DCC Loco Conversions - 1 - DCC and Me

DCC a Marmite Technology

The "Realising My Dream" series of posts summarises the development of my personal railway, warts and all, but what about this new fangled tech called "DCC", fad, gimmick or maybe useful?

50 years on from my first childhood with most real world hassles out of the way I had dived back into model railways with relish, but how things had changed since I last enjoyed my trains back in the early 70s at the company railway club.

I still had all my locomotives and rolling stock from the 1970s that I intended to run, some of those were over 10 years old even then, some nearly as old as me.

The company railway club was long established and working to 4mm scale, OO gauge with all the track work hand built with code 100 rail on copper clad fibreglass sleepers. There was certainly some talent demonstrated crafting all the point work.

Stock was owned by the members and was mainly Hornby Dublo with some British Trix so Dublo/Trix couplings were the de-facto standard. At the time the Triang Mk3 hook and bar was current but was not liked for two reasons, one the size, and two the off centreline hooks would cause the front wagons in a long train of wagons (5-6ft) to crab significantly and aid derailments.

So all the stock I bought (including Wrenn, Airfix GMR, Palitoy Mainline and Hornby) I retrofitted to those couplings. Second hand Dublo and Trix was available from a local model shop which like many others faded away by the early noughties.

Along with my 2nd childhood a devil came onto the scene to extract cash from my wallet, eekBay and my modest collection of 'vintage' exploded with even more Dublo and British Trix, oh dear.

Now this was before I was able to build a layout anywhere, not for at least another 5 years, so they piled up in stackable Stollen cake trays from Lidl, thanks Lidl, great long term stock boxes!

DCC or not DCC?

Building the railway baseboards and supporting framework was very much independent of whether I continued with DC or migrated to DCC, it was only when committing to track laying and wiring a decision is required.

Having been a professional engineer I cast a critical eye over this "Only two wires" system.

This was probably the biggest dubious quality sales pitch statement since someone coined the phrase "The greatest thing since sliced bread". I hate pre-sliced bread, always too thin and goes stale quickly due to all the exposed surfaces, no problem, throw it away and buy more!

The only two wires earache has since been superseded by those selling expensive cars, "Self Drive", "Auto .. blah" etc. "oh but you still need to sit in the driver’s seat and stay fully alert with nothing to do but stare at the road and fall asleep".

Ok, back from my "One foot in the grave" semi-rant, (loved that show, I appreciate it even more as I become a Victor), off I go again, two wires eh?

Let's face it, if the non-techie public was told the truth it would be total gobbledegook, and besides for introductory layouts it only needed a few "Two wires", or in 'tech' speak "pairs of wires" and sales would not have been forthcoming. So I suppose they knew what they were doing.

Technically, system wise, yes, it is only two wires, basic operation is that all power and control is passed in an outgoing signal to the decoder and returns back to the source, hence the two wires.

Implementation however needs multiple pairs because in the real world we have joints in our rails and nickel silver has higher resistance than copper, giving the user the potential for intermittent connections and voltage drops on a well loaded system.

If you do run everything possible it will require a sound power distribution system to satisfy demand over the entire layout. This wasn't required so much in my DC days, it was a mix of controlled 12vDC for trains, 16vAC for points and uncontrolled 12vDC for other items such as lighting and signals.

The weakness of DCC is also its greatest strength, digital circuitry that responds quickly to demands but also to an interruption in the power supply which causes it to reboot when power is re-applied.

A momentary interruption of DC is not noticed as the motor continues as a flywheel keeps the loco rolling and carries on immediately power is restored.

Unfortunately the DCC components will shut down quickly, reboot and ramp up speed again based on your CV settings, if the interruption occurs again, it repeats the cycle.

The “only two wires” started the Marmite scenario over DCC and has been the cause of many heated debates, sorry, arguments with battle lines drawn, and casualties, those chucked off of groups or left in disgust.

Having worked on the large cab-control wired company club layout supporting up to 13 drivers the thought of even wiring a large layout with DC for even say, 4 driver cab-control with large inflexible control panels was daunting. A railway cannot evolve if that optimised control panel needs changing or all the section breaks are in the wrong place. Track sections too short for a long loco or too long for a short one is also irritating.

Concluding

So DCC is good for me because :-

1) I can drive and park any given loco anywhere,
2) I can really drive a double header,
3) I can really drive a banker,
4) My railway can evolve easily and readily.

My series of posts is not about whether you like Marmite, sorry, DCC or not, they are about the 'fun' I have had with locomotive decoding fitting over the last 9 years, and hope I can convey what you may be up against with models from different manufacturers over the last 50 years.

By all means tell me where I have gone wrong, could have done it better or different, or for me to explain in more detail, have a chuckle at what may seem masochistic, or any questions whatsoever, but please don't try and convince me that DC is better than DCC, Rule 1 applies.

Decoder fittings I will cover is for driving locos only, I do not use DCC for sound or accessories. However I will include many pre-DCC, those so called "DCC Ready" horrors and on through to those which need small machine tools to modify e.g. Hornby Dublo integrated motors which I have yet to tackle.

Next: Before I get on with the conversions I'll outline my general approach, techniques and tools, useful and not so useful.

Jim

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Image: Hornby Dublo Stanier 8F

 

Hi Paul, thanks.

I would consider re-magnetising if possible as direct replacement of the magnet with a NEO type can be counterproductive, it will certainly improve torque above the original as new and reduce the current consumption but it can make running far less smooth at low speeds, it is possible to have too strong a magnet, which causes cogging at low speed.

Some I have upgraded with NEO and been good, others poor, having bought a magnetiser a few years ago I opt for a re-mag first.

Admittedly this is more of an issue with tank engines for shunting as opposed to the larger heavy locomotives used at speed, but don't throw away the original magnet in case you decide to revert.

Jim

 

Which is how many a Dublo loco ended up with a burnt out armature, when it's that bad it cannot be used anyway, but when it's half way there the armature burns. It's curious I have had some locos with magnets intact after 40 years, confirmed by low current draw, others die quickly, even without disassembly, surprised a Wrenn has had that problem.

I have had the odd Triang magnet fail, but that is rare too.

Jim

 

Hi Keith.

I've no experience with sound or Lais loco decoders but can wholeheartedly agree with what you say on other the issues which match my findings after fitting decoders to a large quantity and variety of locos, especially those that were manufactured decades before DCC.

It can also be quite shocking how bad some so called DCC ready locos are for fitting and performance on DCC and how amazingly good some vintage locos can be with very little work.

The Dublo 8F in the image was a simple conversion being a non-Ringfield and despite only 4 wheel pickup is an excellent performer on DCC which encourages me to convert two other Ringfield motored 8Fs which will be more of a challenge.

Jim

 

Hi Keith, that conversion seems quite popular but I have not really found that the all or nothing motion has been an issue, but then again many of my Lima diesel locomotives and railcars have had a significant increases in weight to compensate for wheel changes eliminating rubber tyred wheelsets, (rubber tyres are a pet hate, if I can dispense with them I will, filthy things). The extra weight in the spacious loco bodies tames them somewhat.

If it wasn't that Heljan's build quality has been so awful for the price I would have bought their Class 25, 33 etc rather than spend a lot of time on making the Lima models into decent DCC runners, their lack of detail doesn't bother me, probably 1/3rd of my loco fleet are 'antique' many with motor back ends on the footplate!

Some of the old Triang, Triang-Hornby and Hornby, 3 different eras of design IMO of pre-DCC relied a lot on the early magnet grip on steel rails and later rubber tyres and need a similar ballast load in their bodies for decent grip on my gradients, similarly it tames them and enhances pickup efficiency between rail and wheels.

Certainly the all or nothing has been present in recent 0-4-0 and 0-6-0 'cheapies' but then again they are probably aimed at kiddies train set racetracks, likewise basic Bachmann and Hornby fitted decoders.

Jim

 

Unlike the 1960s Scalextric cars of my childhood which had a variant of the sturdy X04.

The only plus of these tiny motors is that many more smaller locos were possible, and even larger ones had their footplates freed of motor back ends, no longer crewed by a mutilated driver and fireman.

Mind you the move away from basic 3 pole armatures certainly improved slow running, but who needs that in a starter set.