Installing DCC into the USA Trains GP30

Introduction

USA Trains of Malden, Massachusetts, USA (a North-Western suburb of Boston MA) are one of a small number of companies manufacturing G-scale models. They produce a range of 1:29 scale models of standard gauge equipment for operating on 45mm track, primarily intended for use on Garden Railways. Late in 2002 they released a new model of the GP30 road/switcher locomotive. The GP30 was a product of the General Motors Electro-Motive Division (EMD) and was one of the earlier and smaller examples of what would now be considered a typical road/switcher diesel locomotive. It's available in a wide range of road names and running numbers and looks very good indeed. It has two powered twin-axle trucks, and includes numerous lights and operating smoke.

This page covers my experiences attempting to fit a DCC decoder inside this model. This is a pretty difficult locomotive to modify; I certainly found the process long and frustrating. In particular, although the external detail parts are reasonably solid, fitting DCC requires digging deep into the inside of the locomotive where the detail parts are nowhere near as rugged. I broke a number of them off while performing the modification, and while I'll attempt to warn you of the pitfalls in this document, I think it would be unwise to assume you'll be able to do it entirely without breakage. The decoder I choose to fit to this locomotive was a Lenz LE4024B decoder which features screw terminals, a 4-amp current rating and four function outputs. Time will tell whether this will be sufficent, but from what I've read and test results with a ammeter equiped power supply, I'd say four amps is an absolute minimum value for this locomotive.

You will need the following tools to perform the modification (at a minimum):

• a smallish Philips screwdriver with a long handle
• a pair of thin-nosed pliers
• a pair of wire cutters
• a very sharp knife
• a soldering iron with a fine tip
• a multimeter.
• a DC transformer capable of being set to both low voltages (around 5V) and higher (around 12V) for testing components independantly.

• Suitable Heavy Duty (Large Scale) DCC mobile decoder with screw terminals - the one used in the illustrations is the Lenz LE4024B decoder. Those by other makes such as Digitrax should also work just fine. Since LGB do not recommend it's solitary use on their own locomotives with two motor blocks, it would probably be advisable not to use their 55021 decoder with this locomotive, at least as described.
• Fine-grade electrical solder
• Plastic insulating tape
• 6 24volt minature light bulbs - I used LGB part no 68513 (Plug-in bulb, clear, 24V)
• 6 sets of battery connectors - I used Aristocraft part no ART-29511 battery leads which contain a pair of connectors, one female, one male, each on a short length of wire.

What Type Of Modification You Want To Do

For some reason, despite the fact it's a very recent design, USA Trains appear to have given no thought at all to the use of DCC with this model. In some of the more frustrating moments, I even wondered if they'd deliberately made it difficult in order to promote sales of their competing Scale Command system, a promotional video for which is included with the locomotive. The simple truth is, this is a tough locomotive to modify, at least if you want to get the most out of it. Much of this is due to how the lights on the locomotive work. You have basically three possible courses of action:

1. Just install DCC for motor control and leave the lights to act only when the locomotive is moving as they do with DC operation. This is reasonably easy to do given the right parts, is reversable and should be quite quick.
2. Replace and re-wire the headlights at both ends, and the cab lights to bring them under DCC control, but do not do anything about the directional running lights, leaving those to operate as they do in DC operation. This is the option detailed here.
3. Re-wire all lights to work under DCC control - this requires replacing all eight light bulbs and 4 LEDs, the LEDs with a specialist part that is hard to obtain. An alternative to this is to fit a rectifier, regulator and relay circuit to provide suitable power to the existing LEDs.