Hornby's Ruston & Hornsby 48DS model is small; its Peckett W4 looks quite large in comparison! If, you hate locomotives stalling, then you may view such a model with apprehension, because any model locomotive with a short wheelbase and few wheels is likely to stall at some point, even with perfect track and a systematic cleaning regime.
Modern technology can rescue us from this situation. A ‘stay alive’ system can help locomotives cope with temporary current collection issues. Also, such a provision makes sound an attractive addition, since continuity of supply will prevent the decoder resetting, or sound breaking up, when dead spots are encountered. While we are about it, wouldn’t it be nice if we could get those front and rear headlights working?
Zimo (MX648F) sound decoder
4 x flat tantalum capacitors
2 x cab lights
Ruston & Hornsby 48DS
Humbrol 113 acrylic paint
Humbrol 33 black enamel
Slater's clear plastic sheet (Plastiglaz)
Stripboard and fibre optic cable
Move the wheels from side to side and check that the pick-ups remain in contact with the back of the wheels at the extremities of movement. On a locomotive like this, with two wheelsets, this is very important.
If the pick-ups are misaligned, use a small flat-bladed screwdriver to release the tab at each corner of the chassis and lift off the baseplate.
Very gently, lift each contact in turn away from the wheel and move outwards using a pair of tweezers. Push the baseplate back into place (orientate it to fit over the gears) and test the loco on DC current.
Once you’re satisfied, detach the locomotive from the match truck. First, gently detach the pick-up wires by holding the two-pin plug using pliers or tweezers and pulling straight back.
Next, pull the coupling bar out from the locomotive using gentle pressure. Both ends of the coupling bar are an NEM push clip-fitting and are designed to be removed.
Remove the buffer beam inserts and/or couplings from the buffer beams by gently levering with a flat-bladed screwdriver for the former, or with your fingers for the latter. Use a container to store all removed parts.
Undo the four screws that hold the body to the chassis; there is one in each corner. Remove the body. You may need to gently hold the catchers out of the way to stop them fouling the pick-up sockets.
To separate the cab/bonnet from the running plate, undo the two screws from below.
Remove the cab roof by lifting from one side with your thumbnail until the glue bonds break.
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Preparing the cab
Create space for wires beneath the control desk using a routing bit in a rotary tool. Wear goggles for all operations using power tools.
Lever out the window glazing. Remove the cab toolbox with pliers, and push out the rearmost two control levers from the reverse with a flat-bladed screwdriver.
Using a narrow cutting disc in a rotary tool, remove the rearmost fittings from the floor of the cab. Protect surrounding areas with masking tape. Swap to a routing tool and remove the toolbox fitting guides from the cab floor.
Using a drill of a diameter to match your fibre optic cable, drill a hole through the centre of each light, through to the inside of the cab.
Stick four tantalum capacitors to a piece of Kapton tape. Make a 'U'-shaped piece of single core wire; we used the legs off the two resistors from the lighting circuit. Solder in place over the positive terminals.
Make a second 'U'-shaped piece of wire to connect the negative terminals. Solder the LifeLink to the corresponding terminals.
Fold the Kapton tape up and bend the LifeLink over to form a compact unit. Test fit the ‘stay alive’ alongside the speaker to ensure that everything fits.
The lighting board is made from a piece of stripboard four holes by five holes in size. Use side cutters to break the gaps between holes and tidy up with a file. Wear a mask and clean up any dust straight away.
Solder two of the resistors supplied with the cab lights into place. Save the resistor legs for the ‘stay alive' build.
Using solid core wire, solder connections to the SMD LEDs (cab lights) and the positive DEC terminal on the LifeLink. Use a multimeter on the diode setting to check the LED polarity.
Solder the lead from the DEC positive terminal to the lighting board. Using the cab as a guide, solder the two cab lights into place, too.
With the lighting board in place, ensure that the LEDs fit directly behind the cab lights and that the roof fits, too. Adjust as necessary. You can file down the solder connections on the circuit board a little for more clearance.
Remove the decoder socket by unsoldering the existing connections. Re-tin the ends of the wires.
Carefully cut the cover from the decoder and unsolder the red, black, orange, grey, brown and green wires. Reverse the direction of the blue, white, yellow, and the two purple wires. Solder the brown wire to the ground pad.
Cover the motor with Kapton tape and mount the decoder using Black Tack. Solder the existing pick-up and motor wires in place, consulting the decoder documentation to check the position. Disconnect the speaker purple wires at the speaker end.
Temporarily refit the running plate over the chassis. Use tweezers to help the sandbox pipes over the wheels. Hold the cab in place for the next step.
Run the wires through to the cab and cut them to the correct length, making allowance for bending around contours. Strip the ends of the wire and tin them ready for soldering.
Take the chassis out and re-attach the cab and bonnet to the running plate. Thread the wires back through to the cab. The bonnet hooks under the buffer beam. Refit the chassis screws.
he speaker is fixed upright in the rear of the cab using a small blob of cyanoacrylate underneath. Solder the two purple wires to the speaker terminals. Glue the central cab level back into place.
Slide the lighting rig into place – it shouldn’t need gluing. Solder the blue positive wire to the DEC positive (+) terminal and the brown wire from the decoder ground to the LifeLink DEC negative (-) connection.
The white and yellow wires go to the lighting circuit board. Use Black Tack to hold all wires in place against the surfaces they pass over and to hide them from view.
Double check all your wiring. Now test the locomotive on a programming track and ensure that you can interrogate the decoder address. If okay, then proceed to run it as normal.
Put Black-Tack around the LEDs in the cab to stop light leakage. Using an old brush, paint the inside of the cab with Humbrol 113 acrylic paint and leave alone until it is dry, then retest the locomotive.
Cut a short length of fibre optic cable and glue into place using PVA, then paint the part in view in the gap between the cab and the light fitting with black enamel paint to prevent light leakage.
Make new glazing from Slater's clear sheet using the old ones as templates. Cut and file to shape and hold in place with Clearfix. Glue the cab roof back on with cyanoacrylate. And that's it - job complete!
For more information on DCC controllers, have a look at our guide here.
If you're looking for more advice on wiring your layout, the below articles should help give you a steer.
Wiring your model railway - top tips
How to fit a DCC uncoupler
Still searching for trackplan inspiration? Our guide gives you simple trackplan suggestions to help you get started.
If you’d like some more advice, take a look at the BRM Techniques page for all our latest guides and advice articles.