jhk

[NickNack32]

[96RAF]

There has been a lot of discussion on here about how to convert a turntable to dcc operation, Hornby has posted their method on this site and others have done it slightly differently. Do a search on the forum for turntable.

 

You will need a locomotive decoder to control it. The R8247 accessory decoder is NOT used for the task as the output is not suitable.

[Chrissaf]

As RAF says, the R8247 is not suitable to operate a TT, you use a loco decoder such as for example the Hornby R8249.

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This conversion is not the method recommended by forum members ie the removal of the rail contact strips. Members recommend using Insulated Rail Joiners (IRJ) instead to create the required track isolation. But the method in the link below is good for the decoder and wiring bit of the conversion to DCC operation. Your RailMaster & eLink (info from your other post) includes a TT option in the 'Track Plan' feature / function. This feature works with the R8249 decoder when used on a TT.

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I would never just rely on twisting wires together and taping them up. Solder and heat shrink or use terminal strips if can't solder. Unlike the points wiring in your previous post, the decoder used to operate a TT has a much lower current requirement. Any wire of a similar thickness to those used on the decoder pre-wired tails will do for making the final connection. The track side (DCC in) of the decoder could connect to the same terminal strip used for the R8247s that I included in the supporting drawing of my reply to your previous post.

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Which by the way. I see that this post mentions your previous post requesting information that you have yet to give any indication that you have read the replies. It is just basic common courtesy and politeness to reply to forum members replies if only to acknowledge that you have read them. If you create a reputation over time of not at least acknowledging members replies, you may end up having your requests ignored too. If you don't know how to reply to an existing post. You just scroll down to the bottom of the page containing the post (you have to be logged in to your account) and put your acknowledgement in the big empty reply text box and click the green reply button.

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 https://www.hornby.com/uk-en/hornby-dcc/decoder-installation-guides/turntable-conversion

[NickNack32]

[NickNack32]

[NickNack32]

[Chrissaf]

There are quite a few TurnTable (TT) related you-tube videos...click link below to see a list of them....however, none of them are (in my opinion) particularly comprehensive and detailed. Some are just downright mis-leading as well. But by all means have a look at them if you will. My honest opinion is that after watching some of these you-tube videos you will be even more confused about what is required to do the conversion. The ones I have watched lead me to believe that they are 'the blind leading the blind', the presenters making these videos really haven't got a clue. Plus the fact that the videos in this list, don't really go into the wiring aspect of the conversion. They just tend to focus on demonstrating the TT after conversion. But as far as I know, these are all the videos specifically relating to the Hornby TT that are available.

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https://www.youtube.com/results?search_query=hornby+turntable+dcc

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Rather than the videos. I recommend reading the TT article on this web site instead.

http://www.brian-lambert.co.uk/DCC%202.html#Turntables

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Regarding:

.....because I can't understand the instructional web link you gave me.

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In all honesty and with the greatest respect, if you are struggling to understand the page I gave you the link for, then you are going to struggle to do the conversion. Those instructions are the simplest I have ever seen. Not necessarily the best instructions from a method perspective, but they are the simplest.

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The problem with TT's in a DCC environment is that they create 'short circuits' and you need to know how to modify the TT to remove the risk of the short circuit happening (this is something that the you-tube videos just don't seem to go into and explain). The Hornby TT is designed for a DC layout, not DCC. In a DC layout, the power to the track is turned off when a loco is being turned on it. Thus, when there is a 'short' as the TT turns (the short is inevitable as it is an inherent part of the Hornby TT design) it doesn't matter because there is no power connected to the track part of it to react to the short. In DCC, the track is live all the time, thus the part of the TT design that generates the short has to be modified to eliminate it happening. A short in a DCC layout will cause the DCC controller to shut off.

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The TT 'Short Circuit' phenomenon and the modifications needed to eliminate them are described in the 'Brian Lambert' (second link) web page I gave you. If you find that you cannot understand Brian's web page descriptions then you really are going to struggle. Brian's page describes two modification options. The first one is for TT's that do not have a 'split ring'. The second documented modification is for TT's that do have 'split rings' such as the Hornby R070 TurnTable.

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For information and just for the purpose of providing some guidance as you are a forum Newbie. The 'white arrow in the blue box' embedded in each post is not a 'click this to reply' button. It is a 'quote this post' button. There are very few times when it is necessary to quote a post, particularly long ones like I tend to write. As I explained in my earlier reply, the preferred method of replying is to use the 'Reply' text box and Green 'Reply' button at the bottom of the page.

[DigitalBlue]

You can use the R8247 to control a turntable and not have to resort to soldering irons and pulling your turntable apart if you don't want to  😀

 

There are a few drawbacks:

 

• You must have an Elite or eLink, the Select can't program the CV's to make it work.
• You can't use the older R8246
• The turntable will only move in one direction
• You can't vary the speed, so it you find it too noisy in standard mode, it'll still be noisy!
• All the issues around DCC polarity still apply, this only controls the turntable motor!

 

You will have to cut the plugs off of the brown and black wires as they won't fit into the accessory decoder terminals. (Hornby: if you want plug & play you could make them big enough to fit standard accessory plug ends!) If you don't want to do this then you'll need to make up some sort of connector with perhaps connector strips to get some wires to push into the accessory decoder. 

 

The first step is to choose the output you want to use on the decoder. You then need to decide if you want to 'pulse' the output to move the turntable one track at a time, or have a continuous output that keeps going until you stop it. 

 

If you want to pulse the output you need to determine roughly how long the motor needs to be on for. You then programme the number of tenths of a second into the appropriate CV value. So, if you choose output 1, and want the motor to run for ten seconds, then program value 100 into CV number 515 with the decoder connected to your programming track. Alternatively use value 0 for CV number 515 which will keep a constant output going. You then press the controller button once to start, and again to stop when required. 

 

Once programmed, to connect the turntable, connect the black wire to terminal 'C' and the brown wire to either + or - depending on which controller wheel you want to use to move the turntable. On an Elite, connecting to plus means control wheel one does all the work, minus means control wheel two. If you want to reverse the direction of the turntable, connect brown to C and the black wire to either + or - as above. 

 

You then select the programmed accessory number, and press the controller to fire up the motor. If you chose pulse mode then the motor stops after the programmed duration. If you set the CV to 0 for continuous output, then to stop the motor press the opposite control wheel. 

 

I don't doubt that this is not the best way to control the turntable as you can't vary the speed, or choose the direction it rotates in, but, you can control your turntable without having to modify it (assuming you wire up via some strip connector blocks) which may be easier for some, or for more temporary setups. 

 

If you combine this with the turntable providing power to outlet tracks rather than having them DCC powered all the time, then IMO operation is relatively simple, and solder iron free. 

 

Like I say, maybe not the ideal solution but hopefully will help those who don't want to fit a loco decoder to their turntable, and want to keep connections simple. 

[Yelrow]

Digital blue,thats very informative, and novel, , but for me,if you have Railmaster, its so much easier, to give TT, a loco number, and click on track plan to move in either direction. john

[Fishmanoz]

DB, echoing John in part, I can see that your method will work, but can see very little reason for doing it this way. I realise you acknowledge it isn't the best way, in fact I would suggest that its inflexibility pretty much rules it out.

 

You say it can be done this way without modifying the turntable.  I agree with a loco decoder it is a little more difficult to attach it, but still easily solved with any type of screwed terminal block to connect the decoder motor orange and grey wires to the TT motor and track power to red and black.  Hardly a difficult "modification".  Connecting an 8247 may be simpler but you still have the issue of programming the correct pulse length or continuous operation of the decoder output port.

 

The real modification needed for the TT though is the one to avoid shorts on rotation and phase reversal at half the outlet tracks.  These problems are still present whether you use an 8247, 8249 or just power the motor with DC and still need one of the previously documented methods to overcome them.

 

In short, yes you can use an 8247 to power the bridge on the Hornby TT, but I suggest you don't. 

[96RAF]

The reason you cant use the older R8216 acc decoder is that it is a pulse only output, no way to make it a continuous output.

[DigitalBlue]

Well, as I said, I'm not saying it's the best option, but it is an option. Often it's simply stated that you can't use the accessory decoder to drive the turntable motor under DCC control. 

 

My view is that it's up to the individual to chose what's best for them, some prefer to learn through trying the different options, others will be happy to take advice and go the decoder router. I think it's better that they're all documented and available so people can make that choice.  😆

[St1ngr4y]

I would guess that another limitation of the R8247 method is that the maximum run time would be 25.5 seconds, since the maximum value of the CV is 255.

Ray

[DigitalBlue]

CV value of 0 means the current stays on until you stop it...

[mjb1961]

Hi ,,,the method I use is the HORNBY one ,I run it via a R8249 loco decoder tucked away inside the little hut and run it from my dcc CONTROLER ,a NCE powercab ,I don't use ,elink ,elite or railmaster ,the only problem with the HORNBY method is a change in polarity at some point as the turntable rotates which for me means any loco with sound playing whilst on the bridge turns off when entering this area although it does not short out the CONTROLER ( I had to switch wires around on one of the exit tracks ,putting + to - and - to + it that makes sense ) other than that it is great ,,I have read somewhere on here or another forum that a HORNBY reverse loop module could be used to fix the problem of reverse polarity and the sound turning off ,I've yet to try this ,,,

[Chrissaf]

I have read somewhere on here or another forum that a HORNBY reverse loop module could be used to fix the problem of reverse polarity and the sound turning off ,I've yet to try this.

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That won't work on the Hornby TT. The Hornby TT uses a 'Split Ring' to perform a reversal of the bridge rails when the TT goes through 180 degrees. The way that the 'Split Ring' is designed, there is a gap in it, that mechanically removes power from the TT bridge just as it transits between the two rail polarities. The only way you could keep the sound going during the designed in break in track power, would be to fit a large value 'stay alive' capacitor to the decoder to maintain power during the short transition power break. Some physical surgery to the TT may possibly be able to convert it to a 'Slip Ring' design, then the RLM solution would work.