Bachmann Mk1 SK Coach lighting (39-026)

[Art Dent]

Here is another lighting conversion for a Bachmann BR Mk1 Corridor Second (SK) code (39-026)

 

This article was first published on ModelRailForum in January 2017.

 

As part of my continuing lighting efforts, I purchased a second-hand Bachmann Corridor Second (SK) and a lighting kit and assorted wiring bits and bobs from layouts4u.net

Part 1 - Disassembly, painting and interior detailing

First, a picture of the coach in question (as purchased):

 

 

The first thing to do to gain access to the interior of the coach is to remove the three retaining screws on the underside of the body.

One screw is on the centre-line, mid-coach, between the frames and is easily located and removed. The other two are hidden by the

bogies and close-coupler which has to be extended and moved out of the way to gain access:

 

 

Remove the three water-filler pipes from the ends of the coach (two on one end, one on the other). This picture shows the toilet end

of the coach and where the wire fits.

 

It needs to be carefully teased out with a thin flat blade (a Stanley knife blade is ideal) between the lower end of the pipe and the

body (just above the arrow).

 

 

Body and roof will now separate from the chassis as a complete unit - however the two coach body sides are clipped to the roof (in

five places each side if I remember correctly) and the sides may separate from the roof by themselves at this point!

 

 

To separate the body sides from the roof, turn the complete assembly upside-down then gently prise apart the two body sides at one

end whilst lifting the end of the interior/seat moulding. Working from one end like this enables the interior to be easily removed.

The body sides can now be separated from the roof by gently easing the bottom ends (floor end) of the sides away from each other.

Once a clip springs, you can again apply a wide, flat blade (Stankley knife blade, guitar plectrum or cut-up credit card) into the gap

between the top of the body side (roof end) and the roof to spring the remaining clips.

 

A combination of rocking the body side back and forth whilst using the knife blade to release the remaining clips.

You should be rewarded with two separate body sides, the interior moulding and the roof:

 

 

In comparison with the BCK coach that I fitted a working tail light to (link here and here) where the glazing appeared to be a single

strip on each side (although with hindsight, it appears that it wasn't), several of the glazing panels came loose on this coach (there

are five on each side), so I decided to remove them all from both sides of the coach and re-glue them in back place (after carefully

noting which went where and on which side) after painting the interior of the body with Humbrol matt wood (110) to prevent light-bleed.

I printed off another sheet of the Peco/Kitmaster 2nd class coach interior for detailing.

The seats on the BCK coach can be individually removed but in this coach, the compartments and seating are a single moulding:

 

 

This made the application of the seat coverings and subseqent trimming rather tricky!

 

 

The above picture was taken part-way through painting the inside of the compartments with the matt Humbrol paint.

 

As I was taking the coach apart to see what was what and to fit the seat coverings, the morning post arrived with the lighting strip

and pickups, stay-alive and sub-miniature plug & socket (so that the coach roof can be completely removed at a later date if necessary)

- talk about timing!

 

 

The stay-alive is quite small (around 23mm x 11mm) although this is version 1 - there is a 'new improved version with a

potentiometer included to 'tune' the brightness level but it is significantly bigger.

 

 

and

 

 

It was this that prompted me to manufacture my own stay-alive/anti-flicker units (firstly using stripboard with a circular bridge

rectifier and then later omitting the stripboard altogether as these two images show):

 

DIY Stay-Alive v1:

 

 

DIY Stay-Alive v2:

 

 

The only place to ''hide'' the stay alive was either in the toilet or in the corridor. It just fitted in the corridor and the height of the
stay-alive just matched the length of the corridor section. It was a tight squeeze - so no need to glue it in place.

 

Viewed from the side it is barely noticeable - especially if you paint the 'silvered end' of the capacitor with matt black paint.

 

 

and

 

 

The stay-alive pcb was fitted with the socket ...

 

 

... which was then subsequently super-glued to the side of the capacitor to stop a stray from lead fouling anything when

re-assembling the coach.

The 12 LEDs on the strip don't quite align with the eight compartments (no surprise there) ...

 

 

and

 

 

... so I debated whether to [1] cut the strips or [2] paint over the odd LED (otherwise some compartment would have two LEDs
whilst others would have one).

I was tempted to go thinking with option [2] although in the end, I went with neither, simply arranging the LED strip so that nothing
fouled the compartment bulkheads as a lighting test showed that there was not much difference between compartments with two
LEDs and compartments with one!

I cut a strip of aluminium kitchen foil to size and glued this on the underside of the roof to aid with making the illumination more even.

 

 

As this post is already of biblical proportions, I'm going to split it here. In Part 2 I will detail the wiring of the pickups, testing
and completion of the coach.

Cheers,

Art

 

 

 

 

 

 

 

Edited April 6, 2019 by Art Dent

[Art Dent]

Part 2 - Pickups, wiring, testing and completion

 

In this second and final part, I detail the troubles with pickups and wiring as well as testing and completing the project.

 

The lighting kit from layouts4u comes with two phosphor-bronze pickups and some small screws. Initially I thought that
these would be a better option than my previous pickups from DCC Components (DCF-WP12), however with the Bachmann
coach (and its close-coupler) the DCC Concepts pickup introduces some tricky problems ...

 

Fitting the contact strips to the bogies is easy. You need to drill a 1.0mm hole to accept the screw (here I'm using a 0.95mm
drill and a pin vice).

 

In the BCK I had these strips rubbing on the back of the wheels (which were blackened and had to be cleaned, so
here I opted to have the strips rub on the tops of the wheels:

 

 

Remember to solder the wire onto the strips BEFORE fitting to the bogie (unless you like melted plastic) - a tiny drop of
solder flux helps enormously (applied with the end of a matchstick). It makes for a nice, neat, unobtrusive job.

 

As before I cut a curved slot into the floor of the coach. The two thin feed wires pass through the slot.

 

 

and

 

 

Testing all four wheels, pickups and wires for continuity using a DMM is a good idea at this stage (all was good).

 

The coach was then rested on the bogie and the bogie checked to see if the pickups fouled anything - and they did!

 

There is a very small gap between the inner end of the bogie and the underside of the coach and the pickup strips were

fouling on both the inner and outer ends. I thought that bending the strips downwwards cure the problem and it did

- partially. The strips still seemed to be fouling on two small protrusions marking the end of the underframe - and these

were removed with a Dremel and a Stanley knife blade.

 

Pickup strips as originally fitted - notice how the straight end of the pickup strip protrudes slightly?  

 

 

This fouled on the underside of the coach when the bogie was fitted meaning that the bogie couldn't swivel freely.

 

I wondered whether bending the end of the pickup strips would work.

 

Picture of the fix where the end of the strips are now bent downwads slightly to aviod fouling on the underbody of the coach.

 

 

This allowed free movement - until I removed the bogie and re-fitted the close-coupler to the bogie. These close couplers

really are a HUGE PITA as far as coach lighting goes - they are ALWAYS getting in the way somehow!

 

The wires have to pass through the body where the close-coupler spring is and this causes a problem as the feed wires

foul on the spring. I drilled two single holes - one each side of the spring to get around this but then enountered another

problem. You need some 'spare' wire to allow the bogie to move left & right and the further away from the bogie pivot,

the more spare wire you need.

Also, the supplied wires, fine as they are, are a bit too thick to go between the coach chassis and the interior moulding.

 

The thin red & black insulated wire as supplied with the lighting kit is around 0.6mm in diameter. Fine, but the gap

between the underside 

of the interior moulding and the coach floor means that these wires are 'pinched' and this prevents free movement of the bogie.

I thought that would be solved by cutting away around 1.5mm of the floor of the interior moulding and whilst I had the Dremel out, I
ground away around 1mm (the thickness of the pcb) at the end of the gangway to allow some extra room for the wiring.

 

Before attempting to route the 0.6mm wire around to the sides of the coach, I decided to abandon this approach and use some of the
spare enammeled wire that I had from the loco lamps.

 

This fine enamelled 'loco lamp wire' is around 0.1mm in diameter (although this causes its own problems - see later).

 

 

Above - the 0.6mm wire as supplied in the lighting kit and the enamelled 'loco lamp wire' for comparison.

 

This wire is so fine that if you drop it on a patterened carpet it is almost impossible to see (as experience has taught me).

So, back to the pickups and bogie #2...

 

I cut another curved slot cut INSIDE the close-coupler and fitted the fine enamelled wire to the pickups and the pickups to the bogie

 

 

and 

 

 

and

 

r

 

You can see here how the close-coupler spring interferred with the first slot that I cut.

 

The feed wires to the stay-alive board were shortened and soldered to the feed wires from the bogie together with a 1k5

series resistor.

The coach was then placed on the programming track to check the brightness levels.

 

It worked and the brightness seemed to be OK!

 

 

... even better in the dark ...

 

 

The strip was then stuck to the underside of the roof and the body-sides fitted to the interior seat moulding.

 

 

The coach was then populated by a sprinkling of Bachmann Scenecraft seated coach figures (36-408) strategically placed t

 hide the odd glue mark when sticking the seat covers in and the capacitor painted with what was supposed to be matt

black paint ...

 

 

... and from the side it is quite unobtrusive.

 

 

Another quick check before the roof was clipped on to complete the installation.

 

Finally, some pictures of the completed coach.

 

The capacitor is really very hard to see (would be even harder if I'd mixed the matt black paint thoroughly):

 

 

The illuminated coach looks very good (IMHO). First one side (corridor):

 

 

and then the other (compartment side):

 

 

Now all I need to do is apply some light weathering!

 

Hope you have enjoyed looking at this and that it has in some way inspired you.

 

Given the lack of room inside the coach to fit the stay-alive board and the tremendously irritating close-coupler (it gets in the

way constantly) this is not a project to be undertaken lightly (or, indeed, not at all for those with little or no patience or

long-sighted people!)

 

Hope you find this useful / informative / inspiring!

 

Take care,

 

Art

Edited April 6, 2019 by Art Dent

[Phil Bullock]

Really like the final result Art!

 

But a suggestion.... having pick ups rubbing on the wheel rim creates the maximum possible drag as the wheel diameter is maximised at this point.

 

Where I have fitted working tail lamps on Bacchy Mk1s for the pick ups I have fitted a strip of copper clad inside the bogie frame - thats underneath the frame rather than on top - and soldered the pick ups - which bear on to the back of the wheel as near to the centre as possible to minimise drag - and the wires to the lamp to this. Before fitting of course to avoid melting the bogie. Has worked well on B1 Commonwealth and B4 bogies

 

Keeps everything away from that close coupling mechanism !

 

Cheers

 

Phil

[Art Dent]

12 hours ago, Phil Bullock said:

Really like the final result Art!

 

Thank you.

 

12 hours ago, Phil Bullock said:

 

But a suggestion.... having pick ups rubbing on the wheel rim creates the maximum possible drag as the wheel diameter is maximised at this point.

 

Where I have fitted working tail lamps on Bacchy Mk1s for the pick ups I have fitted a strip of copper clad inside the bogie frame - thats underneath the frame rather than on top - and soldered the pick ups - which bear on to the back of the wheel as near to the centre as possible to minimise drag - and the wires to the lamp to this. Before fitting of course to avoid melting the bogie. Has worked well on B1 Commonwealth and B4 bogies

 

Keeps everything away from that close coupling mechanism !

 

Cheers

 

Phil

 

This was my second (or third) attempt.  The first time I had the pickups on the underside of the bogie rubbing on the backs of the wheels - but these had been blackened and this had to be removed - so I tried a different approach with this one.

 

You make a great point of having the pickup rubbing as close to the axle as possible.  Thank you.

 

Art

[Phil S]

Conductive paint can, in theory, be used to bridge over the insulation of 1 wheel, so as to use the metal axle as pickup.

The most recent 'bottle' of it I bought seemed runnier/thinner than earlier/other versions -  you need to ensure it will enter and bridge any 'gap' between materials ... down to near 0 ohms    ( not such a problem for simple resistive axle detection )

Maybe degreasing with alcohol would help before painting??  or de=blackening