Having awful trouble converting a 'DCC Compatible' to DCC

[Will Hay]

I'm following the hornby guide to convert an R2675 to DCC.

I've never soldered before and after what I thought was successful practise I can't get the solder to do anything but drop off.

 

I'm at this point:

 

https://www.dropbox.com/s/xuspicyn3poe740/20200116_211154.jpg?dl=0

 

I now have one red and one black end and dont know where they go.

 

I know the double red end soldiers to the decoder red, and the double black soldiers to the decoder black.

 

I also know the orange and grey go to the capacitor lega but I have no idea where my red and black ends go to.

[Will Hay]

Ah, it seems that once wires are connected it works.

 

The loose wires I have should be loose.

[Chrissaf]

Regarding soldering....my 'How to Solder' tutorial might help.

https://www.hornby.com/uk-en/forum/how-to-solder-for-model-railways/?p=1/

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I can't get the solder to do anything but drop off.

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I would not be suprised to learn that you have gone for the cheapest solder you can find, which these days is the 'Lead Free' variety. Lead Free solder is notoriously dificult to use by a soldering newbie. My advice is to spend the extra cash and buy the far more expensive 60/40 Lead/Tin Multi-core solder. 60/40 is so much easier to use by a newbie. The Multi-core just means that the solder is formed as a tube and has flux inside it.

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Another reason for solder not sticking, is that the two things being soldered are not bright and shiny and freshly tinned. Solder will not stick to tarnished surfaces if no flux is used.

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This is all explained in more detail in my linked tutorial.

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[96RAF]

There should be no loose wires - red or black. These colours join the wheel pickups to the decoder track wires.

The mantra is - red and black to the track - orange and grey the other way (to the motor).

The only loose wires from the decoder should be blue, white, yellow, green and purple if present at the decoder. Insulate individually and stow these wires.

[Will Hay]

Thank you for the solder guide.

No, I didn't purposely choose the cheapest, it simply came with the pack.

 

RAF.

Righto, thank you, but in that case I have no idea why the thing is currently zooming around the track.

The two 'ends' are shown in my pic, I assume they're correct.

[Chrissaf]

I have no idea why the thing is currently zooming around the track.

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Yes, but is it controllable using your DCC controller? There might still be a connection from the wheels to the motor that you haven't broken.

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Before conversion, the wheel pickups go directly to the motor.

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This connection needs to be broken (removed) so that the decoder can be inserted electrically in the middle of the original wheel to motor circuit. Thus the decoder wiring actually replaces the existing wheel to motor wires.

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After conversion:

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The Decoder red & black wires go to the wheels and the Decoder orange & grey wires go to the motor. The Decoder now sits electrically in the centre of the loco with the wheels connected on one side of it and the motor connected on the other side of it.

[Fishmanoz]

And despite what the guide says, do not solder orange and grey to the capacitor legs, remove the capacitor (unsolder it's legs from the motor connectors) and anything else connected (sometimes there is more than one component connected here, sometimes not) and solder orange and grey directly to the motor connections.  These decoder wires should be the only connections to the motor.

 

The likely cause of zooming around out of control is called DC Runaway and happens when the decoder gets a corrupted DCC signal and thinks it's DC.  Causes are usually dirty rails, wheels (treads and backs) and/or poor tensioning of the pickups on the wheel backs. If your controller can program CVs, you can turn off DC Running in CV29 by adding 2 to the value currently written there. Irrespective, make sure everything is spotlessly clean and tensioned and see how you go.

 

Also note, decoders can become more sensitive to DC Runaway if they have been subjected to shorts on the track.

[Will Hay]

Thank you all.

 

When I say 'zooming around the track' that's because I make it so, at top speed.

 

It's responds perfectly to controller commands, both fast and slow.

 

"sometimes there is more than one component connected here, sometimes not"

 

This is key.

There is a black and red wires to the wheels, they're fine.

The additional red and black wires I'm referring to, those shown in the dropbox image, were soldered to the capacitor.