Fitting DCC to really old Locos

[David-1212374]

Can anyone help please. I have a few old Class 37's that are basic but I would like to make them able to run on my new digital track. It looks like I need to add the pin connection before I add the chip. Can anyone help please

[Chrissaf]

There are different types of Digital DCC decoder sockets to suit different types of decoder. There are 21 pin sockets and also 4 & 6 pin ones as well as others. Hornby currently use 8 pin sockets, so that is what I will focus on in this reply.

You can buy pre-wired 8 pin sockets on ebay to make installation easier.

8 pin pre-wired dcc sockets | eBay

Then the schematic below shows an example of how it is wired into your loco. The LED & resistor lighting circuits are purely optional. The schematic is drawn for a Hornby R8249 decoder, but any branded 8 pin decoder will be suitable.

Soldering skills will be required to perform this loco modification.

FAQ - How To Solder for Model Railways.

You have used the term 'really old locos'. Old locos draw a lot more current than modern ones and can damage basic decoders that do not have enough current handling capacity. Before modification you need to perform a 'stall test' to determine the current specification required to source a suitable brand of decoder. Hornby decoders are only rated at 500mA continuous. Old motors typically need a decoder rated at 1 amp continuous current draw.

Brian Lambert's 'Stall Test' guide

Your Class 37 might have 'Ringfield' motors [you need to identify the actual fitted motor type as each type of motor has its own DCC upgrade challenges]. If your motors are 'Ringfields', then there are more than one type of Ringfield and you need to identify which variant you have so that you can follow the appropriate upgrade methodology. See this link for details of the various Ringfield motor types.

Brian Lambert's Decoder Install Page [scroll down for Ringfield]

[Going Spare]

The original Hornby class 37 was fitted with a twin-worm motor, for which I think it is accepted the standard R8249 decoder does not have the capability to handle.

[96RAF]

If it is essentially like this one then it is more of a challenge to convert than a ring-field type and will need a heftier decoder as GS says.

[Going Spare]

Not quite like that. H-D used something akin to a Ringfield motor in their 'Deltic'. The Tri-ang Hornby Class 37 employed a X04-derived motor as per Service Sheet 45.

[Yelrow]

David, these old locos, must run Perfectly, on DC, before you attempt, the clever stuff. If they dont, forget the idea.

[The son of Triangman]

Service Sheet 45. Class 37

[The son of Triangman]

As Yelrow rightly says the loco will need to be a very good runner as DCC will show up every fault. You will need a decoder that can take a stall current of at least 1 Amp.

[The son of Triangman]

The Tri-ang hymek has a similar power unit. Conversion is quite easy, but don't solder directly to the motor brushes or you will never get them out when it comes time to change them.

[The son of Triangman]

Service sheet 69.

[The son of Triangman]

Service sheet 92

Sheet 92A

[ColinB]

There was a guy on EBay that was selling 1.6 to 2 amp DCC capable decoders. Zimo also do a very high current one.