4 Pin or 8 Pin when converting to DCC

[Will Hay]

I'm increasing my stock by, in my main, buying 'DCC compatible' trains and converting them to DCC.

To date I've been buying Hornby 8 pin recorders and cutting off the socket but recently I put a 4 pin decoder into an old 0-6-0 shunter, which appears fine.

 

My question questions is this...

 

...is there anything stopping me using a 4 pin decoder on a larger train, a Class 47 for example?

 

I have a 4 pin in a 0-6-0 team engine I plan to retire, in favour of an 'arriving immently' diesel.

 

Thanks.

Rob/willhay555 

 

[Howbi]

The Hornby 4 pin decoder is the same as the 6 pin & 8 pin apart from the number of wires connecting.......the disadvantage of the 4 pin is that you have no functions such as lights.......but if that is not an issue then by all means use the 4 pin........however, it is better to future proof the conversion by soldering in to the loco an 8 pin socket so that any variety of 8 pin decoder can be installed including sound and lights..........HB

[96RAF]

If your skill set allows it you can always solder direct to the decoder pads if you want to add functions later regardless of how many pins it starts out with 4 or 8.

 

6 pin decoders tend to have part of their circuitry for function power built into the loco PCB.

[Will Hay]

Thank you.

[ColinB]

I use a combination of 8 and 6 pin DCC sockets when converting my old locos. I always use a socket as it makes it easy to revert bact to DC if there is an issue with the loco. It also allows you to change between different types of decoder. I didn't even know they did 4 pin. If you want lights or extra features like smoke box glow or cab lights, then 8 pin is better as the VCC supply for the lights appears on a pin. As previously said with a 4 or 6 pin, you either have to create your own or solder directly to the decoder (never a good idea). I did find that some of the 6 pin decoders that were meant for N gauge got damaged when trying to drive an old Bachmann Jubilee loco (I chose them for their size), but I think that was an issue with current limit.

[Ruffnut Thorston]

There's also 21 pin sockets... 😉

 

Not to mention the other, more recent variations!

 

The four pin decoder is a Hornby speciality, and is mainly used in the 0-6-0 "Jinty" chassis models...

[Will Hay]

One final question on this subject.

I have a DCC ready Class 58 coming and I have another 4 pin decoder spare from yet another 0-6-0 that's going to sit in a siding and not run.

Can I use the 4Pin on the Class 58 i.e. by way of an adapter perhaps?

I'm just trying to avoid the additional cost of another 8Pin decoder.

[96RAF]

You could make up an 8 to 4 pin adapter using NEM652 plug/socket (below) hard wiring your 4 pin decoder plug via short wires to the correct (4 corner) holes.

/media/tinymce_upload/534f3e59bbdb9c0dbba414cf532cf1b4.JPG

[Will Hay]

Perfect.

Thank you.

 

Silly me, I do have an eight pin plate or two sat around I've previously cut off the hornby decoders for my dcc upgrades, I guess I could just create an '8 pin' from that.

How do ascertain which of the four wires go to which corner?

Thanks again.

[Howbi]

Will..........this is the wire colours pattern for the eight pin socket or plug..........HB

/media/tinymce_upload/a413720669fecfe5deba9a24a6c702ba.png

[Will Hay]

Superb, thank you howbiman.

[Will Hay]

I've soldered my four pin to what I believe is the dummy eight pin that comes with a 'dcc ready' train.

 

Is there any reason why this wouldn't work?

It doesn't.

 

https://www.dropbox.com/s/rhtkuyopofzu1gf/20200302_204636.jpg?dl=0

 

Thanks.

Rob

[Howbi]

That definitely will not work because the blanking plate is a mini circuit board........pins 1, 8 & 2 are joined and pins 4,5 & 6 are joined.......this is to conduct current from the pick-up wires to the motor and lights when in DC mode.........you may have destroyed the decoder..........had not realised that this was your intention to solder to the blanking plate.......thought you were connecting the 4 pin decoder to a surplus 8 pin plug with harness still attached..........HB

[Will Hay]

Yeah, I was, but I couldn't find it.

No matter.

My soldering skills were superb <what with being a half full kinda guy>.

[96RAF]

This is what a blanking plug does, even though you can’t see it on your version.

Hence by soldering on the decoder wires as you did you just shorted the motor and track wires together at each end.

/media/tinymce_upload/2dd1cc894bdbcd3f57eccdf16d84ea7f.JPG

[ColinB]

The thing I find really interesting, when I am converting old locos to DCC I generally use a Hornby 8 pin DCC socket. I used to work in electronics so I know about PCBs. Basically the PCB is an eight pin socket that comes out to holes on the PCB. If you search the Hornby parts suppliers, I have found so far that there are at least 4 different part numbers for the part and the price varies from about £1.50 to £6.60+ for basically the same part. I don't know if Hornby have a patent on the PCB, but I am surprised some Chinese firm is not supplying them for £1.00 seeing as you can get a fully populated relay board for not much more, and they are generally better quality as they use "plated hole" technology.