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SBasic Question....(sorry)


60 posts

For Xmas my Family have clubbed together and bought me a Hornby R3805 Class 5MT.

They tell me it is DCC ready....

Basically, how difficult is it to fit a Hornby decoder (or other make) and what is involved please?


Roger   (Chalford)


1629 posts

It is not a basic question. Anway on this model the DCC decoder is in the tender. So you read the maintenance manual that comes with the loco and it will tell you how to get the tender body off. I did mine but I can't remember if it is one screw or two. Normally you unscrew the screws (you will need a small philips/posidrive head screwdriver) and pull the tender top either forwards or backwards (again in the instructions). Once the tender lid is off at the back of the tender you will see a rectangular socket with 8 pins. Into this there will be an 8 pin header, bit like in your PC, if you have ever opened it. Remove this header, and put the decoder header in its place. The decoder should have something to indicate pin 1, as will the socket, so make sure pin 1 goes to pin 1.If it is a Hornby decoder you will need to insulate the decoder by placing it in a bit of heat shrink, or a plastic sleeve of some kind, if you use some other manufacturer it should come ready sleeved. Now just put the tender back together and you are done. It usually takes longer to get the tender lid off without damaging it, than fitting the decoder.

I forgot to mention, you need an 8 pin decoder.


12437 posts

Community Moderator

Just to add, on an 8 pin decoder plug. If there is no Pin 1 indicator, then the Orange wire goes to Pin 1.

Chris........ Making the wood in the trees visible.


751 posts

Do you actually have a dcc layout to run it on?


60 posts

Hi All,

Thanks for that info...  does,nt sound too bad.

As it will be an Xmas present, I have not seen the loco or the paperwork yet..

and, yes I do  have a DCC layout  (all hornby + Select ) but have not progressed past setting the locos address!!  rather nervous of locking up 

the controller or decoder by entering the wrong keystrokes!!


Roger  (Chalford)


1629 posts

It isn't you just have to be careful. As I say getting the tender top is usually the most difficult bit. Just take your time and don't be in a rush. Just make sure the decoder is insulated, there is a lot of metal in the tender for it to short out against. Oh, and buy one of those tools for removing the 4 pin lead. If you are going to take the tender apart it is a good idea to separate it from the loco, to avoid one of those 4 pin wires breaking.


2 posts

Having read this, I have a DCC ready loco but having removed the blank connector there is no indocator at all which way the chip should be inserted - a 1 would have been a great clue. Any ideas how to proceed without frying everything?


410 posts


Having read this, I have a DCC ready loco but having removed the blank connector there is no indocator at all which way the chip should be inserted - a 1 would have been a great clue. Any ideas how to proceed without frying everything?

Basically you will not fry anything.if you insert a 8 pin decoder the wrong way .you will have worked out there are only two ways .it makes no difference to the motor only to the lighting .


14226 posts

Community Moderator

Pin 1 will usually have some sort of indicator either a 1, a star or a triangle.

Halton Brat - Running Win 10, 64-bit - RM (Pro-Pack) with Elite as Controller-A, Select as Walkabout and E-Link as Controller-B - Locos are mostly TTS. http://www.halton96th.org.uk/robs_rails.html


1629 posts

As Jane says on this loco it doesn't really matter if you get it round the wrong way. On diesels or locos with lights if you get the connector round the wrong way the lights won't work, but it won't damage anything. The only thing is the controller says forward you loco will go backwards and vice versa,  if you get the connector round the wrong way. Most of the time though you probably won't notice. I must admit unless it is a diesel and I can't see a marker for pin 1, then I just insert and hope for the best. You can run the loco with the tender lid off, so you can check it against your other locos. If you are going to turn the header round, make sure all the power is off.

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