8 Pin decoder Purple wire loose

[Stephen in Kerry]

I have just started fitting my first DCC decoder, and have noticed that a purple wire is disconnected at one end.

It's a Hornby decoder and it was like this out of the packet. Does anyone know if this faulty? Thanks for any help.

[96RAF]

No its fine. The decoder has nine wires but only an eight pin plug so the fourth function purple wire is a flying lead to connect to whatever function you want it to operate, else tape it over to insulate against short.

Also insulate the decoder either by a single layer of sellotape or similar on the decoder or insulate the metal bits of the loco/tender with tape.

[Stephen in Kerry]

@96RAF Thanks Rob, I've now got it working on a short programming track (as explained by @Chrissaf). I cut away the compression capacitor, and it's working fine - as far as I can tell on such a short track.

I tried to isolate the decoder from the body, but my double-sided tape wouldn't stick. I'll try again with insulating tape. Hornby (apparently) say not to cover the decoder itself in tape as it can get too warm.

Another snag I've hit so far is that the tender won't couple to the loco. There is a long thin post attached to the loco, and the holes in the tender coupling are too wide for it. There doesn't seem to be a flat screw in the box.

[Going Spare]

The drawbar just slips over the post on the loco chassis, I don't think there is any need for a screw.

[Stephen in Kerry]

Thanks @Going Spare. Considered that, but the drawbar won't stay up when the loco is stationary, and I'm struggling to see how to keep it from falling on the track.

Also, the post is grooved to take a mini flat-head screw driver, and it will unscrew, presumably to be replaced with another screw.

The instructions also show 2 similar screws on the loco and tender - the loco one is there, the tender has the post. Very puzzling.

[96RAF]

Edit: Following sight of further i formation none of the following applies but it is left for i formation of others who may have these types of coupling.

Sounds to me like the loco and tender do not match.

This is the post and clamp arrangement. The tender has a post and the loco drawbar has a clamp and springy fingers thing to pass current.

The other non powered drawbar is attached to the tender usually by a screw but can be built in and to the loco by a screw. Power is passed by way of a 4-wire plug (loco) and socket (tender).

[Howbi]

The screw holding the drawbar on the tender may need tightening to hold it horizontally, it can be tight but still free to swivel.

[Going Spare]

Service Sheet 366C appears to cover your loco. This shows the plastic drawbar screwed to the tender but no corresponding screw at the loco end, hence my earlier post. Have you tried releasing the tender screw to see whether it can hold the drawbar more tightly in position? The loco probably comes with a detailing pack in a small plastic bag secreted somewhere in the packaging: this might just include a screw. If you can't resolve the problem, I would suggest you seek advice from Customer Services.

[96RAF]

The maintenance sheet provided with the loco shows it clearly.

[Stephen in Kerry]

Thanks for the help (again) everyone. @96RAF, Rob I don't think the springy fingers things apply here, as there doesn't seem to be an electrical connection between loco and tender.

This is the 'close coupling' section from the sheet that came with it. They definitely seem to be flat head screws - and there is only one (which was on the loco). The post in your drawing was on the tender, but there is no way that it will hold the drawbar.

I'm tempted to find a replacement screw but I can hear the groans of abject horror even now!

[96RAF]

Yes there seem to be variations on the coupling drawbar theme.

If the screw is not illustrated and/or identified on the associated spares sheet then it may come as part of the small parts pack.

[Stephen in Kerry]

@96RAF, Rob I definitely can't see it. The only items in the spares packs are brake rods and metal versions of the badges, which are transferred on at the moment. I can't see how I would replace them. The small screw I found in my tool box should work.

[ColinB]

Have you tried unscrewing the dawbar from the tender and turning it round, I found sometimes one of the holes in the drawbar is bigger than the other.

[Stephen in Kerry]

@ColinB, yes I did try that, if anything it was wider (or certainly the same as the first hole).