DCC Track Power using Select Controller

[SeanG]

Hello All,

I am putting together a large corner layout powered from a Select controller. 

To power all the track I fitted 2 x point clips to all points (10 points in total). 

The Select controller now displays message EO when power is selected on with no functionality. 

Any suggestions as to why this has happened and any solutions would be greatly received.

[walkingthedog]

It means you have a short circuit somewhere. Are you using Hornby points? A track diagram would help. 

[Chrissaf]

A corner layout design could potentially offer the possibility of creating a 'reverse loop'. A 'reverse loop' will create an instant 'short circuit' when DCC point clips are fitted to all the points. The EO display on the Select is indicating "Emergency Off" which is the Select 'short circuit' error message when using a Select with either 1.6 or 2.0 firmware.

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I define a 'reverse loop' as a track layout scenario where any route taken through the layout by a loco, ends up with the loco arriving back at its original starting point, but facing in the opposite direction. This would include a route via a Turntable.

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Draw a sketch of your track layout design and it can then be assessed for the presence of any 'reverse loops' that might be present and how to resolve them. You could use the definition described in the paragraph above to assess your own layout for the presence of a 'reverse loop' in the absence of posting an image.

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Read TIP 8 in my 'Forum Tips' page (see link below) that describes how to post an image.

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Note the following though. Hornby approve images, not moderators and Hornby shut up shop at 3pm UK time of a Friday, so any image you post tomorrow may not appear until Monday.

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TIP: As a newbie poster on the forum, just be aware that the 'Blue Button with the White Arrow' is not a 'Reply to this post' button. If you want to reply to any of the posts, scroll down and write your reply in the reply text box at the bottom of the page and click the Green 'Reply' button.

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See also – further TIPs on how to get the best user experience from this forum.

https://www.hornby.com/uk-en/forum/tips-on-using-the-forum/

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[SeanG]

Thanks for such a fast response!

Yes all components are Hornby. 

I have replicated Hornbys Large corner layout track layout. All elements are in place except the turntable. 

Below is a screenshot of the track layout. Hopefully that is detailed enough for your assessment. 

Thanks again. /media/tinymce_upload/566bf97fce41b657322664d309931d8c.png

[SeanG]

Hi All,

Thanks for your responses. I have posted a picture but it's not showing yet as I believe images need to be moderated.

You can see the layout by searching for R7277  on Hornby site or Large Corner Layout on the internet.

Description is as follows:

An extremely novel idea combining an end to end layout which is surrounded by two long running continuous main line loops.  The layout allows easy access to all parts as it is of a wrap-around construction.

A terminus station is located at each end of the layout, both of which are accessed from either main line at completely different points.  The lower left hand terminus station has an extensive locomotive depot plus a turntable.  The top right hand terminus station has a large goods yard with sidings that are of sufficient length to stable complete trains.

The layout provides potential for multiple train operations such as continual use of the outside loops combined with busy shunting duties.

This layout is suitable for either analogue or digital control. 

 I can see how this lauout can lead to a short but what can I do to prevent this and get full functionality from the layout?

 

Thanks again

[Flashbang]

Is this the plan?

/media/tinymce_upload/3762245b554ea5f670c124d0d49c4e50.jpg

 

[Chrissaf]

This R7277 track product has been discussed before. This is an example where Hornby Marketing have come up with an idea, but have not had technical engineers assessing the technical issues of what Marketing are bringing to the market. Note also that Hornby Marketing have completely failed to advise that the R070 TT in the plan needs to be modified for DCC use as out of the box it is configured for DC Analogue.

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This 'short circuit' issue can be relatively easy to correct on a DCC Digital layout. To rub 'salt into the wound' Hornby have made the R8238 DCC Digital Reverse Loop Module (RLM) obsolete, so if no old stock of the R8238 can be found, then a non Hornby brand of RLM will need to be sourced. This in itself is not a major problem as many brands of RLM are available and will work. However, there is a caveat to this which I will discuss near the end of this reply.

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That Hornby R7277 Large Corner layout design when wired 'all live' for a DCC operating layout is full of multiple short circuit generating 'reverse loops' the track pieces indicated in black are the pieces that create the 'reverse loops'.

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/media/tinymce_upload/629f07ddc2caabc4cc8b73de96f88026.jpg

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The most effective way to resolve this problem is to install four RLMs. You will need to wire the DCC power connections to the main central track area as a double loop 'Dog Bone' layout see Page 23 in my downloadable tutorial.....see further below.

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The actual final position of the Insulated Rail Joiners need to be just a little further apart on the end loops than the longest train (loco plus rolling stock) that you intend to run on the layout. The sections of track protected by the RLMs must be electrically isolated from the rest of the layout, hence the indicative IRJ positions indicated by the thick red bars across the track.

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/media/tinymce_upload/30347c74d48a037c4b6d46e3e836eb57.jpg

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Now to the caveat, the standard Select power supply is 1 amp. Therefore you need an RLM that is able to detect 'short circuits' with a trigger current that is less than 1 amp, not all brands can. This can make some brands of RLM ineffective if they cannot support adjustable trigger currents less than 1 amp. The best option to provide reliable RLM operation would be to upgrade the Select 1 amp power supply to the Hornby P9300 4 amp Digital power supply.

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As to brands and 'pros and cons' of some of the RLMs available on the market that can be used to replace the now obsolete Hornby R8238 RLM, have a read of my downloadable 'Reverse Loop Tutorial' (Chapter 7) which can be downloaded from here. Reading this downloadable tutorial document should also make understanding my reply in this thread easier.

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https://btcloud.bt.com/web/app/share/invite/TVjeV58CqN

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TIP: As this is your very first posted question, just be aware that the 'Blue Button with the White Arrow' is not a 'Reply to this post' button. If you want to reply to any of the posts, scroll down and write your reply in the reply text box at the bottom of the page and click the Green 'Reply' button.

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Particularly as my reply includes an image. If you use the blue button, any reply you write, may be held back for image approval. Even though it is already a previously published image.

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See also – further TIPs on how to get the best user experience from this forum.

https://www.hornby.com/uk-en/forum/tips-on-using-the-forum/

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[96RAF]

This is the track in question and as Chris will soon highlight to show it has reverse loops, but Hornby in their infinite wisdom have neglected to mention this and that for DC use you will require manual polarity switching or for DCC use a Reverse Loop Module (RLM).

/media/tinymce_upload/4e6dffbadaf898e3476ddf492ecd3ce7.JPG

[walkingthedog]

Does it have reverse loops. Looks like them but they don't seem to go back on themselves. 

[walkingthedog]

Every time I try and use a reverse loop I either end up in a siding or go off somewhere else. Surely they must have built this layout.

[walkingthedog]

I still can't see the reverse loops. Not saying they're not there. I would have thought Hornby would have made and tested this layout first. 

[Chrissaf]

Does it have reverse loops. Looks like them but they don't seem to go back on themselves.

...&...

I still can't see the reverse loops. Not saying they're not there. I would have thought Hornby would have made and tested this layout first.

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Most definitely has RLs. More than one, but I will explain just one of them in isolation as an example. All the different RL possibilities are explained in depth in my downloadable tutorial. Reverse loops do not have to be just the basic 'tear drop' shape you are thinking of.

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Remember that the definition of a RL is ANY route that allows a loco to arrive back at its starting point but facing the other way.

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In the drawing below, the white arrow represents a loco showing which way the front is facing as it traverses through the points from starting 'Position 1' to finish 'Position 10'.

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If all the points are live because DCC point clips have been fitted, then the route through the points (even if a convoluted route as per my drawing) will cross-over the rail phase (polarity) and create a short circuit.

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/media/tinymce_upload/138e638a57c3a4148efae5d953aca3e9.jpg

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EDIT: To help with the understanding of the above drawing:

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You have to consider the Reverse Loop puzzle from the rail polarity (which is termed phase in DCC) point of view.

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If you start at 'Position 1' with your finger on the OUTSIDE rail and then follow the arrowed path with your finger. Always keeping your finger on the SAME rail. Then when your finger reaches 'Position 10' it will now be on the INSIDE rail of the loop. This is a short circuit of the inner to outer rail on the track.

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[Chrissaf]

I would have thought Hornby would have made and tested this layout first.

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Apparently not......when this R7277 pack was released. Rob fed back the Reverse Loop issue via his in-house Hornby technical contacts. They in turn passed the issue up the Hornby management tree. The feedback Rob got was that this issue had not been noticed during the pre-launch stage and that perhaps the previously discontinued R8238 RLM module should now be re-instated. I maybe over stepping the mark by mentioning this info so don't be surprised if this post should suddenly disappear.

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Rob and I have been waiting patiently for a real user who has purchased the R7277 to raise a question about 'short circuits', we guessed one (and probably more) would materialise sooner or later. This thread is the first.

[walkingthedog]

Thanks. I now understand. A reverse loop it isn't but it has the same effect. 

[96RAF]

You can pick up this topic on other the forums because as is usual the same question has been asked in several places. Usually the answers they get turn out to agree with each other.

Often we never get to find out what the end result Is on either forum.

 

There is also FB to watch as I have found many questions we have already answered on here that are being asked over there.  I briefly answer and refer posters to look back over here. A recent question was how do I load the drivers for eLink on a Win 10 device. First answer was wrong in that it advised him to load RM first, then plug in the eLink and set the correct com port. The place abounds with flaky advice and of course the trolls have no charity for fools who get both barrels normally.

[Fishmanoz]

Beg to differ WTD. A bit like walking and talking like a duck, it is definitely an RL.  As said, it's more than just a simple teardrop. As per Chris's definition, if you can follow the track in any fashion and return to the starting point facing the opposite way, it's an RL.  And you can here, from both loops at both ends.

 

You might also ask why 4 RLs need to be considered, can't you just have one?  The answer is that for any RL, it must have an isolated section longer than the longest train in use but also not allow more than one train to enter or leave it at the same time. So you can have an isolated section that covers all the reversing possibilities, but it will include a large part of the layout and so allow multiple trains entering or leaving at the same time under basic operations with more than one train on the layout.  So not practical if you want to use the capability of this layout. 

[walkingthedog]

Yes I realise that Fishy. I just couldn't pick it out amongst the far too much track. 

[96RAF]

I will be keen to see the solution as I think the multiple places in the points system where polarity can be swapped  will make it too complex to achieve. Maybe needing individual frog-juicer type RLMs at each point, but that doesn’t get us the long isolated section Fishy points out.

 

Likely to be repeated at the other end but different.

[Chrissaf]

Rob, look more closely at my solution on page 1. All possible 'short circuit' eventualities are catered for in my solution with four simple RLM sections on the ends of the loops. It is in essence a near copy of my fully described & documented solution in my PDF tutorial shown on Page 29

[96RAF]

I see. All due to the curves which will become the isolated sections, hence 4 x RLMs.

If you take off the curved tracks at each end and straighten out the corner you get a nice end to end layout.

[Chrissaf]

Exactly.... 😎

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It then doesn't matter how complicated the middle 'end to end' section becomes, the end loop RLM sections will always resolve any possible short circuits that can conceivably be created. With the exception of the R070 Hornby TurnTable that will generate its own 'short circuits' if not modified for DCC working as per the link I provided in my initial reply.

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All that is then necessary is to keep the power connections to the middle 'end to end' section 100% polarity (phase) consistent. Top rail to top rail and bottom rail to bottom rail when looking at the middle 'end to end' section (logically) as being a straight horizontal set of tracks. Get one of those connections crossed, and you get an instant short circuit on the middle 'end to end' section that the RLMs cannot resolve.

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PS - I would not want to provide a DC Analogue power distribution solution for that track plan if asked.

[96RAF]

I understand the R8238:is currently out of production and no further orders are expected to be made. You may find a few lurking in model shop listings. Other than that you will have to source an alternative device from another manufacturer. You may wish to compare solid state devices against mechanical relay devices for reaction time and reliability as well as failure mode.

[Chrissaf]

Rob, and others.

Just to recap...... in my original reply. I gave a link for my downloadable reverse loop tutorial. As I also said in my original reply..... Chapter 7 compares a range of different brands of 'Reverse Loop Modules' that will help to identify and choose an alternative brand and model to the discontinued Hornby R8238.