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Fitting DCC Sound Decoder & Speaker Into A Bachmann Class 66

Fitting DCC Sound Decoder & Speaker Into A Bachmann Class 66

FITTING A DCC SOUND DECODER

 

In this article we’ll take a look at fitting a DCC Sound Decoder & speaker into a Bachmann Class 66 model. The model i’ve chosen for this article is the Bachmann 32-979 Class 66 – 66412  in Malcolm Rail / DRS  livery. This model comes as 21 pin DCC ready model.

Model as supplied from the factory runs on tradition analogue control. It has a 21 pin DCC decoder socket with a blanking plug in the decoder socket, which allows the model to run on non DCC layouts. To convert to DCC remove the blanking plug & plug a DCC decoder into the decoder socket. It’ll then run on DCC controlled layouts.

Sound decoders range in various prices from Hornby’s Budget TTS sound decoders up to the likes of those by Legoman Biffo, Digitrains, Howes, Southwest Digital, YouChoos & many more. The sound decoders usually come supplied with a speaker these are either already soldered on to the DCC Sound Decoder or separate speaker for soldering on to the decoder or the loco model PCB board.

The sound decoders have sound files installed on them, & usually have an instruction sheet giving info about what all the sound functions do, C.V. settings, sound volume settings etc. A lot of sound decoders have around 29 functions an example list of functions is  shown here for a diesel model:

Typical Function list for a diesel model

F0     Headlight/rearlight (if fitted to locomotive)
F1     Engine start/stop
F2     Horn high-low
F3     Horn low-high
F4     Brake squeal
F5     NOTCH up
F6     NOTCH down
F7     Return to IDLE
F8     Thrash
F9     Cold start override
F10   Compressor
F11   Door slam
F12   Fan
F13   Horn high
F14   Horn low
F15   Primer
F16   Slow flange squeal
F17   Spirax valve
F18   Horn short low
F19   Horn short high
F20   Wagons buffering
F21   Wagons clanging
F22   Coupling
F23   Dispatch whistle
F24   Buffering
F25   Aux (if used in locomotive)

Depending on what speaker you use effects the quality of sound so it’s worth upgrading the speaker from the standard one that comes supplied with the sound decoder. The likes of Bass Reflex speakers are recommended as these get the best out of the sounds. Other speakers worth looking at are the ‘Earth Mover’ by Leggoman Biffo, & Zimo 3D range of single / twin speakers. A number of modellers are also fitting the likes of i-Phone speakers into their models too! If your model is tight on space for a speaker it’s worth looking at one of the sugar cube type speakers.

Before buying an upgrade speaker make sure you check that your chosen speaker is suitably rated for the sound decoder. The DCC sound decoder retailer will be able to advise you this. Below can be seen a few examples of the different type of speakers mentioned above.

 

A bass reflex speaker
A Earth Mover speaker by Legoman Biffo
A Zimo 3D Twin speaker
Zimo 3D Sugar Cube speakers

Fitting the decoder & Speaker

Tools You’ll need are…

  • Posi-drive Screwdriver
  • Four pieces of card or Plasticard
  • Wire Cutter / Wire Stripper Tool
  • Soldering Iron
  • Optional: Peco Loco Servicing Cradle

 

First test run the loco & run in for an hour on traditional DC control. Place the loco upside down in the Peco Servicing Cradle (or just use a soft cloth instead). Unscrew the four screws that hold the body on. These are located either side of the fuel tanks below the inner ends of the bogies. I’ve circled the screw locating holes as seen on the right.

 

Having removed the four screws carefully ease the body lower sides away from the chassis. Insert four pieces of card or Plasticard between the body side & chassis near the cab sides. The body has four clips located around the cab sides area & one clip at each end located under the cab fronts. Now carefully ease the body away from the chassis taking care not to knock or break off any detail bits!

 

 

Having removed the four screws carefully ease the body lower sides away from the chassis. Insert four pieces of card or Plasticard between the body side & chassis near the cab sides. The body has four clips located around the cab sides area & one clip at each end located under the cab fronts. Now carefully ease the body away from the chassis taking care not to knock or break off any detail bits!

 

 

With the body removed we can now access the DCC socket. In the photo on the right you can see circled in orange a Bachmann 21 pin decoder that i had already plugged in previously. Circled is where you’ll find the blanking plug. Unplug the blanking plug by lifting it upwards off the socket pins as seen on the right. Place the blanking plug in the model box for safe keeping.

 

 

For the sound decoder for this model I’ve chosen a Leggoman Biffo class 66 sound decoder ( ESU Loksound ). The standard speaker is also supplied with the decoder in the box. The speaker seen on the right is a Bass Reflex one bought separately to the sound decoder.

 

 

Bachmann have included space for a speaker as can be seen on the right. The roof on the body that sits over this section of the chassis has holes behind the vents to allow the sound to escape the body.

With this speaker i found it was a tiny bit too long & was pushing the back of the cab interior forward. This interfered with the refitting of the loco body. So a smaller twin bass speaker by Zimo as seen in the second photo on the right has been used instead.

(Note: The Bass reflex speaker can be positioned in the loco fuel tank area but this does mean some cutting of the full tanks is needed.)

 

 

Next fit the wires to the speaker & have used some 16.2/o wire. The Zimo speaker has sprung tabs that the wires can be simply pushed & held in place by the tabs. However it’s best to solder the wires on to the tabs as shown on the right, doesn’t matter which way round the red & black wires go on the speaker.

 

 

We now turn our attention to the PCB circuit board on the loco. You’ll see in the photo on the right two tabs marked SP+ & SP- these are the speaker connections.

  • The red wire goes to SP+
  • The black wire goes to SP-

Solder the two wires to the tabs as shown in the photo. However if you don’t do soldering  you can push the wires through the holes on the tabs & hold in place with a black sleeve instead. You’ll see a black tab sleeve to the left in the photo, contact Bachmann service / spares department via this link http://service.bachmann.co.uk/ to purchase spare PCB board black tab sleeves.

 

 

Now fit the sound decoder as shown on the right by pushing the decoder down on to the pins. Take care not to bend any pins whilst plugging in the decoder.

 

 

Now place the speaker in the space as shown in the photo on the right. Use the likes Black Tack, Blue Tack, Tacky Wax or tape to hole the speaker in place. Make sure that the wires from the speaker to the PCB board don’t foul moving parts or get in the way of refitting the body.

 

 

Refit & re-screw the body back into place.

 

 

Having checked that the body is back on ok place the loco on to your DCC programming track. Set the DCC controller to read back the loco address. It should come back with the factory default address of 3. Place the loco on your layout & test run to make sure all is ok. To start the loco engine sounds press function button F1. Once started up away up go the first test run with sound. Once your happy all is okay then place the loco onto your programing track & assign an new loco address nuber of your choice.

Sound Volume

If the volume of the sound is too high or too low you can turn the sound up or down. To do this place the loco on to the programming track.

  • Select CV Read & call up CV63
  • Read what CV63 reads back as & make a note of that number
  • Select CV write & call up CV63

 

  • To turn sound down
  • Select CV write & call up CV63
  • Pick a number lower than what CV63 read back at & type that in & hit confirm
  • Test run with sound on. Repeat  reprogramming CV63 until happy with volume of sound
  • To turn sound up
  • Select CV write & call up CV63
  • Pick a number higher than what CV63 read back at & type that in & hit confirm
  • Test run with sound on. Repeat reprogramming CV63 until happy with volume of sound

If you mess it up you can do a decoder reset which puts the decoder back to as you first bought it. To reset call up CV8 & select 8 & hit confirm. This will set the decoder & as well as resetting the loco address back to number 3.

In this video will give you some idea of the different sounds & functions (Skip to around 1:59 into the video) https://www.youtube.com/watch?v=unMXd7eBx0Y

 

 

Happy modelling

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2 Comments

  1. PACtrain

    Great instructions – very useful. How about using a few strips of thin but relatively strong plastic from a yoghurt pot.

    • Iain

      Your welcome 🙂 That’s a great idea using the yoghurt pot plastic for helping to remove the body.

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