Class 50 DCC connector

[ColinB]

I have just bought a secondhand class 50. I notice it has the normal DCC 8 pin socket plus a 4 pin socket alongside it. On the one I bought it was already fitted with a DCC decoder and there is nothing in the 4 pin socket. On another one I have just bought which is currently set at dc there is combined 8 and 4 pin header in the two sockets. I have also noticed the top lights work on the DC version, but not on the DCC version. Before I start pulling things apart to find the fault, does anyone know what the 4 pin socket actually does and should there be something in there when running DCC. I have downloaded the maintenance sheet and it does not even mention the 4 pin connector, just a 21 pin and a 8 pin.

[96RAF]

Discrete socket or integrated into a PCB ??

 

Trace its connections back Colin. It may be for a stay alive (2-pins) or body to chassis connection for in body lights (4-pins) or who knows what.

 

Buying S/H you have to be prepared for anything strange that Johnny Bodger has installed.

[Rog RJ]

I have a cl50 with the 8+4 sockets too.  Mine was bought new with 8 pin and 4 pin blankng plugs.  Converted to DCC by removing both blanking plugs and just fitting an R8249 decoder.  There are no "top lights" fitted in mine but the lights that are fitted work correctly.

 

I can't remember if there were any instructions concerning the 4 pin plug.

[ColinB]

Yes, all my lights work except the top lights. The easy option is to take the 12 pin out of the DC version and put it into the DCC version to see if the top lights suddenly work and do likewise with the DCC decoder, it was just easier if someone knew what the 4 pin connector did. I hate taking these things apart, you breathe on them too heavy and something falls off. I have to fit a DCC decoder to the DC one so I will do it then. 

[LMSFan72]

The 4-pin socket doesn't do anything on DCC - it seems to be another motor connection as I recall from tracing it. The top lights switch with the headlights. The light boards are common negative but they have separate positive connections. From recollection. The top light +ve is the red wire on the RH connector viewed as if you are the driver. The top lights are built into the body and connected by contact pads that connect with the sprung contacts on the back of the light boards at the cab end of the chassis. It's most likely that it's the connection there that's the problem unless the top light positive wires are disconnected/poorly connected at both ends. I have found that if the body is not fully clipped down those top lights don't work because the connection is not made properly. Also check continuity on the wiring. If the headlight works (I just realised that I am assuming that you have the top headcode light AND the headlight on the "nose" on your model) then it's very unlikely to be the board/decoder socket.

 

EDIT: I have just found my trace of the main PCB so have posted that but it will need moderating

[LMSFan72]

This is the trace for the PCB marked 1621-X0091R which sounds like the one in question. I have traces of others too, but, they don't have the additional 4-pin

/media/tinymce_upload/2c90192464bd7584c5a14e5a57666753.png

[ColinB]

Great thank you LMSFan72. I will do some more checking now i know what I am looking for, it will be a lot easier. Yes, all the other lights work, it is just the ones in the headcode, which as you say are in the body. It is a pain because I can't test them with the body off.

[LMSFan72]

I would use a 9v battery with a 1K resisitor and  touch the contacts underneath the cab to check the LEDs (they hang below the cab floor and face forward). The positive is the RH one as if you were sat in the drivers seat. 

[96RAF]

This should help in the meantime. The 8+4 sockets are plain to see.

http://s374444733.websitehome.co.uk/class-50/index.htm

 

... further up the listing page is fitting sound late ron into the same model.

[ColinB]

Eventually found it, it was the copper connectors that connect to the pcbs in the body, thay weren't pulled out far enough, so I assume they weren't making a contact.