Turntable help [DCC Layout]

[Chrissaf]

My son has a DCC trainset, but am normal analog turntable, struggling to work out how it all fits together, does the turntable need to be run off a separate controller? 

[Chrissaf]

This is a common question that comes up regularly, as a result a dedicated 'How to DCC the R070 TT' post and thread has been created......you can read it here:

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As you say the TT is analogue (assuming the hornby R070 TT), before you get to the 'How do I control it' answer, you first have to modify the TT for DCC operation else it generates a 'short circuit' on a DCC powered layout.

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The posts below also document the 'how do you control it' options.

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R070 Turn Table DCC Modification

http://www.hornby.com/uk-en/forum/r070-hornby-turn-table-to-dcc-including-images/?p=1

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Additionally, if using RailMaster, which your posting history indicates.

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R070 Setting Up configuration in RailMaster

http://www.hornby.com/uk-en/forum/r070-turntable-configuration-in-railmaster/?p=1

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R070 DCC Conversion – my version with a detailed drawing

https://www.hornby.com/uk-en/forum/post/view/topic_id/27722/?p=2

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[nikibmx01]

I live in Fareham, have bought the parts a decoder, but whilst I have electronics knowledge I'm not confident doing this, is there anyone that could do the first part of adding the decoder to the turntable for me please. 

[nikibmx01]

Chrissaf, going to do this today. just so I'm sure the orange and grey go to the bit in the photo and the black and red go where?  Is that to the black and brown wires?

how do we connect to the track? 

[Chrissaf]

It's a good job you raised this question. Because I have just reviewed my original reply that I gave and realised (not that anybody else picked up on it) that I advised incorrect information. I have now removed my earlier post to prevent giving someone else the same bad info.

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The wires I highlighted in my earlier reply to remove, actually relate to the main DCC conversion of the Hornby R070 TT to prevent 'short circuits' when the TT bridge rotates.

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The Decoder being used to operate the motor that rotates the TT bridge connects to the two wires in the image below ... sorry for the incorrect previous guidance.

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/media/tinymce_upload/357a5c4ed77e5f9c65c430465b6a731f.jpg

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The two wires in the photo above go to the electric motor used to drive the TT bridge.

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The Orange and Grey from the decoder connects to those two wires shown all coiled up. The Black and Red wires of the Decoder go to anywhere where it is easy and convenient to connect to your DCC Controller track supply. Whether that be the track itself via a R8242 DCC power clip (X8011 crimp terminals needed to make the connection). Or just Teed into the wires that go between your DCC Controller track output and the track.

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The Red & Black wires can go either way round, it doesn't matter. Reverse the Orange & Grey wires if the TT bridge rotates in the wrong direction. Although it doesn't really matter, convention would say that 'Forward' on the controller would equate to the TT bridge rotating 'clockwise'. Reverse on the controller anti-clockwise. But at the end of day it really isn't that important and is personal choice.

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/media/tinymce_upload/f98f1c59965dcd11b60d6cf477942bb4.jpg

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This image has been reproduced (pasted) from the bottom link in my previous reply above. Review this other previous link for the details. This image is reproduced to show that the TT bridge wires (the disconnected ones) are different wires to the motor wires going to the decoder.

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EDIT: Although I replied to your post within 17 minutes. Given the nature of your post and my answer I am a bit concerned that after several hours passing, you have not acknowledged seeing it. If you go ahead and wire it as per my original reply (now removed) there is potential for the decoder to be damaged.

 

[nikibmx01]

Sorry I have seen it still not been brave enough to attempt. I still don't get it, I get connecting the motor but not the track and the droppers I'm going to re read the other links. 

[nikibmx01]

/media/tinymce_upload/5673973e7a090e4f789204482a6f43f1.jpg

[nikibmx01]

What do I use from above photo. 

[Chrissaf]

Regarding the image in my last reply above. Let me try to explain in simple terms the information it is trying to convey. I am sorry, but I cannot make it any more simpler than the description below:

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In general, unless a turntable is designed & marketed specifically as a DCC friendly turntable it may need to have some form of modification to prevent 'short circuits' from tripping the DCC controller as the TT Bridge rotates.

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What I am about to describe is not an issue on a DC Analogue layout as the track power is turned down to zero on a DC Analogue controller when the TT bridge rotates.

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DCC track power however is 'always live', thus the rails on the TT bridge will be live also. The tracks on the inlets and outlet tracks will also be live.

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As the Hornby R070 TT bridge rotates, the bridge rails make contact with the inlet / outlet tracks, and rails of opposite DCC phase (polarity) will touch and generate a short. The image below demonstrates this.

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/media/tinymce_upload/6bc4616e44da84704c2926cb68e57439.jpg

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To prevent the 'short circuits' the rails on the Hornby R070 TT Bridge need to be isolated from the rails of the inlet and outlet tracks. There are a number of ways this can be done, but the method favoured by the consensus of the forum, is to use 'Insulated Rail Joiners' [ IRJs ]. The IRJs are indicated by the red dots on the earlier drawing.

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But installing IRJs adds another conundrum to be resolved. The IRJs prevent the power on the TT bridge rails from being transferred onto the outlet rails that the R070 TT Bridge aligns to as it rotates. This means that you then cannot drive the loco off of the R070 TT Bridge into the outlet siding (as the outlet siding has no power).

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This is where the blue and brown DCC power wires (termed a BUS in the drawing) come into play. These wires provide DCC track power from the controller to the outlet siding tracks that have been isolated by the inclusion of the IRJs.

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But now adding the additional DCC power wiring indicated by the brown and blue wires adds a further conundrum. The way that the Hornby R070 TT is physically constructed means that the rail polarity of the bridge rails reverses after the bridge has rotated 180° of a full 360° rotation. The point where this bridge rail reversal takes place is indicated by the 'dotted line' drawn on the R070 TT Bridge in my drawing.

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Thus the final jigsaw piece shown in the drawing is the reversal of the brown and blue power wires shown on the outlet tracks on each side of the 'dotted line'.

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Notice how the tracks on the right of the 'dotted line' have the left hand rail connected to the blue wire. But the outlet tracks on the left of the 'dotted line' have the left hand rail connected to the brown wire. Thus the power connection wiring on the tracks to the left of the dotted line are reversed compared to the tracks on the right of the dotted line. This wiring reversal cancels out the reversal that is produced by the TT Bridge rotation. This DCC track power wiring reversal is needed to eliminate the possibility of a 'short circuit' occurring.

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The use of Brown & Blue in my drawings have no significance. I just chose the colours at random to indicate the different phase (polarity) of the DCC power connections. Note: DC track voltages have polarity, DCC track voltage is Bi-polar and has phase, not polarity. But the polarity term is easier for some to understand.

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Read this reply whilst referring the text in this post to the image in my last reply. Then apply this information, when you re-read my post in the third linked post in my original reply. It should all then make perfect sense (hopefully).

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Just a reminder. This is a very long post and includes an image. Do not use the 'Blue Button' else your reply will disappear. Write any reply in the 'Reply Text box' at the bottom of the page and use the Green 'Reply' button.

[Chrissaf]

• The Turntable obviously.
• The decoder.
• Possibly the track power clip as long as it is a DCC friendly one [R8242] ... If it is an Analogue DC one [R602] it will need to be modified for DCC use by removing the suppression capacitor ... see photo below.
• You won't need the yellow switch or the turquoise wire.

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/media/tinymce_upload/61b827f3566c705a3036f23bd0f9f1f8.jpg

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You will also need a Soldering Iron and 60/40 Lead / Tin solder (best to avoid the cheaper lead free solder).

[nikibmx01]

Roght i have finally taken the plunge, i have done the above i did use the turquiose wires to connect to the track with the power clip. i decided to do the simple version of setting up like a loco, but it does not find the chip when i try to read the cv's. What have i done wrong!!!

[Chrissaf]

Your posting history indicates that you are using RailMaster, presumably with an eLink.

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The wires that you have attached the decoder red & black wires to, need to be connected to the 'PROG A& B' terminals of the controller in order to configure the decoder address. Although not ideal, you could achieve this by plugging your TT decoder track power clip into your 'programming track'. Personally, I would prefer a direct wired connection from the decoder to the controller 'PROG A&B' terminals. Although you are using the decoder on a Turntable which is an accessory, you pretend the decoder is being used as a locomotive for programming purposes.

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You only connect the decoder to the main layout track with the power clip. After it has been programmed with the address you want to give it on the 'PROG A&B' controller output

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With the decoder connected to the 'PROG A&B' terminals as indicated above.

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Open RailMaster and open the 'Loco Settings' screen. Do not try to call up or load any locos on this screen.

Go straight to the CV reading / writing screen by clicking the " i " icon. See image below ... red arrow:

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The CV Reading / Writing screen should open ... see image below.

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Your screen at this stage should be blank and not have any fields populated with data. Although technically you could, I suggest that you do not click the Read CVs Green tick at this stage.

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/media/tinymce_upload/36d9e74e1db876099c72cfcd58d09fa2.jpg

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In the CV1 value box (top red arrow) enter the DCC Address you want to give your 'Turntable' decoder. The CV1 value in this instance must be a value between 001 and 127. If you want a DCC Address value above 127 then a different addressing method must be performed.

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Then click the 'Pen' icon (bottom red arrow) to write that value to CV1. If successful, RailMaster should read back the value and show it in the CV1 value box.

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If that 'read back' action is successful, then click the bottom right red cross to exit the screen, then close the 'Loco Settings' screen.

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If all is well, you should now be able to now connect the decoder power clip to the main track and control the Turntable rotation using the DCC address you have just configured.

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On page 1 of this thread, I provided this link below, regarding instructions on how to configure RailMaster to control your Turntable.

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R070 Setting Up configuration in RailMaster

http://www.hornby.com/uk-en/forum/r070-turntable-configuration-in-railmaster/?p=1

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[nikibmx01]

Thank you so much for your help, I done it but we have one small issue. when the turntable turns past the feed track the copper connections cause a short and stops everything working, how can I sort this please. 

we don't have constant power to the track/turntable. 

[Chrissaf]

Go back to my very first reply to you on Page 1 of this thread.

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In that first reply of mine, click on the first clickable link. This takes you to a 'step by step' guide for making the Hornby TT DCC friendly.

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Read the contents of that first clickable link, in conjunction with the contents of my third clickable link in the same Page 1 reply. The third link is basically my version of the first link that was written by committee.

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My later reply on Page 1 timestamped at 16:36 explains how the 'short circuit' is created.

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Everything you need to know to resolve this 'short circuit' issue is covered on Page 1 of this thread, either directly in the replies themselves or via following clickable links in those replies.

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we don't have constant power to the track/turntable.

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If there was no power to the track and turntable bridge, then you wouldn't get a 'short circuit'. For you to have a 'short circuit' and for everything to shut down, then you must have power on the track and TT bridge track`.

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In case there is some confusion. The power to the TT bridge motor via the decoder which you have just finished installing is a completely different electrical circuit and has absolutely no involvement with creating the short on the track.

[nikibmx01]

right im on this again, but what is a IRJ? is it a part i can order?

Sorry about all the questions, but i am new to this and trying to sort for my boy.

[Rog RJ]

Insulated Rail Joiner.  Also known as insulating fishplates.   Every model shop will have some, either made by Hornby, Peco or other makers.  Hornby part number R920. Also available on eBay.

[Chrissaf]

IRJ = Insulated Rail Joiner.

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If the track is Hornby track, then IRJs are Hornby stock code R920 which is a pack of 12 individual IRJs [two joiners required for each track join, one for each rail]. They are basically a plastic equivalent of the normal metal track joiners.

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/media/tinymce_upload/48ca1c99a9f76171ec72a852cd4e7937.jpg

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Rog, posted whilst I was finding an image to post with my text.

[nikibmx01]

How do i connect the wires to these tracks

Thanks again guys

[Chrissaf]

Soldering is the best method. Outside side edge of track that is already laid, or underside of the rails if the wires are soldered on before laying. Just not on the inside of the track rail, as this rail area needs to be left clear for the wheel flanges.

[nikibmx01]

Brilliant thanks