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HORNBY’S 28XX (Model R2153B) Conversion to DCC

April 2013

 

  In 2007 I converted my 00 layout to DCC and in the process of culling my collection of locos and chipping those that I wish to keep, the above loco which has a glowing firebox and a smoke unit which appear, could be converted to DCC with a bit of work.

In the box with the loco is the leaflet on maintenance and a small sheet on Instructions for Locomotive Smoke Unit. The leaflet and small sheet did not show the Firebox unit or the smoke unit, so I obtained Service Sheet No.277B from Hornby’s Website.

First I tackled the tender and after lifting off the body, I found all the wiring was done with black wire so  I did one side at a time so as not to mix up the wires, de-soldered the wires from the power collectors and the resistor and replaced those wires with a single wire of a different colour  connecting the fore and aft collectors on each side. As each single wire was soldered I then soldered the feed wire from the drawbar collector to the appropriate brush arm.  I then re-soldered the black wire from the front collector so that it pointed downward and threaded it through the gap immediately behind the drawbar top connector. I then tested that the motor was isolated and each of the wheels on the side had continuity with the appropriate lead now coming out in front which would connect with corresponding driving wheels of the locomotive.

Below are some photos of the conversion project, starting with side and front views of original wiring followed by the new rewired system. Next is the connection between loco and tender, then of the NCE D13SR decoder with the green wire added for function 3. The final photo is of the decoder wires attached to the appropriate connections for motor, track, fire glow box and smoke unit with heat shrink pieces ready to cover the joining wires.

 

 

 

 

 

 

 

 

 

 

 

 

 

     

                                   The original Hornby wiring - every single wire is black in colour,  Side. view and front end view.

 

 

 

 

 

 

 

 

 

 

 

 

 

                New wiring connecting front and rear pickups and showing the front end of tender with the wires to attach to the locomotive pickups.

 

Tender  re-assembled with pickup wires ready for connection to locomotive.

 

Now onto the locomotive; - I first had to find out how much current draw the smoke unit would take when in operation. Luckily at the last club meeting at the end of March 2013 there was an ammeter amongst the items that the layout owner wanted to divest as he was dismantling his layout. This item was put in my pile to take away.  The ammeter was installed in my test circuit and showed the readings obtained for the combination of Firebox glow unit and Smoke unit and then individual units as shown below.

 

 

 

 

 

 

 

    

 

 

 

 

 

   1.  Firebox and Smoke unit combined drawing 175-180mA at 12volts DC.                           2.  Reading of combined units at 6- 8volts DC was 165mA.

 

 

 

 

 

 

 

 

 

 

 

 

     

      3.   Firebox Glow unit draws only .020mA.                                                                                           4.   Just the Smoke unit drawing 155mA

    I then placed the locomotive with the tender connected upside down in a cradle and soldered the wires to the tabs on the end of the loco's chassis.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Next I chose a NCE D13SR decoder as it is a 4 function 1.3amp which is bigger and more suitable than the Hornby R8249. The D13SR fits snuggly in the Belpaire firebox and therefore easy and nicely placed to connect to the wiring circuits of the motor, firebox glow and smoke units. Note: - there is not much room to place any decoder in the tender as the motor takes almost all the space of the 3500gal tender body.  When looking at the chassis where the wires from the 8 driving wheels collectors are attached, I found that they were soldered onto tabs which made easy to solder the wires from the tender wheels, therefore the loco and tender had to be permanently attached.  I tested that each side had continuity and then proceeded to the smoke unit and glow box.  The pair of wires soldered to the glow unit and smoke unit were unsoldered and separated-one set is from the wheel collectors and the other is to the motor contacts of the draw bar- therefore the right point to attach the decoder.

 

 

 

 

 

 

 

 

 

 

 

 

 

I soldered the Orange, Red, Black and Grey  decoder leads to the correct wires, then the White and Yellow joint to the left hand feed of the smoke unit after cutting it off the probe, the Blue to the right hand original contact solder of the glow and smoke units and finally the Green to the glow unit’s left contact. Note;- the left hand probe of the smoke unit is inserted to steady the wire to the glow unit’s bulb. Now the locomotive was ready for testing and if successful the decoder would be located on top of the firebox and the length of the wires trimmed, joins are covered by heat-shrink and loco body re-assembled and track tested.

 I hope to show a video clip of the loco in action soon when I get a chance to shoot it.