Spectrum 1:20.3 Scale 2-6-0 DCC install

[RGS man]

DCC installation in the Spectrum owners manual is insufficient.  Do you have a wiring diagram for the Digitrax DG583Sm, G Scale DCC mobile decoder?  I've printed the wiring connections for subject 2-6-0 Mogul, but it is not color coded.  Please let me know which wires need to be re-routed from the Spectrum G814X-PCB01 and connected to the Digitrax DCC decoder.

Thanks,
RGS Man

[Kevin Strong]

Your best bet will be simply to bypass the on-board PC board and wire the track power and motor to the decoder itself. The wiring in the 2-6-0 is not all that difficult. You've got wires coming from the rails, with track pick-ups on the loco and in the tender. That feeds the PC board, which controls the smoke, headlight, firebox lights, cab lights, and tender light (if your loco has one.) The track pick-up and motor leads are easy to trace. If you're installing the Digitrax decoder in the tender, there are two screws holding a bunch of brass tabs together. Just tap into that for the track power.

If you're installing the decoder in the locomotive, then just trace the wires coming from the wheels to the PC board. While you're looking at the PC board, find where the motor plugs in and unplug it. Wire the motor directly to the Digitrax board's motor output. There's a noise filter attached to the back of the motor. You may or may not opt to remove that. Removing it has been known to improve how things work on some control systems, but I don't know that I'd deem it imperative.

The headlight should also just plug into the PC board. You have an option here. You can leave it plugged into the PC board, and it will be constantly lit so long as there's power on the track. Personally, I'd cut the leads and wire it directly to the Digitrax board so you can turn it on and off as needed. Wire it to the decoder as you would any LED; just make sure you use a suitable dropping resistor in the circuit. There may or may not be one already wired in with the headlight; look for a small length of heat-shrink tubing at or near the light itself on one of the leads covering a small bumpy cylindrical thing about 3/8" long. If you don't see that, then you don't have a dropping resistor in line with the LED and you must add one. I usually use a 1000-ohm resistor. If you're using track voltages nearer to 24 volts, you may want to use a 1500-ohm resistor.

If your loco has a back-up light on the tender, you will want to wire that to the decoder. Because DCC is AC (bi-polar square wave), if the tender light is run off of track power, it (like the headlight) will always be illuminated. If your tender doesn't have a light, then don't sweat it.

The firebox and cab lights you can leave hooked directly to track power. They'll be on so long as there's power to the track, but you're not going to hurt anything. (That, and if a steamer is ready to go, there's got to be a fire in the firebox.)

Depending on where you mount the decoder, you may be able to get away with using the 6 wires running between the loco and tender. Stock, the 4-wire connector carries track power forward and (if equipped) power to the tender light. The 2-wire connector on the opposite side carries the chuff trigger (rear axle) back to the tender.

If you do not have a back-up light, you can use the second pair of wires on the 4-wire connector for power to the motor. Depending on whether you control the headlight from the Digitrax decoder (you control) or PC board (always on), you could use the 2-wire connector to control the light. You sacrifice the chuff trigger, but since you don't mention sound, that may not be an issue. If you wish to retain the chuff and control of the headlight and mount things in the tender, then you'll have to add 2 wires running between loco and tender.

Hope that helps.

Later,

K