Installing LokSound Select Direct Micro DCC Decoders in Kato Locomotives

This week’s post is a guest post; I had one of these before from fellow N Scale modeller Mike Musick who wrote an article about improving Con-Cors N Scale U50s, Turbines, and my C-855 by replacing the wheel sets.  This time the article has been written by N Scale modeller Chris Hatt who has written about installing ESU LokSound Select Direct Micro DCC decoders into N scale Kato Locomotives.

So without further ado, I’ll hand you over to Chris.

LokSound Select Direct Micro DCC (part number 73100)

So, ESU recently released to market three new decoders designed to fit in N-scale “Narrow Hood” locomotives. These are locomotives such as the EMD “SD” locomotives (SD40/50/6070/80 and 90 series) and the GE Evolution (ES44 series), AC4400 and Dash-9 type models which have an external walkway down each side rather than a full-width body shell. The body shells on these models are typically around 10mm wide inside.

The LokPilot V4 Direct Micro OEM (#54650) and LokSound Select Direct Micro OEM (#73199) are both designed to partner recent locomotives from InterMountain and Atlas and are available factory fitted or aftermarket to retrofit DC models. The one of interest to me is the LokSound Select Direct Micro (#73100). This is designed to “drop into many pre-2016 Atlas and InterMountain locos, (and others with minor modification)” (http://www.esu.eu/en/products/loksound/loksound-select-direct-micro/). Many people have been asking on-line if they will fit into Kato N-scale models and there have been few answers. As most of my locomotives are Kato and I favour using LokSound decoders to install sound, I decided to find out.

So what do you get?  In the blister pack is the decoder, two 3mm golden white LEDs and two lengths of fine brown-insulated wire for connecting a speaker of your choice. The card backing of the blister pack is a fold-out instruction sheet (the LEDs and wire are between the halves of the card in a zip-lock bag, not in the blister).

Figure 1: The 73100 from the top. The front-end is to the left.

You will note that there are five pairs of metal pads along the edges of the 73100. The two pairs nearest each end of the decoder are frame power pickups, red to the top of the photograph and black below. The pair nearest the center on the narrowest part of the decoder are not labelled on any documentation but careful investigation with a continuity tester showed that these are duplicates of the motor power pads on the underside of the decoder. The pair of pads inboard of the seconds power pick ups from the right are the speaker connections. The tiny yellowish rectangle on the centre-line at the left end is a surface mount 0402 LED connected to output AUX1. This LED is around 1.0mm x 0.5mm!

Figure 2: The underside of the 73100. The front-end is to the left.

The two big pads under the decoder are the motor drive outputs. The front-most is the “orange” output touching the right-hand side of the decoder. Near the back of the decoder are a +ve supply (DCC “blue”) pad and pads for the AUX3 and AUX4 function outputs. At each end of the decoder are a pair of pads spaced for soldering the LEDs for the head- and tail-lights (F0F and F0R). According to the instructions, there are current limiting resistors installed on all the outputs and standard LEDs can be soldered directly to the pads. The supplied 3mm LEDs are not attached so that you can cut the leads to the right lengths to position them appropriately for the model that you are installing the decoder in.
The tiny yellowish rectangle on the centre-line at the right-hand end is another surface mount 0402 LED connected as AUX2. It will be very difficult to desolder the AUX1 and AUX2 LEDs and reuse the pads, so while this is technically a six function decoder, two of them will be nigh on impossible to exploit unless it is possible to pipe the light using optical fibre.

How does it compare to a Kato lighting PCB?

Figure 3 shows the 73100 alongside the lighting and power PCBs from several Kato models.

From top to bottom:
• The PCB from an SD80MAC (also used in the SD9043MAC).
• The 73100.
• A PCB from an SD70MAC (also used in the early-SD70M, ES44AC, AC4400CW, and several others) .
• The revised PCB used in the “screwless” later-SD70M and the SD70Ace. This board has sideways-facing surface-mounted LEDs in place of the 3mm discretes on the SD70MAC board.

All four have the front-end of the board to the left.  Putting the decoder in my micrometer, it measures 0.75mm thick compared to the 0.5mm of the Kato PCB.

Fitting the 73100 in a Kato early-SD70M frame.

The 73100 is closest to the early SD70M/SD70MAC/ES44AC/AC4400CW part so I started there.

Figure 4: The 73100 offered up to a Kato SD70M frame.

Offering the 73100 up to the frame, it becomes obvious that the increase in width of the board at the rearmost but one pair of power pickups means that the decoder will not fit between the frame halves without easing back the blocks indicated in figure 5 below.

Figure 5: Easing the fit of the waist of the decoder.

Shaving off about 0.5mm from each side with a file, Dremel or milling machine ensures clearance. It does not matter if the fit is snug enough that the pads touch the frame because the exposed pads are frame power pickups.

Figure 6: This nub needs to be made smaller.

The slightly thicker board of the 73100 means that the rounded end of the nub shown in figure 6 that presses on the contact pad at the front of the decoder needs to be trimmed slightly. While the decoder will not drop-and-slide-in like the PCB, it can be trapped between the frame halves as they are assembled and it make good contact and is firmly fixed fore-and-aft.

However, powering up the decoder in the frame caused it to go into a rapid short-circuit/shut-down cycle as shown by blinking of the AUX1 LED. Oops!

Careful inspection showed that there were a number of surface-mounted components that could foul the frame halves and pass track power into the decoder by unwanted routes.

Figure 7: Easing the frame around the front of the decoder from above.

Figure 8: Easing the frame around the front of the decoder from inside the frame. Note the trimmed nub on the right.

Carefully trimming back the frames as shown in figures 7 and 8 removes this contact and everything works nicely. Note that the trim is above and below where the decoder will sit to clear components on both faces of the PCB.

Figure 9: Test fitting the decoder.

As you can see, there is a gap under the decoder at the back into which a speaker could fit, but I prefer an alternate location as shown later.

Adding LEDs and the motor connections

Next, head and tail-light LEDs are soldered to the undersides of the decoder. I think that the supplied LEDs are a bit too “golden yellow” for a modern locomotive so substituted “clear white” ones:

Figure 10: Supplied (left) and replacement (right) LEDs.

Figure 11: Head and tail-light LEDs fitted, AUX3 ,AUX4 and “blue” wires attached and motor feeds in place. The headlight is on but dimmed under “Rule 17”.

I have fitted green (AUX3), purple (AUX4) and blue (+ve supply) wires to the underside of the decoder in preparation for fitting separately controlled ditch lights later. I provided feeds from the decoder to the motor brushes by using strips of phosphor-bronze 1/16th of an inch wide and 5 thousands of an inch thick (1.6mm x 0.12mm) soldered to the appropriate pads on the decoder. These are pressed against the motor brush tabs by the body shell very much like the connections of the original lighting PCB. To prevent these from contacting the frame-halves, yellow “Kapton” tape has been wrapped around the frame rails under their path. In addition, I placed a strip of Kapton tape under the headlight and under the rear of the decoder to ensure that nothing touched the frame there. This is particularly important at the back as the solder joints attaching the purple, green and blue wires would otherwise rest on the frame.

And, of course, a speaker

My preferred location for the speaker is at the back of the frame. By trimming off the shaded area in figure 12, space is made for an 8mm x 12mm “sugar cube” type speaker (although I buy mobile phone spare parts on eBay rather than commercial “railway modelling” speakers).

Figure 12: The bit of the frame I remove to make room for a speaker.
A suitable baffle can be constructed from plastic sheet, purchased commercially or 3D printed (James does some). I attach the speaker baffle to the end of the frame with an adhesive “sticky dot as in figure 13.

Figure 13: The speaker installed.

The baffle provides most of the insulation needed to keep the speaker from contacting the frame but a short length of Kapton tape on the shelf underneath adds to the protection.

And that’s it, bar loading a suitable sound project and configuring the decoder:

Figure 14: A short video of the installation using the “Drive Hold” feature of the decoder to stop it moving while changing the throttle setting. Still got the ditch lights to do!

That is certainly easier than milling out the fuel tank to take a LokSound Micro V4 or LokSound Select Micro and also leaves the locomotive somewhat heavier as less metal is removed:
• With a Digitrax DN163K1C non sound decoder 116g
• With an ESU LokSound Select Direct Micro and speaker 114g
• With an ESU LokSound Micro V4 and speaker 105g
and weight equals tractive effort.

Figure 15: The same kind of frame with a pocket milled in the fuel tank to take a LokSound Micro V4 (or Select Micro), with channels through the back of the fuel tank, across the bottom of the frame and up the sides to get the wires to the lighting PCB to hook the decoder up.

Where next?

Next, the SD80MAC/SD9043MAC and the late-SD70M/SD709Ace.

I leave you this week by saying thanks to Chris for his post and I look forward to his how-tos on fitting LokSound Select Direct decoders into other locomotives.

Improving Kato UniTrack HO Points for DCC Operation

Kato UniTrack is a very good product and allows reliable trackwork to be assembled quickly without the need to cut and solder track.  Most Kato turnouts, including N scale, have the ability to be switched between power routing and non-power routing, but the No.4 HO turnout, as pictured below, doesn’t. So in this week’s post I’ll show you how I modify Kato UniTrack No.4 turnouts for use with DCC.

But what does power routing mean?  Below is an extract from www.dccwiki.com showing how the turnout isolates different routes depending on how it’s set.

For DC operation, power routing is very useful as power is delivered only where you want the train to run.  The other route is isolated so any trains on that line won’t move.  However for DCC all the tracks want to be powered so the turnout ideally wants to be non-power routing.  As I said earlier most Kato turnouts can be switched between power routing and non-power routing but the HO No.4 can’t.

In the No.4 box you get the actual turnout and associated track parts.

The actual turnout has an all metal frog shown in green, electrically linked blades shown in yellow and switched rails shown in blue.  The stock rails are marked red and black; these have the incoming power.

Between the frog and the switched rails is a plastic insulator.  It’s these two rails which ideally need to be electrically connected permanently for DCC operation.  However the frog changes polarity depending on how the turnout is set so you simply can’t solder the switched rails to the frog.

On the underside of the turnout are five screws holding on the base plate.

Under the base plate you can see the electronic switch and the solenoid which changes the turnout.  In the image below the turnout is set for the straight route. The ‘T’ section in the center of the switch is connected directly to the frog and bridges power from the right side to the left.  This connects the frog and the relevant exit rail or switched rail back to the black stock rail.

In the image below the turnout is set to the diverging route and the ‘T’ section connects the switched rail and frog back to the red stock rail.

To make the turnout non-power routing is a fairly simple fix.  I use two short sections of wire, as shown below.

These two wires are soldered to the copper plates as shown below.  The upper wire links the red stock rail to the diverging switched rail.  The lower wire links the black stock rail to the straight switched rail.

And that’s it.  This modification also makes the turnout even more reliable as the power is transferred through the new wires rather than the contacts in the ‘T’ sections.

With the base plate replaced the turnout is ready for use on a DCC layout.  It can still be used on a DC layout, the turnout simply won’t act as a power router. Also, if you’re not into soldering, this modification can be done away from your layout at a model club or possibly a local hobby store as the Kato turnouts will remain self-contained.

How to Fix Runaway Locomotives on a DCC Layout

When running your layout on DCC power have you ever had the problem of trains suddenly rocketing off down the track at full speed for no apparent reason?  Well a fellow modeler had just this problem this weekend.  So in this post I will explain what was causing his issue and what you can do to avoid it.

Before I can say why there’s a problem I need to explain a bit about how DCC works.  DCC powered trains all have a decoder inside which receives power and instructions through the track.  This combined supply is a 12V to 16V AC (Alternating Current) signal.  The decoder splits this into two separate parts.  The first part is the AC power which runs through a bridge rectifier.  This converts the AC power into 10V to 12V DC (Direct Current).  The DC is used to power the decoder and any outputs, such the motor and lights.  The second part takes the instructions, which are carried in the AC Bi-polar Square Wave as packets, and feeds them into the decoder processor.

(A Bi-polar Square Wave is not the same as a Sine Wave which you may have seen on an Oscilloscope screen trace; one is a series of square shaped variable width pulses and the other is smooth curved [Sinusoidal] and has a constant period time-base. The DCC signal as well as being square in shape has a variable time-base. By varying the width of each square wave pulse, a digital binary data bit can be transmitted. A binary 1 or a binary 0. It is the pattern of ones & zeros that define the DCC command being sent.).

The instructions will be things like increase speed or turn on light.  The DCC command station sends out many packets every second, that’s why the decoder can do many things at once.

A lot of decoders have the ability to run on traditional DC powered (Analog) layouts as well as DCC.  This is achieved by the processor understanding what type of power it’s receiving.  For example, if a locomotive with a suitable DCC decoder is put on a DC layout there will be no power applied until the DC throttle is turned on.  As the processor starts to receive a DC power supply but no information packets it realizes it’s on a DC controlled layout; this takes barely a second.  So it bypasses all of its complicated circuits and sends any DC power received directly to the motor and lights.  This makes the locomotive behave just like a normal DC locomotive.  It repeats this every time it’s moved on a DC layout.

The next time the locomotive is put on a DCC layout the second it receives an information packet it knows it’s on a DCC supply and returns to normal.

In an ideal world this works well and there should never be an issue, but things can go wrong and the primary cause of locomotives rocketing off down the track is short-circuits.  These are usually caused by derailing trains or when you’re putting rolling stock onto the layout whilst the track power is on.  Especially steam engines with lots of wheels!

So why does a short-circuit cause an issue?  When a DCC command station detects a short it turns the power off.  Some will keep trying to turn it back on or will require you to do it manually.  Situations where you have several quick short circuits, for example putting on a steam locomotive, can cause the command station to repeatedly start up and sending out its packet information as it turns the power back on.  If the decoder in the locomotive doesn’t receive a full packet it ignores it.  If this happens too many times on start-up it may get confused and think it’s receiving no packets of information and switch itself to DC.  The problem now is that it will bypass its processor and feed the full 10V to 12V DC from the bridge rectifier directly into the motor and the locomotive rockets off.

This situation can also happen if a train runs into a point or turnout which is set against it.  The system shorts, you change the point, the trains moves forward and shorts again as some wheels have derailed, you lift the derailed item, it shorts again but re-rails itself, the power comes on and other locomotives on the layout rocket off on a joy ride.

So what can you do to stop this? My advice would be to turn the DC running option off on all of your decoders.  This does mean they simply won’t work on a DC layout so bear that in mind if you run them on both.

So how do you do this?  If you have a computer connected to your layout or programming track it should be fairly easy.  Each brand of software is different but the principle is the same.  I use Decoder Pro from JMRI for my programming and the very first screen when you start programming a decoder looks like this.

Below the locomotive address options is the switch for turning off the DC operation.  In the advance setting or Comprehensive Programmer the option is in the basic tab and there is often a tab dedicated to just Analog Control.

But what if you don’t have a computer connected to your programming track?  The option to turn the DC on and off is contained within the CV (Configuration Variable) settings: CV no 29 controls this.  But it also controls the locomotive direction, the speed step settings, Railcom Settings, Speed Curve Settings, long address option and sometimes more, depending on the decoder.  So to work out what number to set CV29 to there are several calculators available on-line to work it out.  This page on Digitax’s website has several CV calculators and the second one down is for CV29.

If you are programing this CV change on an existing locomotive in your collection, rather than a brand new install, it’s a good idea to read CV29 first and see what the value is.  Then replicate this value in the calculator before making the change.  That way you won’t be changing something you don’t want to.

The 2mm Scale Association also has a good calculator here.

Some of the more expensive decoders are smart enough not to suffer from this but I tend to always turn DC off on them all, just to be safe.  Plus if you intend to install any Stay Alive systems to your locomotives you will need to turn it off anyway as a Stay Alive delivers DC power only and it could confuse the decoder again.

With all your locomotives set this way you should have a rocket free layout!

Adding Real Coal Loads To Hoppers

Happy New Year!

2018 is here and after a little time off over the Christmas holiday I’m ready to get stuck back into modeling, 3D printing and generally anything train-related.  And what better way than a blog post about something I’ve been working on that you can also do.

Over the years I’ve collected many different coal cars and the only thing I don’t like about them is the identical plastic coal loads.  So this week’s post is a ‘how to’ for adding real coal loads to hopper cars.

Of course modern block coal trains do have very similar loads in the cars because they are all filled from the same place at controlled intervals and look something like this. (Photo taken by Lewis Bogaty, see his blog here)

But depending on where the load comes from will depend on the size of coal pieces as shown in the image below. (Photo from Virginia Tech Imagebase).

The shape of the load is also effected by the type of coal chute and the operator.  For me I like my coal loads to look something like the cars below; with a twin mound and a random unevenness.  These are Lionel O scale cars, and if you look closely you can see the coal loads are identical!

So what do I do?  Firstly I pick a coal to use; I’ve been using Woodland Scenics’ Mine Run coal, it’s not actually coal but looks just like it and it weighs next to nothing.

Unless the car has a load which is the right shape and set low in the car (I’ll explain what to do with those later) I remove the original load.

This would also be the best time to add any weathering to the car so it doesn’t get onto the coal load. But for this particular car I haven’t done that as it already has a grubby look.

Next I cut a piece of rectangular card which is the same size as the top the car.  It doesn’t have to be an exact fit but it wants to be snug.

The card wants to be set down from the top rim.  This has two functions, it gives me a level to work from and saves me filling the whole car with coal.

To hold it in place I use a splash of super glue on each end.  Any glue will do but I like to do this fairly quickly and superglue sets very fast.  In my previous posts you may have seen me use the Gel superglue which I normally prefer as it doesn’t run.  But today I want it to run into the gap so I’m using the regular stuff.

Next I cut a second strip of card which is thinner than the original, about half as wide.

The second strip is then cut into two pieces.  These will form the mounds, and if you want three mounds simply make them shorter and add a third.

Using my craft knife I cut the mounds at forty-five degrees to make a chamfer.

I repeat this on all four sides.  It doesn’t have to be perfect as it’s going to be covered with coal!

I then put some super glue where the mounds will be.

And place the mounds, trying to get them centered in the car.

Next I use a white glue, simply placed in the car as below.  Woodland Scenics’ Scenic Cement will work or any white glue but I like to use Tacky Glue, simply because it sets quickly and speeds up the operation.

Using and old brush I spread it all over the card trying not to get any on the top edge of the car.

Then the fun bit, simply pour the coal on top.  I recommend doing this on a piece of paper so the excess coal can be picked up and reused.

After about 5 minutes, if you are using Tacky Glue, turn the car over and all the excess coal will fall off.

Pick off any bits that have stuck to the top edge before they set permanently.

If, like me, you want the mounds to be a bit higher simply add a bit  more glue to the top of the mounds.  Also if there’s a hole or gap add some glue there as well.

Then re-cover the car with coal.

After another 5 minutes tip over again to remove the excess and you should be left with a natural-looking load of coal.

I then leave the car overnight just to make sure all the glue sets.  And the car is now ready for the railroad.

Earlier in the post I spoke about cars which have a plastic load which is the right shape and set low in the car.  When the load is set low there is room on top for extra coal without it looking over full. These are easy to do, simply cover the plastic load with white glue, again avoiding the top edge, and pour on the coal.  Even though the plastic loads will be the same shape the poured on coal will take a slightly different pattern each time.

And that’s it for the first post of 2018, I will be back next week with more. In the meantime I’d just like to wish you a great New Year and I look forward to sharing more of my train projects with you.

Lubricating, Oiling and Greasing Locomotives

As well as 3D printing model trains and building model railroads, I do a lot of repairs to locomotives for fellow modelers. These range from simple wire repairs up to total motor and chassis rebuilds or replacements.  One of the issues I come across is over lubricated locomotives, so in this post I will tell you a bit about why this is a problem, and how it should be done.

Some people have said that liberally lubricating moving parts will help preserve them if they are going to be stored for a long time and I can assure you this is not the case.

Over lubricating a locomotive can have the following progressively worsening effects:

It can cause the locomotive to lay a film of lubricant on the rails making the locomotive and others loose traction.

It can make it slippery to handle and possible damage the paint work.

It can make it easy for the mechanism to retain dirt and fluff, which will start to cause binding and over strain the motor.

Oil inside the motor, or on the commutator, can disrupted the flow of electricity to the motor making it run slow or roughly. (What is a commutator? see the image below).

Oil inside the motor on the armature can connect parts of the motor to the power or chassis causing arcing and bad running though intermittent shorting. (What is the armature? see the image below).

And the biggest problem, oil coating the commutator and brushes which will cause a dead short.  This will in turn cause the motor to overheat and burn out; this is when the small gaps between the commutator plates blend into one, so the electricity just passes straight through.

I often get locomotives to repair where there has been smoke coming from the motor or a glow and buzz, rather than turning.  This is normally a sign that the motor has become jammed or the commutator is shorting.  The glow is lubricant and carbon, from the brushes, stuck between the commutator plates acting like a bar fire element.  The smoke is usually the excess oil burning off from the heat being produced. If the commutator or brushes are heavily lubricated electricity simply doesn’t go where its supposed to.  Sometimes if a motor gets to this stage it can get deformed from the heat and will never run as well as is should again.

One other issue I sometimes see is if the wrong type of lubricant has been used.  Some are not plastic friendly and can cause gears and parts to break down.

So what should you do?  The simple answer is ‘just a few drops will do, don’t over lube’ and this is the phrase on the package of the main lubricant I use from LaBelle.

Being an N Scaler I tend to use lubricants from LaBelle as they have a set designed specifically for N scale which are plastic friendly and very fine, but the principles are the same for all scales.

The three products in the kit are oil, gear lubricant and grease.

LaBelle 108 is a very fine oil with a high viscosity.  It is used, sparingly, for moving metal components like valve gear and side rods on steam engines.  It can also be very sparingly used on motor bearings and brush slides etc. but try not to get any on the actual brushes or commutator. (LaBelle 107 is designed more of larger scales such as HO and O).

LaBelle 102 is heavier than the oil but not as thick as grease and is designed for exposed gear boxes.  It contains PTFE (Polytetrafluoroethylene) which has been called “the slickest substance known to man” and is the parent chemical of “Teflon” which is a registered trademark of Dupont Chemicals.  It’s great for metal gears and axles.

LaBelle 106 is a grease, which also contains PTFE.  Their slogan is ‘just a dab’, and they are right.  It’s designed for plastic gear boxes and worm gears.  A dab on one of the gears will work its way through the box and onto any worm gear.  Again, a dab is all you need, over lubricating with grease could start to bind the gear box.

There are lots of companies making similar products, and any good model shop should be able to guide you to the right one for your model.

But which ever you decide to use, remember just a drop is enough.

Fitting DCC to Wrenn OO Locomotives – Vertical Motors

Last week’s post was all about converting Wrenn OO locomotives with horizontal motors to DCC; you can find the post here.  This week I’m going to share with you how to convert the vertical motors.

The vertical motors were used in the City & Duchess 4-6-2s, A4 4-6-2s, 0-6-2 tank engines, Royal Scott 4-6-0s and Bullied Pacific 4-6-2s.  The two engines I’m converting are the ‘City of Birmingham’ and ‘Sir Nigel Gresley’.

To remove the all-metal shell simply remove the screw located at the front and it will come away from the chassis.

As with the horizontal motored locomotives the wiring is very simple.  The black wire goes to the right side pickups and connects to the isolated motor brush at the front of the motor.  The brown disc is the capacitor which acts as a suppressor to prevent interference with televisions etc.  The other wire from the capacitor connects to the chassis and the left side pickup.

All the wires are removed except the black feed from the right side pickup.  The brush at the rear of the motor is not isolated from the chassis and, as with the horizontal motor, it’s this one which gives us a problem.

The steel cap covering the brush simply pulls out to reveal a spring and a brush as below.

The cap fits into a brass sleeve which guides the brush and spring to the armature.  In order to isolate the brush from the chassis this sleeve will have to be removed and replaced.

It’s very unlikely the sleeve will push out; you may be lucky but chances are it will need to be drilled.  Before you do this the armature will need to be removed to prevent damage and metal filings getting where you don’t want them.  In the picture above you can see I’ve removed the magnet and side plates: this is done by removing the main bolt through the motor.  The front brush should also be removed by pulling the end cap out.  Then the top nut above the armature can be loosened and unscrewed.  Note there is a small ball bearing in the cap. The grease should hold it there but be prepared for it to fall out. Then the armature can be removed, normally from the right hand side.  There’s also a small ball bearing in the fitting at the bottom of the armature. Again, it should stay in place but be ready just in case.  The chassis should then look like this.

Using a 5mm drill the old sleeve can be drilled out and the hole made ready for the new 3D printed sleeve; you can see the new sleeve in the bottom right of the image above.  Once the hole has been drilled, clean and remove any burrs from the hole and remove any metal fillings from the chassis.  Before you fit the new sleeve make sure the brush fits through without any resistance.  It should be able to fall through if tipped up.  If it sticks there may be some 3D printing residue inside which can be removed with a drill bit or round file.  The new sleeve can now be fitted and, if necessary, held in place with a little glue.

Then simply reassemble the motor.  Before you put the armature back in check to make sure the ball bearing is still there.  The top nut should be screwed down so the armature spins freely but has no vertical movement; only then should the nut be tightened.  With the brushes refitted, a continuity test should be done with a volt meter to double-check that both brushes are isolated from the chassis.  Then the wires can be added for your DCC decoder.  The red goes to the black wire, the black goes to the chassis, the orange goes to the front motor brush and the gray goes to the rear as below.

Once a DCC test has been performed the shell can be refitted and the loco is good to go.

So where can you get these 3D printed isolating brush holders? They’re available here:

Two Wrenn horizontal motor isolating sleeves.

Four Wrenn horizontal motor isolating sleeves.

Two Wrenn Vertical motor isolating sleeves.

Four Wrenn Vertical motor isolating sleeves.

Two Wrenn Vertical & two horizontal motor isolating sleeves.

I will also keep a few in stock so please drop me an email or message me through the contact page.  If you have a different locomotive which needs a special part to isolate the motor for a DCC conversion I’d be happy to look into it for you.