Large Scale Central

RCS fits new battery R/C to a USAT GP38-2

I recently had the opportunity to fit a new RCS R/C system and Fosworks COBRA-260 ESC to a latest run USAT GP38-2.
Knowing that USAT diesels have in the past been very susceptible to gear failure I very carefully checked out this example.
All the axles were perfect.

This particular installation was to be fitted with a Centre OFF 100 Watt COBRA-260 ESC. These are virtually identical to my new Low OFF RCS # OMEGA-10 100 Watt ESC.
The owner wanted to use one Tx hand-piece to be able to control 1 x battery R/C loco and 1 x TITAN track-side R/C separately from the same hand-piece. The EVO-DUO+ hand-piece can do this and also provide 4 x sound trigger functions for the diesel.

The GP38-2 was ripe for some creative internal layout of components.

I started with the MyLocosound, Speaker and MRW-SSQS quad R/C sound trigger by mounting all of them in the fuel tank.
The Infra Red sensor for programming was mounted up under the frame of the loco. Top left in pic below.
The wires were neatly bundled together and fed up into the loco body for connection to the control panel on top of the loco.

The 2,600 mah 5s Li-Ion battery pack was mounted between the stanchions on 10 mm square styrene tubing glued in place with silicone adhesive and secured to the loco frame by a cable tie.
I never re-wire USAT locos. Instead I leave the stock wiring in place and feed the motors direct from the ESC. I power the loco electronics by the traction batteries fed via a DPDT relay which is controlled by the directional lighting outputs of ESC lighting outputs. The relay is mounted on the battery pack for convenience.

The result is constant brightness directional lights and the two marker lamps change colour with direction change.

Whilst working on the loco body removing the two smoke units (they eat batteries) I discovered that the top centre section of the loco body could be made removable. It is held in place by 4 x screws which are easily removable.

Once the top cover was removed making a control panel to hold switch, charge jack, Rx and ESC was easy peasy.

The dimensions are here:

The DSM2 Rx was mounted on the top side of the panel. The servo leads to the ESC and quad R/C sound trigger pcb in the fuel tank come up through a slot in the panel.

The COBRA-260 was mounted on the underside of the panel.

In hind-site that was not a good idea. The minute amount of radiation from the ESC interfered with the Rx because it was too close to the antenna. The thickness of the styrene is not enough, although only an inch or so separation is actually needed. After testing I replaced the Rx with a Deltang Rx with a long range antenna the receiving part of which was well away from the ESC.

The panel is supported by 5 mm square styrene tubing glued to the insides of the loco body. The panel sits on top of the tubing and secured in place with 2 x spare USAT body mounting screws.
I glued some small pieces of styrene tubing in the old screw holes to act as guide pegs when removing and replacing the body cover.
The result is no holes drilled into the loco at all.

It runs really well on the 4s (14.8 volt) pack although a 5s (18.5 volts) pack would give a higher top speed which many users would prefer.
Range is about 200’ and duration around 2 hours with a 10 car train on a flat layout.