Heljan BR class 02, conversion to S7

[RichardG]

Do I spot that the PCB is 21pin with a 470uf capacitor already in place for when a decoder is added?

Yes the decoder connector is a MTC21.

I have rung out the connections to the 470uF capacitor and it is indeed connected across pins 16 (+) and 20 (gnd). So we have a simple stay-alive built into the motherboard on the loco.

While I have the blanking plug detached, the 21 pin header on the motherboard is 2.5 mm tall. So any decoder having underside components less than 2.5 mm tall should fit.

 

[Bob Essex]

That’s useful so long as the PCB also has the other bits in circuit for what is needed, which I presume it does, although TBH 470uf is pretty paltry for 7mm and especially if it’s just an electrolytic rather than tantalum. One question that springs to mind is how that might work with the Zimo 21-pin types. The two they make, sound/silent, both come with onboard capacity for 16v tantalums and presently a 1000uf comes already attached. I wonder what conflict might arise.

Bob

 

[RichardG]

That’s useful so long as the PCB also has the other bits in circuit for what is needed, which I presume it does, although TBH 470uf is pretty paltry for 7mm and especially if it’s just an electrolytic rather than tantalum. One question that springs to mind is how that might work with the Zimo 21-pin types. The two they make, sound/silent, both come with onboard capacity for 16v tantalums and presently a 1000uf comes already attached. I wonder what conflict might arise.

I have no experience of the 'managed' stay-alive units using a three-wire connection, but I have added extra capacitors across the power rails of decoders with no obvious problems. This is what Heljan are doing here.

Connecting capacitors in parallel makes one bigger capacitor, just add the values together. I don't honestly think there will be a 'conflict'. As an engineer I would expect to double the voltage rating of an electrolytic i.e. twice its operating voltage, and so a 50V not a 25V electrolytic here. However I have looked inside enough consumer electronics (and model trains!) to know that modern manufacturing is pretty cheeseparing. And my education was forty years ago.

I have dug out the multimeter. The Heljan class 02 is drawing 210 mA running forwards and 190 mA reverse on a rolling road. The figures on the layout with a short train (six wagons) are less than 260 mA. The maximum constant current draw I can achieve is 320 mA, this is during wheelspin getting 14 wagons underway.

The motor is physically quite small for an 0 gauge model, perhaps it is a coreless one. So I am not terribly worried about the size of the 470 uF capacitor.

I have bought a s/h LokPilot, so I'll find out what the capacitor achieves next week. There is free space below the motherboard which could take more capacitors.

 

[spikey faz]

Hi Richard.

When I converted my Ixion Hudswell Clarke to S7, I used Slaters wheels (turned to S7 by Col ).

The Ixion bearings and drive gear were reamed out to accept the Slaters 1/8 axle. There's an article on the S7 website on how to do this.

If you could apply the above to your model, I guess you'd have to make new pickups and maybe add some dummy frames to bulk things out a bit.

Just my thoughts.

Mike

 

[RichardG]

The Ixion bearings and drive gear were reamed out to accept the Slaters 1/8 axle.

Hi Mike.

This approach went through my mind too, but the class 02 needs 3ft 6in wheels. Sadly these can only be had from Slater's with a 3/16 inch axle.

To be honest, I think the HJ chassis will take a HJ wheel and nothing else. A mate has just described the innards of the Tower Models 02 to me, and I know one of these (even a workshop model) isn't going to satisfy me either. I had best be happy with what I have, or build a new chassis.

 

[spikey faz]

Hi Mike.

This approach went through my mind too, but the class 02 needs 3ft 6in wheels. Sadly these can only be had from Slater's with a 3/16 inch axle.

To be honest, I think the HJ chassis will take a HJ wheel and nothing else. A mate has just described the innards of the Tower Models 02 to me, and I know one of these (even a workshop model) isn't going to satisfy me either. I had best be happy with what I have, or build a new chassis.

Ah! Thats a shame about the axle diameter.

Well, I've seen what you did on your other thread about turning wheels to S7. I reckon you could do the same here.

Mike

 

[Yorkshire Dave]

The slots in the inner chassis accept the wheel bushes, and are 4.5 mm wide. This rules out putting Slater's axles directly into the factory chassis.

Reading the thread thus far it seems there are a lot of trees creeping in with the wood disappearing . As I understand the Slaters wheels for the BR class 02 shunter are cat no. 7842/02 which have 3/16'' (4.7625mm) axles.

With access to a lathe couldn't you skim 0.13125mm (0.2625/2) off the Slaters 3/16'' (4.7625mm) axles to reduce them to 4.5mm. This will still leave the square end with a shoulder for the wheel to back up to.

This will allow the them to drop into the existing slots. If it's possible to obtain the final drive gear as a spare part this will avoid using the gear off the standard wheels and you'll then have S7 and O scale drop in wheelsets.

 

[RichardG]

Reading the thread thus far it seems there are a lot of trees creeping in with the wood disappearing . As I understand the Slaters wheels for the BR class 02 shunter are cat no. 7842/02 which have 3/16'' (4.7625mm) axles.

With access to a lathe couldn't you skim 0.13125mm (0.2625/2) off the Slaters 3/16'' (4.7625mm) axles to reduce them to 4.5mm. This will still leave the square end with a shoulder for the wheel to back up to.

This will allow the them to drop into the existing slots. If it's possible to obtain the final drive gear as a spare part this will avoid using the gear off the standard wheels and you'll then have S7 and O scale drop in wheelsets.

Dave I could do all of this. If I arranged the Slater's axles to be split axles, I wouldn't need to add new pickups for the S7 wheelsets.

What puts me off is the imbalance of engineering standards I would be creating, with good quality wheels married to a low-rent motor and gearbox and sitting in a rigid chassis. And these very soft metal side rods. If I go for Slater's wheels, I'd want to make a new chassis from scratch and use a better motor and gearbox. I think this would give me more satisfaction during the rebuild and in the long run, though I realise this is a purely subjective thing.

What is creating a particularly distracting "tree" is, having flattened out the curved side rod the model is running rather well. So I'd like to start the conversion on the bodywork, to sort out some of the less "scale" details. I do usually write about what I have done rather than what I want to do (it brings less back-tracking!) but the heatwave this week is making rattling on here so much more enjoyable than leaning over a hot soldering iron.

 

[adrian]

Reading the thread thus far it seems there are a lot of trees creeping in with the wood disappearing

It does seem to be the case here.

This will allow the them to drop into the existing slots. If it's possible to obtain the final drive gear as a spare part this will avoid using the gear off the standard wheels and you'll then have S7 and O scale drop in wheelsets.

This would be my solution.

Dave I could do all of this. If I arranged the Slater's axles to be split axles, I wouldn't need to add new pickups for the S7 wheelsets.

Personally I don't see the need for the split axle, I would just skim down the axle diameter slightly to fit. As the footplate is part of the chassis then using the underside of the footplate to add a couple of wiper pickups onto the top of the slaters wheels should be really easy to do.

And these very soft metal side rods.

I suspect you'll be fine with the rods, but if you wanted a replacement just clamp one rod to two layers of thin steel strip and use it as a drilling guide for the crankpin holes. An hour or so with a piercing saw and needle file will result in a nice set of steel rods.

 

[RichardG]

It does seem to be the case here.

I think we can see a few possible approaches, and none of them stands out as being the ideal:

1) Skim the backs of the HJ wheels and form new flanges
2) Drop Slater's wheels with modified axles into the existing chassis
3) Use Slater's wheels in a new chassis

The main challenges are:

a) The Heljan wheels are not orthogonal on their axles so they wobble a bit.
b) The Heljan wheelbase is not precisely 42 mm (6 scale feet) which rules out using a set of Premier rods except with a new chassis.
c) The final drive gear is not listed as a spare part, and will have to be drilled out to go onto a 3/16 inch axle (or procure a custom gear).
d) I cannot fathom out how the Heljan chassis is held together, but I do think dismantling will be a one-way process.

I am waiting for a decoder to arrive. See if this lets the model runs better or worse.

 

[adrian]

If it was mine I'd be going with option 2.

Ignore challenges a), b) and d) as no longer relevant. Challenge c) is still there as there only seems to be a thin slot for the gear, I would measure the gear and see if metal replacement available, if not then I'd get a thin steel washer, solder it to the axle in the right place and then a reamer through the gear wheel and pin the plastic gear to the steel washer to be a positive fixing.

Then new wiper pickups under the footplate onto the top of the wheels.

 

[RichardG]

pin the plastic gear to the steel washer to be a positive fixing.

Sounds like a plan.

I would have never thought of this on my own.

 

[Yorkshire Dave]

Sounds like a plan.

I would have never thought of this on my own.

That's what we're all here for - throwing ideas into the cauldron to provide a solution .

I'm guilty of becoming so involved with convention and minutiae and quite often stood back to think outside the box for what if? can I? unconventional solutions or even just return to basics and keep it simple.

 

[RichardG]

This seems like a good time to start doing some actual modelling. Let me see how this goes before I spend money on better wheels.

The handrails beside the front steps could be better. These are of plastic, fixed to the buffer beam but not the bottom step. I imagine, Heljan have done this to let the buffer beam be a removable subassembly. The handrails are too thick and to me they just look wrong.


This is an original handrail and an experimental replacement.


The new handrails are of nickel silver wire (diameter to match the brass wire handrails on the model) with top brackets drilled and cut from 1 mm square styrene. When I stick these on, the buffer beams will be fixed onto the model. I want to decide on the buffers before I do this.

The Heljan buffer heads are completely flat, while the photos I have found show buffers of the usual curved shape. Please, does anyone know of flat buffer heads like the Heljan ones? Perhaps on different classes of locos working in industry.

To make things easier, I want my model to be an unidentified ex-BR loco, now working in industry or possibly preserved. I’ll imagine it is one of the locos which was scrapped upon withdrawal from BR.

 

[Osgood]

Either:

1. Add drawing pin heads to provide a larger diameter convex face - an occasional industry mod. where tight radius operation required it.
Drill centre of buffer face to accommodate a short length of the drawing pin shank to give secure fastening.
Check out Borrows tank ICI Pilkington for a short wheelbase loco with big heads - about same proportions as the 02 (see pic below).

Or:
2. Paint and weather the buffer heads to simulate a curvature, which is often so shallow as to be almost invisible in many photos - in fact just putting a taper / radius on the outer edge might be enough to deceive the eye.

These buffers are barely convex - more flat than drawing pin, and easy to simulate the curvature by subtle shading:

 

[RichardG]

Thanks Tony. Painting let alone shading are not my forte, but I think this is the way to go instead of chancing another modification. Everything on this model is non standard compared to a kit, so for example the heads are plastic and knowing my luck probably an unglueable sort!

 

[PhilH]

​

Added on buffer faces - in this case on Bagnall 3207 at the Foxfield Railway. The larger dia. faces are fixed by 6 rivets (see buffer at rear), countersunk on the outside face.

Ignoring the white painted edge, buffer heads should have some "shading" to show the difference between the areas normally in or out of regular contact. In this case note the difference between the black area and the centre area, the centre being devoid of paint and slightly rusty (possibly not used recently). With an unpainted face in regular use the outside edge would probably be slightly rusty whereas the centre contact area would be more polished.

 

[RichardG]

I know what my starting point would be, I'd take the wheels off the axles, take 0.25mm off the back of each of them, then reprofile the flange.

Thanks for this Richard. I have had a correspondence with Heljan running for the last week or so, and we said our goodbyes yesterday.

Their representative happens to be a ScaleSeven modeller(!), and they suggested the amount of spare material available to be removed from the back of the tyre is 0.22 not 0.25 mm.

So for anyone reading this and intending to have a go, I suggest skim 0.2 mm. This will be the first step in creating a wheel which is compatible with ScaleSeven track, but is not a scale wheel in that the tyre will be too wide.

I am waiting for a LokPilot decoder to arrive. I want to see how well the model can run before I attempt anything mechanical.

 

[RichardG]

I am waiting for a decoder to arrive. See if this lets the model runs better or worse.

Like a fool I saw a second hand "ESU" decoder advertised on eBay and bought it. This turned out to be a Bachmann decoder made by ESU around 15 years ago. These decoders carry the letters ‘ESU’ on the circuit board and they are a first-generation LokPilot, suitably crippled by ESU to make sure they don't complete with their own product. Needless to say the performance was crap (the loco would barely start or stop) so this was returned for refund.

Buy cheap buy twice! I now have a brand new (and real) LokPilot 5.

This decoder has twelve (12) CVs associated with motor control, which would be a bit daunting were it not for ESU’s auto-tune feature. I have never seen one of these in action before. Essentially, you put the loco on a length of track long enough to let it run flat out in either direction for two seconds. Write the value 0 into CV54 and then press F1. The model runs and stops, and you then have a decoder configured for the characteristics of the motor.

I am quietly amazed. When I think of the hours I have spent setting up the decoders for my H0 locos, and never being quite sure I have got it right, this is a game-changer.

For completeness, I don't think the 470uF capacitor on the Heljan motherboard is providing any stay-alive capability beyond a tiny fraction of a second, but it isn't doing any harm either. ESU do a full-fat stay-alive module to pair with the LokPilot, but there isn't space to hide one of these inside the bonnet.

The Heljan 02 is running staggeringly well (though it was pretty good with ESUs factory settings) so I will put it aside to run it at NEEGOG on 11th July before beginning the conversion.


Decoder and packaging!

 

[Yorkshire Dave]

Like a fool I saw a second hand "ESU" decoder advertised on eBay and bought it. This turned out to be a Bachmann decoder made by ESU around 15 years ago. These decoders carry the letters ‘ESU’ on the circuit board and they are a first-generation LokPilot, suitably crippled by ESU to make sure they don't complete with their own product. Needless to say the performance was crap (the loco would barely start or stop) so this was returned for refund.

These are ESU v2 decoders and cannot be read by Lokprogrammer 3 or higher and as you've stated - a waste of time. Also it appears the vendor's description was not totally accurate. Yes, it is ESU but they should have also stated the generation as v2 and/or what loco it came from - assuming they knew. Personally I shy away from secondhand decoders unless I know their origin - which in my case are people I know.

This decoder has twelve (12) CVs associated with motor control, which would be a bit daunting were it not for ESU’s auto-tune feature. I have never seen one of these in action before. Essentially, you put the loco on a length of track long enough to let it run flat out in either direction for two seconds. Write the value 0 into CV54 and then press F1. The model runs and stops, and you then have a decoder configured for the characteristics of the motor.

I am quietly amazed. When I think of the hours I have spent setting up the decoders for my H0 locos, and never being quite sure I have got it right, this is a game-changer.

CV54=0, F1 is useful but find I still manually fine tune the decoder afterwards. I now start by using the recommended motor control settings suggested by ESU, see which one gives the best performance then manually fine tune from there. I've found you can use CV54 several times on the same decoder and get different motor parameter settings each time.

For completeness, I don't think the 470uF capacitor on the Heljan motherboard is providing any stay-alive capability beyond a tiny fraction of a second, but it isn't doing any harm either. ESU do a full-fat stay-alive module to pair with the LokPilot, but there isn't space to hide one of these inside the bonnet.

That's all it needs to do - provide enough current/power for several milliseconds to get over the hesitant spot. No need for a full-fat stay-alive and have the loco run on in its own length. I only install stay-alives in short wheelbase and shunting locos and take the view that they are completely unnecessary in longer wheelbase locos where the pick-ups are spread over more wheels. Should you decide install a 'beefier' stay-alive have a look at the compact versions offered by other manufacturers.

Decoder and packaging!

Packaging can be somewhat excessive nowadays. ESU have a few standard boxes for their decoders, however the Rails package is excessive. If it originated from overseas I can understand the larger box as there is less likelihood of it being lost/mislaid in the automated distribution centres. I usually purchase my decoders from Coastal DCC and they either use Jiffy Bags or a box just large enough for the ESU box.