There are four posts on the Marx 1249 transformer, but don’t fret if you’ve lost the instructions. Connecting it is easy. But first, you’ll probably want to check it out for safety before plugging it in.
There are two sets of posts on the transformer, but don’t let that confuse you. One set of posts powers the train, and the other set powers any accessories you might have, such as a station. If you don’t have any accessories, you can simply ignore the second set.
The Marx 1249 transformer overview
The Marx 1249 is a 50-watt transformer, enough to power the train it came with and one or two accessories. It does have a circuit breaker for safety and the separate sets of posts for a train and accessories puts it a step above the transformers that Marx supplied in its cheapest sets. It’s an adequate transformer for a small layout.
Connecting the lockon and wires to the track
The lockon is a black piece of fiberboard with a connector for a rail on one end, a connector for another rail in the center, and a connector for two wires on the end.
The first step is connecting the lockon to the track. The lockon connects to the center rail and one of the outer rails. Original Marx lockons poke into the grooves in the underside of the track, perhaps to avoid infringing on Lionel’s patents. If you’ve lost the original lockon, a Lionel lockon works fine.
If you have more than one lockon, you can use them both. Put them on opposite sides of your loop of track.
You’ll also need two pieces of wire per lockon. I recommend no less than 18-gauge wire. If you’re going to use more than one lockon I recommend you either color-code them or mark them with tape to keep them straight. If you only use one lockon, it doesn’t matter which wire goes to which connector on the lockon.
Connecting wires to the track without a lockon
If you’ve lost the lockon and don’t want to pay $4 for a new one, or don’t want to use one, buy a package of spade terminals, crimp one to one end of each of your two wires, then spread the groove in the underside of the center rail and one outer rail slightly with a slotted screwdriver and press the spade in. Once the spade is inserted into the track, bend the terminal to the side so that the track can sit flat.
Or if you don’t mind soldering, solder the wires for a super-solid connection.
You can connect more than one set of wires if you like. And if you use more than about 10 pieces of track, total, you’ll benefit from a second connection. Be sure to mark which wires go to the outer rail and which ones go to the center rail.
Connecting the Marx 1249 transformer to the wires
There are four posts on the transformer themselves. One pair is labeled “To track, 7-13 volts.” The other is labeled “Accessories, 13 volts.” The track wires go to the pair of posts labeled “To track, 7-13 volts.”
The train will run no matter which post you wire to which rail, but it’s a good practice to wire the top post to the outer rail, and the lower post to the center rail. If you use more than one lockon to keep your train’s speed consistent, consistency in wiring is critical.
To make the wires easier to connect to the transformer terminals, twist the ends of the wire together, then loop the end into a J-shape. Loosen the nut on the transformer post. Loop the wire over the post, squeeze the loop closed, then tighten the nut back down. Repeat for the other wire, and that’s it for the track.
The other set of posts powers accessories. Here’s the secret of wiring Marx accessories. There are lots of shortcuts you can take that will save you time and effort and maybe even some wire.
If you’re just using a single transformer and a single loop of track, that’s it. Enjoy running your train.
If you want to run more than one transformer with blocks of track, things get a bit more complicated. Be sure to follow my instructions for phasing transformers.