How to plug a chip into a Bachmann K3

[George-351466]

My Bachmann K3 is a first generation DCC ready Bachmann model (32-275) with an 8 pin socket in the loco body. But space there is practically non existent and I’m going to have to extent the chip harness and fit the decoder, speaker and power bank in the tender.

That will require some drilling and carefully routing of cables, but two questions arise:

1. I’m assuming I only need the 4 strands on the harness which deal with the pick-ups and can cut off the remainder, so as to minimise the bundle of wires between loco and tender. Correct?
2. The DCC socket in the loco has no indication that I can see, as to which way round the decoder plug should be attached: ie, no little 1 marked on the board. Does it matter which way round it goes (I’m assuming it does); is trial and error a valid method, or will I damage the chip by testing it wrongly?

So far, my later Bachmann locos have taken to their Hornby Bluetooth decoders perfectly, but they’ve been 22 pin versions in tenders - actually easier fits than to some Hornby locos. However, K3 is obviously earlier, but a loco that I dearly want to add to my stock of HM7000 runners.

Thanks for any advice you can offer.

[SteveM6]

Although I am not familiar with the Bachmann K3 could the decoder be tucked into the smokebox? That’s an area often overlooked.

perfectly feasible to extend just four wires - orange, grey, red and black for power supply and the motor. Bear in mind you will need a very thin flexible wire for this.

Rather than chop the decoder harness, could you consider relocating the decoder socket to the tender?

[Britannia Builder]

I have a Bachmann 3MT Tank, which appears from photos to have a smaller diameter smokebox than the K3, and I fitted both the decoder and the smallest speaker in the smokebox, with the power bank in the cab. On my Hornby Peppercorn A1 (Tornado lookalike) I fitted decoder, speaker and power bank in the smokebox.

Regards, John

[George-351466]

Thanks for the replies. Unfortunately, the smoke box is solid metal, so no room there. In fact the firebox moulding in the cab is also metal which makes drilling through there a little more awkward. These two weights make the loco nice and heavy though.

Relocating the socket into the tender sounds like a good option and I’ll look again at that, but which way do I plug the decoder into it?

[Going Spare]

I am not a DCC user so apologies if my comments are off the mark but my thoughts were to move the decoder socket from the loco to the tender so that you have just 4 thin wires running between the loco and decoder socket, 2 from the loco pick-ups and 2 returning to the motor.

The LNER group standard tender gives a reasonable void and the removable coal moulding gives a degree of access from above.

[WilliamDavid]

I’ve made that modification, and variations of it, on many a loco when fitting sound.

[SteveM6]

Relocating the socket into the tender sounds like a good option and I’ll look again at that, but which way do I plug the decoder into it?

 

 

If you put it in the wrong way it not hurt but will run backwards. Just follow the wires - red and black to track, orange and grey the other way (to the motor).

[Brew Man]

Just look at the colours of the wires on the existing socket connections. The orange wire is pin 1.

[George-351466]

Many thanks again I’ve now got a clear path towards making the modification. Great assistance from the Forum 👍🏻