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Which F-7A?

LGB is beginning to provide their MTS decoder as standard equipment. They appear to be doing this by road name. The earlier released F-7A's do not have an MTS decoder. If you F-7A has an MTS decoder, you may disregard this write-up. However, if you need to know about programming the MTS, see the programming instructions in the DCC in the Garden section.

Easy Install

For this installation, I took the easy way out. I left the lighting up LGB. It now stays on all the time when powered by DCC. The only thing the decoder controls is the motor.

Heat Tolerant / Running on DC

When the temperature gets close to 100 degrees here in Texas, the locomotive electronics stop working. Therefore, this locomotive installation contains a switch which puts the locomotive back on DC. You can then either run the locomotive on address 0 or power the track from a DC power pack. The later defeats the elegance of running on a wireless throttle, but is a practical means to participating in shows during the summer.


LGB has a B-unit that contains sound. You can also install a sound unit into the F-7A if you want to save yourself some money. The extra green and blue wires leading off the bottom of the schematic are for this purpose. The green wires are for powering the sound unit. The blue wires are for sound units that detect power going to the motor to activate the chuff as well as operate the bell and whistle. The circuit for a Soundtraxx Sierra is shown in the G Generic Sound write-up.

Twisted Wiring / Forward Running

For perhaps compatability with other LGB locomotives, the connector from the powered trucks both have a twist in them. All four wires from each truck were twisted. In the schematic, I only show two of the wires twisted from the rear truck. By swapping the wiring, the LGB locomotive will now follow the standard running convention of locomotives in smaller scales - that is, when a positive voltage is applied to the right rail, the locomotive runs forward. LGB locomotives typically run backward under these conditions.


Installation is simple. The switch was mounted in the floor above and a little forward of the rear truck. The decoder was also mounted above the left truck. While it doesn't really matter, the front truck is the left one shown in the schematic and the rear is the one shown on the right.


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