How do I fit decoder to Rothery 0-4-0?

[Pasquin1971]

Hi - hoping someone can help. I’ve just bought the Rothery Industries 0-4-0 and want to fit an R8249 decoder. But I can’t see any place inside the loco where the decoder might attach. And haven’t found any guidance or videos on this. Can someone advise on how to fit the decoder to this kind of model?

[RDS]

@pasquin 1971

I have approved and rotated your image and also deleted the 2 extra duplicate threads you had raised. Please note that your pictures do not appear straight away and need moderator approval.

[Jim-R855]

I think for an R8249 you will need to do away with the front weight and secure the decoder in the smokebox where it will occupy the space that the weight takes up.

Smaller decoders are available from other manufacturers and you might find one that will fit into the curve of the boiler over the motor, or if you pop the coal out of the bunker you will find a small space there which you may be able to utilise (on my Tolgus Tin* that is full of resistors for LED loco lamps), or alternatively if you can find a really tiny decoder, the empty space behind the motor under the cab (which I think diesel 0-4-0s carry a second weight in, but not these little steam locos) may be of some use. Although it is not currently fitted as I have been using it to test other locos as I have converted them, I am able to fit a Zen mini 4fn decoder in the smokebox area by cutting the weight down to about half height. Given that 0-4-0s don't have many pickups, I may yet remove the weight altogether to add a stay alive board and capacitor. Of course, without any ballast I don't know how many wagons it will be able to pull.

*one of many locos that have used the same GWR 101 body with different livery over the years

[96RAF]

There were several specific guides in the DCC conversions page on this site, but they appear to be lost apart from the generic guide.

https://support.hornby.com/hc/en-gb/articles/360014216060-Decoder-Installation-Guides

You do not need to put any of the suppression kit back in place as it is not needed, suppression being taken care of by the decoder.

It is possible to fit a socket (4, 6 or 8-pin) to these generic chassis allowing for easy fitment of a decoder. Fitting a socket is just as much soldering work as hard-wiring the decoder as shown in the guides. Note my picture uses non standard wiring colours (blue and yellow motor wires should be orange and grey).

[ColinB]

This is how I did it on an 0-4-0 Caledonian. I wired in a 6 pin socket and then used a Zimo 6 pin decoder which is super small. The bit hanging down the side is the YouChoos Stay Alive circuit that also fits. I am sure it will fit even with the weight in place. The other advantage is the Zimo has a higher current rating that the Hornby, which is what I think this motor needs. THe two blobs at the bottom are the driver and fireman.

[RDS]

I don't have the same Loco but on one with the same sort of motor mounting and lack of space, I have used an installation similar to ColinB where I left the Decoder free to move slightly on its wires. I did however, use Heat Shrink tubing loosely fitted over the Decoder to prevent any shorting out.

[Pasquin1971]

Thanks all for the advice. I'm looking at that wiring diagram now and it sort of makes sense. I basically need to sit the decoder between the black wires that come up from the lower section and the motor from what I can see. I'll go step by step, and then I'll probably sit the decoder unit to the front. I'll see how I get on. Thanks again - really, none of this makes sense to a newbie without the advice on this forum.

[Brew Man]

The wires that come up from below should be black and red if it has original wiring. They go to the input of the decoder, then grey and pink wires from the decoder to the motor.

[Rog RJ]

@Brew Man

.........then grey and pink wires from the decoder to the motor.

 

 

Should be grey and orange, not grey and pink. Orange and grey are the standard decoder colours for motor connections.

[96RAF]

Also be aware Hornby tend to wire their locos using all black wires. Up to you if you standardise your colours or just wing it with what is already there.

[ColinB]

If you buy the 6 pin socket it comes with the right coloured wires so you ditch the Hornby wires and use the ones supplied with the socket.

[Fishmanoz]

Lots of detail on here, all correct but not quite to KISS standard for me. And there is room to fit the 8249 you want to use, with or without a socket and without removing weights.

The fitting is just a matter of:

• remove body
• unsolder both wires and the capacitor from the motor
• discard the capacitor
• solder existing wire from pickups on one side to decoder red, and from the other side to decoder black
• solder decoder orange and grey to motor connections
• place on DCC track and test on address 03
• if it runs the opposite way to what you were expecting, swap orange and grey on motor connections. Test again
• replace body and place on the programming track to change away from default 03 address to your preferred one, leaving 03 free to test your next new loco/installation.

If you want to use a socket, as is best practice, then wire the socket as above instead of the decoder. 8-pin socket for an 8249. only 4 pins used as there are no lights or other functions needed for an 0-4-0.

If you are unsure of the pins, look in the DCC section of this site under decoder installation and you’ll find the generic guide including pin detail as referred to by Rob (RAF) above.

[Brew Man]

@Rog(RJ)

Sorry, yes, grey and orange.