How to convert a J94 to DCC

If you spend any time on social media in groups for railway modellers, you'll find people asking for someone to fit chips to their newly-purchased locomotives. I’m a novice at this but wondered how hard it could be. After all, when a model is marked “DCC Ready”, it's already fitted with a socket isn't it?

Handed a DJM J94, it turns out that all we have to do is remove the blanking plug and insert the new chip. Yes, you need to make sure you have the right new chip, but most suppliers will be able to advise on this. It's important to insert pin 1 in the correct way around too, but the pin is marked and so is the socket.

So simple is this task, that we had plenty of time to personalise the model. A quick look online (type 68012 J94 into a search engine) and we found some prototype photos and even a little history.

68012 ran on the Cromford and High Peak Railway in the mid-1960s. The crews became fed up with the rain blowing into the cab and made themselves some wooden shutters to keep it out. Modifications like this were pretty common on locomotives in industry but rarer on BR lines. It's quite eye-catching, though, and easy to model.

All locomotives should have a crew (an empty cab looks so strange), and finding one that fitted was actually harder than converting to DCC.

Finally, a little dirt completes the model. It's now a little different from the way it came out of the box, all for a couple of evenings’ effort.

Shopping List

DJM

OO gauge Hunslet J94 

Digitrains

860013 6-pin decoder 

Monty's Models

MSV2 – Locomotive crew

Humbrol

Weathering powder – Dark Earth and Smoke 

1

Does any manufacturer offer easier access to the DCC socket than DJM? In common with the other steam locomotives from the firm, the smokebox door is held in place with a couple of high-strength magnets. Pull it away and inside you find the socket on long wires so it can be carefully pulled out.

2

To fit a decoder chip, the blanking plate is eased out of the holder. The chip is then fitted, taking care to put pin one, show on the instructions, into the correct end of the socket. Numbers for this are marked on the board. The long wires are for a slay-alive capacitor but can be tucked into the body if you aren't fitting one.

3

There's not a lot of height in the cab so it's important to check your crew fits inside before you go to the bother of painting them.

4

A set of white metal crew from Monty's Models are a much better fit, although they do need to stand toward the middle of the cab where this is a little more height. Since they will be largely hidden, we gave them a quick coat of paint followed by a wash of shading ink. Sticking their feet to a lolly stick with superglue makes the job easier.

5

68012 was a Cromford and High Peak engine and in some prototype photos sported a pair of wooden shutters at the front of the cab to protect the crew from the weather. A couple of pieces of 0.5mm thick Plastikard, 9 by 11mm, scribed and painted to look like wood replicate this. The fittings were pretty crude in real life so it's important not to be too neat when modelling for a change.

6

To cover the plastic coal, the real stuff is crushed and then fixed with watered-down PVA. Looking at prototype photos, there was often a pile on the back of the roof, presumably from careless work with a digger when loading up. It probably didn’t survive long once the loco was running, but it might be fun to replicate.

7

Another prototype touch is a lamp on the front buffer beam. None is included with the loco so we found a set of Hornby accessories. The lamp on the bunker has its lens painted red. If you are keen, these can be fitted with Blu-Tak so they can be removed as required, but these are permanently fixed with superglue.

8

Although the model is supplied weathered, we added a bit more grot using weathering powders. Around the smokebox, there's usually a lot of rust where the heat has burnt off the paint, and ash from cleaning out the tubes. As well as colour, these have texture so you need powder rather than paint to model it.

9

Where the crew clambers around their machine, the paint will wear away and the steel shines through. Dry-brushing areas such as steps and handrails with Humbrol Metalcote gunmetal just bring a little shine to them. A little rust might be appropriate if your crews aren't active enough to keep the metal polished.

Do you need to seal weathering powders on the model?

Most powders are sticky enough when applied to matt paint to cling on pretty well. The J94 paint is quite smooth so for a really filthy locomotive, a coat of matt varnish before weathering might be a good idea. After that though, leave it alone.

If you handle the model enough to wear the powder away, the first areas to come clean will be the same as those on the prototype that would be washed by the rain anyway, so the result can look even more realistic.

Another issue is that the colour of the weathering will change if you spray it with varnish or fixative, possibly ruining your work.

More advice

Confused by technical terms – 'DC' or 'DCC'? Here's everything you need to know about these two methods of control.  

Considering software to help control your DCC model railway? Our guide explains how software can help improve operation. 

Need more information about DCC? Find more advice and best practice in our dedicated section.