Battery Power MU Plug - USA Trains F3-A

by Paul Norton

INTRODUCTION

Aristo-Craft, Plug and Play diesels are sold with MU plugs on each end. This project shows how to add the same plug to a USA Trains F-3A so you can use a power car to run it. While this project deals with a specific locomotive, the principles are the same for other USA Trains, four axle diesels.

Nothing in this project prevents this locomotive from being restored to track power for re-sale at a later date. As the locomotive’s track power wiring will be unplugged during this project however, a power car will be required to run it. A power car is simply a battery car with a receiver added for on-board, radio control. To view an article on how to build a Power Car, just click on the link.

Two, 2-pin plug sets are required for this project. They are available from All Electronics under part number CON-240 for $1.35 each.

REMOVING THE TRACK POWER SLIDERS

Place the locomotive upside down in a soft cradle taking care not to damage the horns. Place a piece of foam or pieces of cardboard between the top of the motor blocks and the frame. This prevents the motors blocks from dropping and dislodging the axles when the bottom covers are removed. Remove the six screws (circled in red) from the bottom of each motor block and remove the bottom covers.

Remove the small screw (circled in red) from each track slider bracket. Lift out the track sliders and the pieces of piano wire (indicated with yellow arrows) sprung between the axles.

The track sliders and axle wipers are the only components removed during this project. Place them in a baggy. Mark the road name, diesel type and unit number on the baggy and tape it in a pocket of the locomotive’s Styrofoam packaging.

Fasten the track slider brackets back in place. Fasten the covers back on the bottom of the motor blocks. Remove the foam or cardboard from under the motor blocks.

REMOVING THE F-3A SHELL

Remove the two screws from the base of the coupler mounting brackets and remove the couplers. Put the screws back in the frame so they do not get lost.

Undo the two screws at the base of the fuel tank. Lift the fuel tank off and set it aside for now. Put the screws back in the frame.

There are nine screws holding the shell to the frame. These are hidden in deep burrows in the frame and will require a long Phillips #1 screwdriver to remove them. It is not necessary to remove the motor blocks in order to access these screws, however the first screw hidden under the front motor block is difficult to get at.

Gently spread the front of one of the side frames with one hand and push the motor block the other way with the other. Lift one the axle end out of it its bushing and set it on top of its journal. Repeat the process for the other end of the axle. The front of the motor block can swung up and the first screw removed. Replace the axle back in the side frames when done.

The next two screws are under the side frames at the back of the front truck.
Four are in the fuel tank area.
The last two are under the side frames at the back of the rear truck.

Place a forefinger in the hole in the center of the frame and GENTLY pull down. The frame should bow SLIGHTLY. Push down on the front pilot anti-climber and the front of the shell should pop free of the frame. Pull the frame forward and the back of the shell should pop free. Lift the shell up, but just far enough to lay it beside the frame.

Identify the 2-pin and 3-pin connectors on the power distribution board for the front lights.

Unplug the connectors and set the shell aside.

INSTALLING THE MU PLUG

Undo the twist ties that group the locomotive wiring together.

There should be two plugs from the front motor block, but only one plug has two red wires and two black wires on one side of it. It is attached to the power distribution board at PICK1 and is for the front truck, track power pick-ups. Undo it to isolate the front truck, track power pick-ups.

There should be two plugs from the rear motor block, but only one plug has two red wires and two black wires attached on one side of it. It is attached to the power distribution board at PICK2 and is for the rear truck, track power pick-ups. Undo this plug to isolate the rear truck, track power pick-ups.

Drill a 1/8 inch hole in the center of the frame, 5/8 of an inch from the back.

CAUTION: The 2-pin plug sets sold by All Electronics, hereafter referred to as AE plug sets, are not always colour coded the same as those in USA Trains locomotives. If the AE plug sets are not the same, just click on the following link to see how to switch the MU plug wiring so that proper polarity is maintained.

As only the male halves (indicated with red arrows) of the All Electronics plug sets are needed for this project, unplug the females halves and set them aside. They can be used later for power cars and other projects. Hereafter the male halves of the sets will be referred to as the AE plug.

Cut a two inch length of shrink-wrap tubing. Slip it over both wires of an AE plug. With the tab of the plug facing up, slip the wires through the hole in the bottom of the frame until the shrink-wrap is snug against the frame and the AE plug. Apply hot glue over the wires frame on top of the frame for stress relief.

Insert the other AE plug into the open plug attached to the power distribution board at PICK2.

Gather the ends of the wires of this AE plug and the AE plug installed on the rear of the locomotive. Trim the wires to length and strip 1/4 inch of insulation off all four wires. Slip a 3/4 inch length of shrink wrap over one of the red wires, and over one of the black wires. Solder the red wires together. Slip the shrink wrap down over the joint and warm until it seals. Repeat for the black wire.

THAT’S IT! You have completed the installation of an MU plug on your USA Trains F-3A. All that’s left to do is test to ensure the it is wired correctly.

TESTING THE MU PLUG

Plug the lights back in to the power distribution board and set the shell back on the frame. Ensure all wires are inside the mounting posts so they do not get pinched between shell and the lip of the frame

Connect a power car to the MU plug. If a power car is not available, connect the female portion of an All Electronics plug set to a small power pack for testing. Test to ensure the motors and lights are operating properly.

If the motors and lights are not operating properly, check the colour coding of the wires of the AE plugs to ensure they line up with the USA Trains plug.

Once the MU has been tested; fasten the shell, fuel tank and couplers to the frame.

CONGRATULATIONS! The MU plug will allow you to run your F-3A locomotive with a trailing power car and enjoy all the benefits of battery power and radio control.

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Last Modified 8/25/08 3:40 PM