DCC Fitting Guides – Bachmann Class 04 Diesel Shunter (Non DCC Ready Version)
DCC Fitting Guide – Bachmann Class 04 Shunter (Non-DCC Ready Split Chassis)
For this article, we’ll take a look at converting a Bachmann split chassis locomotive model from analogue to DCC. The Bachmann class 04 model has been around since the late 1990’s with the earlier versions being analogue, means that any conversion of the model to DCC will have to be hard-wired. Extra care will need to be taken when converting this model due to to it being a split chassis, with the two halves of the chassis being electrically isolated from each other. You will need a small decoder for this project, for example, the likes of a Gaugemaster DCC22 Micro Decoder or Zimo MX617R Micro decoder, being two examples.
Tools required are wire cutters/wire strippers, soldering iron, solder & flux, Screwdriver (for body removal), Kapton Tape, heat shrink. It’s a good idea to have a small tub or tray to store the loco body screws so you don’t loose them. We’d like to also thank Chris Bower for his help & assistance on this conversion for this article.
Let’s Get Started
Before conversion to DCC takes place, the loco was checked & test run on traditional DC to make sure all is running okay. Happy that the loco was running okay, we then proceeded to start the conversion in the following steps below. For this conversion, we’re using a Zimo MX617R Micro decoder & possibly also fitting a stay alive unit again from Zimo, part number SACC16. DCC technology is moving at a rapid pace & it’s intersting to note that the decoder has 8 functions which is impressive for such a small decoder.
Body Removal
To remove the body, unscrew the screw under the cab end of the locomotive, as highlighted in the photo opposite right.
Now unscrew the screw under the nose front end of the locomotive, as highlighted in the photo opposite right.
The body can now be lifted clear of the chassis. When removing the body, be careful not to lose or damage the sand pipes.
Next, turn the loco chassis upside down & unscrew & remove the two screws that hold the bottom chassis plate. With the screws removed, lift off the bottom chassis plate section. This will now expose the wheel axles.
Now swing the wheel/axle assembly away from the chassis as shown in the photo opposite right.
The two screws that hold the conrod gear & rear counterweight need to be unscrewed to release the conrods & wheels from the chassis. The screws are located on each side of the chassis within the rear counterweight.
The two screws that hold the conrod gear & rear counterweight need to be unscrewed to release the conrods & wheels from the chassis. The screws are located on each side of the chassis within the rear counterweight.
Opening Up The Chassis
With the body & wheelsets/conrods removed, we now need to get the split chassis opened up. This is an easy task to do, simply unscrew the three screws that hold the split chassis together. The photo right shows the location of the three screws that need to be removed to open up the chassis.
With the chassis now unscrewed, it can be finally opened up. In the photo opposite right can be seen two highlighted plastic insulation dividers. These two plastic insulation dividers, keep both sides of the chassis electrically isolated from each other. Make sure you note where these both fit & located within the chassis, put the two plastic insulation dividers safely to one side.
The motor can now be released from the chassis by simply lifting it out. The two contacts we’ll be connecting from the decoder & soldering on to, on the motor, are highlighted in the photo opposite.
One thing to note is that the motor has two removable plastic insulating sleeves either side of it. With the model having a split chassis, the plastic insulating sleeves are required to insulate the motor from the chassis & thus prevent an electrical short. When the model is reassembled, the plastic insulating sleeves must also be refitted.
Hard Wiring The Decoder
The decoder will need to be one with a wired pin plug type. As mentioned we’re using a Zimo Micro MX716R eight-pin decoder. The first job is to cut the pin plug off as shown in the photo opposite right. Cut as close to the pin plug to maximise the length of the decoder wires.
As the Bachmann class, 04 shunter has no lights fitted, we don’t need to use some of the decoder function wires. The function wires that we won’t be using, are cut close to the decoder & removed as follows. Cut & remove the blue wire.
Next cut & remove the yellow wire, & also cut & remove the white wire.
Unless you have a spare decoder wire in your toolbox, keep the yellow, blue, white wire offcuts as they can be used to extend the remaining wires on the decoder as you’ll see shortly.
The remaining four wires on the decoder are as follows Red & Black, these are the power feed pick-up wires. Orange & grey, these are the two wires to the motor. A simple way to remember which of these four wires goes where is this simple saying:
Red & Black to the track, Orange & Grey to the Motorway
The next thing to note is that on the three screw mounting holes on the chassis that each hole as an insulating ring washer, make sure that when the chassis is re-assembled, that these washers Must also be refitted. The three photos below show each of the screw holes on one chassis block side with the insulating washers.
The best place to fit the decoder on this model is in the cab. As the model doesn’t have a cab interior, this makes our job easier for finding a place to sit the decoder inside the model. On the chassis blocks, on both parts that sit within the cab area of the model, file away a small amount of the blackened chassis as shown in the two photos below. This gives us a good surface to solder the decoder track power feed wires to (the red & black wires).
Make sure all the metal fillings are fully removed as we don’t want them getting in any of the models moving parts.
Temporarily put the two halves of the chassis block back together by taping them together. Then solder the black wire to one chassis block half & the red wire solder to the other chassis block half. As shown in the photo opposite right.
Once the red & black wires have been soldered to the chassis blocks, remove the tape holding the two chassis blocks together.
The next job is to extend the two wires which go to the motor (The orange & grey wires). If you don’t have any spare decoder wire in your toolbox, use the wire offcuts that we cut off earlier. Strip the wire ends & solder one wire on to the orange wire & solder one wire on to the grey wire. Slide a piece of heat shrink over the soldered joint & heat the heat shrink so it permanently stays in place over the soldered wire joints. As shown in the photo opposite right.
Next, solder the orange wire to one of the contacts on the motor, then solder the grey wire to the other contact on the motor. It doesn’t matter which way round the wires go. The two photos below show this process.
Refitting
With the decoder now hard-wired to the motor & the power feeds, it’s time to re-assemble the locomotive.
At the loco chassis front end where the motor fits, wipe clean the recess on both chassis blocks to remove any grease. Then cut & stick a piece of Kapton tape into the front part of the recess as shown in the photo right & below. This will give extra insulation protection against any electrical shorts.
Carefully refit the motor back into the recess in the chassis block. Use a flat-bladed screwdriver to carefully seat down the Kapton tape into the recess around the motor. Make sure the Kapton tape doesn’t foul the screw holes. As shown in the two photos below.
Now would be a good time to clean & relubricate the drive cogs & worm gear with fresh gear lubrication.
Refit the plastic insulating spacers as shown in the photo right. Also, make sure that all the screw hole insulating washers are also refitted. Rescrew the chassis back together.
Sit the orange & grey motor wires within the insulating gap between the two chassis blocks, then stick Kapton tape over as shown in the photo opposite right to hold the wires in place.
Use Black Tak or double-sided foam sticky pad to hold the decoder in place as shown in the photo opposite right. This will also prevent the decoder from touching the chassis block & protect the decoder from any electrical shorts. It’s also a good idea to fit Kapton tape on the chassis block, under where the decoder will sit.
Check that the body will sit back on the chassis block properly. Once happy that the body will refit back on to the chassis block okay, refit the wheelsets/conrods, bottom chassis plate & finally the body.
With the locomotive fully reassembled, place it on the DCC programming track & get the DCC controller to read back the decoder address. It should read back as factory standard address number 3.
Place the locomotive on to the layout & test run it on address number three. We found the model ran very well indeed, so decided to omit fitting the stay alive unit for this DCC conversion project.
After test running the model & happy all was okay, the model was then placed back on the programming track & given a new DCC locomotive address of our choosing. We also adjusted the settings for the loco acceleration & deceleration plus limited its top speed to something more realistic & in keeping with this shunters top speed etc.
We’d like to thank Chris Bower from West Hill Wagon Works for his kind assistance with this DCC conversion project. And we hope this article will be of assistance in converting your own Bachmann split chassis locomotives to DCC.
Happy modelling
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