motor be isolated, which you have done by removing it from the frame.

In this situation, there is obviously not a clear electrical path to the rails.

It also is possible that the Heisler design is different from other Rivarossi designs; this is not as odd as it may sound.

Since the locomotive was meant to operate in the DC environment, how this was achieved might be different because Rivarossi employed more than one designer.

You will need to use an electrical test meter connected to the "red" wheel connection and then go about, touching all metal portions of the locomotive.

With your meter set to Ohms, when you touch the leads to each other, you will get a value of "1", meaning that there is no resistance between the two conductors, a direct connection.

It then becomes a process of elimination. Have the locomotive sitting on a short test track and make a connection to the red rail; in this case, the "red" rail will be the one that is touching the wheels of the locomotive that are insulated from the axle and opposite wheels which rest on the "black" rail.

Then go about touching all metal parts on the locomotive to determine what is conducting "red".

Once you know where these parts are, you can then better determine which parts are conducting "black" by connecting to the black rail and touching the other metal parts.

It's a process which requires slow determination and you may be surprised to discover things that aren't exactly what you expected them to be.

Personally, we would have made the "black" connection to the frame.

If there's an issue about the locomotive operating the in the "wrong" direction, you then swap the motor connections.

Good hunting.

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