Hornby R3676 Mallard A4 – DCC Decoder Install (DCC Ready)
Hornby R3676 Mallard A4 – DCC Decoder Install (DCC Ready)
This article is aimed at beginners or modellers that have just started out with operating their layouts on DCC Digital Command Control. We’ll take a look at installing a DCC decoder into one of Hornby’s recent releases of the popular LNER A4 Mallard steam locomotive model. The Hornby R3676 model is one of Hornby’s super detailed models of the world-famous 4468 Mallard. The R3676 model comes as DCC ready from the factory. What this means, is that the loco as supplied from the factory & is set up to run on traditional DC controlled layouts. However, with it being DCC ready, the model is ready to be converted over to DCC as it’s fitted with a DCC 8 pin decoder socket. The socket has a blanking plug that is plugged into the socket which allows the loco to run on traditional DC-controlled layouts.
To convert it over to DCC (digital command control) is a simple process of unplugging the blanking plug & plugging in a decoder. In this model, the decoder socket is located inside the tender which makes the job of converting to DCC quick & easy job to do. The A4 has been in Hornby’s range for many years & has been retooled a number of times over the years, so depending on which version of the Hornby A4 you have will one of the following:
- No DCC decoder socket (the older tooling) will require the decoder to be hard-wired into the locomotive.
- 8 pin decoder socket located within the locomotive
- 8 pin decoder socket located within the tender
- 21 pin decoder socket located within the tender
See Hornby’s product support download service sheets on Hornby’s website for further details or the supplied service sheet that comes with the locomotive model.
What tools do I need?
A small cross-head screwdriver, a single flat blade screwdriver, Doublesided tape or sticky pad, electrical tape, or Kapton tape. Some form of loco servicing cradle such as the Peco foam servicing cradle. Or soft cloth to protect & hold the loco
What Decoder do I need?
Depending on which loco model version you have, you’ll either need an 8 pin decoder (as in our case here) or a 21 pin decoder.
Do I need a Hornby decoder or can I use other makes of decoder?
You can use any or most makes of decoders with the Hornby A4 locomotive model. Decoders range in price, quality & features, so it’s down to your budget & personal choice as to which decoder to use. My personal choice is mid to higher quality decoders, as I’ve found these give much better smoother running over the budget decoders that I’ve tried out over the years. Plus usually offer more features over the budget decoders. The choice as to which decoder is right for you is down to your needs & budget.
The decoder I’m using is a Zimo 600R 8 pin decoder which has four functions, Railcom & BEMF. This decoder is a high-end mid-range decoder that gives excellent running. Pricewise around the £20 mark. For those that haven’t heard of BEMF, BEMF is kind of like cruise control for an electric motors & helps give smoother running. BEMF stands for Back Electro Motive Force.
Place the loco carefully upside down in the loco servicing cradle making sure that it’s firmly holding the loco & tender. Using a flat-bladed screwdriver, very carefully slide it under the coupling pocket box. Then very carefully prise up the coupling pocket/box up & off the tender chassis. Place the coupling pocket/box to one side.
With the coupling pocket/box removed, access can now be had to the body shell retaining screw.
Unscrew the bodyshell retaining screw & place the screw safely to one side.
Turn the locomotive over the right way up. Then remove the tender body by lifting it up at the rear slightly & then pull backwards away from the tender chassis.
With the tender body shell removed, you’ll now see the DC blanking plug & also a recess in the center for taking a speaker for DCC sound.
Before removing the blanking plug, make a note of which pin/socket is the one that is labelled as number one & make a note of it’s position. We’ve highlighted the number one pin/socket in the photo opposite right. You’ll see a small white triangle with the figure 1 next to it. This denotes which pin/socket is number one.
On the decoder that will be plugged in, on the plug the pin which has the orange wire soldered to it, is the number one pin. So the number one pin with the orange wire goes in the socket that is labelled 1.
Now carefully unplug the blanking plug & place the blanking plug in the locomotive model box for safe keeping.
On the decoder plug, make a note of which pin is number one, the one with the orange wire soldered to it (as highlighted in the photo opposite right).
Now plug in the decoder, making sure that the plug is orientated so that the number one pin goes into the number one socket. As highlighted in the photo opposite right. Press the plug firmly home into the socket. Making sure not to bend or dame the pins on the plug.
Next secure the decoder & make sure the wires are routed safely out of any area that could lead to them being trapped & broken by the refitting of the body shell. Here we’ve used a double-sided sticky pad to hold & secure the decoder. This decoder comes with an insulation sleeve around the decoder itself. Some decoders don’t come with an insulation sleeve, but the model may come supplied with an insulation sleeve for the decoder in the box. If your decoder doesn’t have an insulation sleeve, it’s recommended to fit one over the decoder to help insulate & protect it from short circuits from touching the metal chassis. You can use Kapton tape to cover any exposed metal chassis near the decoder to add further protection to prevent any shorts.
Now test fit the bodyshell to make sure it’ll refit back onto the chassis okay. If the body doesn’t refit properly, check for any wires that may be trapped or the body catching on the decoder.
In our case, I found the part of the tender body shell was catching on the decoder highlighted by the orange circle in the photo opposite right. So the decoder was relocated down into the speaker recess which gave enough clearance for the body shell to refit back on properly. Kapton tape was used to cover the sides of the recess to add further protection against the chassis possible touching the decoder.
Before refitting the tender body shell, the locomotive was placed on the programming track & then using the DCC controller to read back the locomotive address. It should read back the factory default DCC address number 3. Test run the locomotive to make sure all is okay & then place the locomotive back onto the programming track & program the locomotive with DCC loco address you wish to assign to the locomotive. Then get your DCC controller to read back the new locomotive address, if all reads back okay, do another test run. You’ll have to call up the new loco address number you’ve assigned to the locomotive in order to run the locomotive. After test running, refit the tender bodyshell & body shell retaining screw, & then refit the coupling pocket/box.
And that’s it the decoder installation is done.
You can now play about with the decoder CV settings for such things as acceleration, de-acceleration, top speed, lighting effects (if your loco is fitted with lights) & many more settings. Have a play about with the CV settings to suit how your want the locomotive to run. If all goes wrong or not quite how you want it to, you can do a decoder reset by calling up CV8 & writing the value of 8 to CV8. This will reset the decoder back to the factory default settings including the locomotive address back to loco address number three. For many decoders, they either come with a worksheet/information sheet or the worksheet/information can be downloaded from the decoder manufacturer’s websites.
Happy modelling
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