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Offline Michael4  
#1 Posted : 09 December 2017 18:29:14(UTC)
Michael4

United Kingdom   
Joined: 02/02/2017(UTC)
Posts: 637
Location: England, South Coast
It took me a while to work this one out...

This is about getting yellow wires mixed, ie lighting of devices. Analogue of course...

If you make the mistake of powering the light on one signal from one transformer and the light on another linked signal from another transformer, things short.

Similarly, if you try and connect turnouts whose lights are powered by one transformer to switch tracks that are linked to signals powered by another transformer the same thing happens.

It is not a big deal but I don't really understand why it happens. I had hoped to use one transformer to power all lit devices, I now realise that I need to use one transformer per track.

So now I have:

Trafo 1 outer track catenary
Trafo 2 outer track track plus devices
Trafo 3 inner track catenary
Trafo 4 inner track track plus devices
(Trafo 5 upper track track no catenary)

My switch tracks, signals, turnouts etc are only working on track power and not catenary. I have not yet got my head around using switch tracks with catenary but fear that things will go wrong because I will be mixing power from two sources.

Am I making sense? Do I understand what I am doing? The answer to both is probably no but any advice much appreciated.
Offline H0  
#2 Posted : 09 December 2017 19:57:17(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 15,254
Location: DE-NW
Originally Posted by: Michael4 Go to Quoted Post
If you make the mistake of powering the light on one signal from one transformer and the light on another linked signal from another transformer, things short.
Says who?

Originally Posted by: Michael4 Go to Quoted Post
Similarly, if you try and connect turnouts whose lights are powered by one transformer to switch tracks that are linked to signals powered by another transformer the same thing happens.
Says who?

Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
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Offline Markus Schild  
#3 Posted : 09 December 2017 20:10:59(UTC)
Markus Schild

Germany   
Joined: 14/01/2006(UTC)
Posts: 1,802
Location: Wurttemberg
Hi Michael,

Did you check the polarity of transformers?
No, you must not mix power from two sources. But you can use several sources on the same layout. This means that only the brown side can be connected to two or more transformers. But not the yellow side. Every transformer must have its own, exclusive yellow harness.

Regards

Markus

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Offline H0  
#4 Posted : 09 December 2017 20:15:29(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 15,254
Location: DE-NW
Originally Posted by: Markus Schild Go to Quoted Post
Did you check the polarity of transformers?
With respect to accessories:
The polarity does not matter when you wire things correctly.
When polarity matters then the wiring is dangerously wrong.

Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
UserPostedImage
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Offline Michael4  
#5 Posted : 10 December 2017 10:17:24(UTC)
Michael4

United Kingdom   
Joined: 02/02/2017(UTC)
Posts: 637
Location: England, South Coast
Originally Posted by: Markus Schild Go to Quoted Post
Hi Michael,

Did you check the polarity of transformers?
No, you must not mix power from two sources. But you can use several sources on the same layout. This means that only the brown side can be connected to two or more transformers. But not the yellow side. Every transformer must have its own, exclusive yellow harness.

Regards

Markus



Thanks, this is what I finally worked out for myself and yes, it is obvious when I think about it. Turnouts, signals etc that are linked together in some way must get their 'yellow' from the same source.

Some months ago I wired all the turnouts on the layout together to one trafo to get their lights to function. I now need to split them up by track circuit.

This is my mistake but at least nothing is screwed down and I have yet to take the wiring under the board.

One learns...slowly!
Offline Robert Davies  
#6 Posted : 10 December 2017 17:18:50(UTC)
Robert Davies

United Kingdom   
Joined: 20/11/2010(UTC)
Posts: 426
Location: Worcestershire, UK
Originally Posted by: Michael4 Go to Quoted Post

Some months ago I wired all the turnouts on the layout together to one trafo to get their lights to function.

What's wrong with that? That should be fine provided that you do not have your yellows and browns crossed. As Tom (H0) said, if doing that causes a short it suggests that something is wrong somewhere else and you need to find that.
Robert
Era III - IV
2 x Central Station 2 v.2 (60214 + 60215)
Hardware versions 3.6 / 4.33
Software version 4.2.1 (0)
Offline dominator  
#7 Posted : 11 December 2017 03:16:16(UTC)
dominator

New Zealand   
Joined: 20/01/2015(UTC)
Posts: 1,195
Location: Kerikeri
I use one tranny to power all my points and uncouplers. The others control the locos. I used the same earth return on all of them though.
I recommend you do the same.

Dereck
Northland. NZ REMEMBER 0228 for ä
Offline GLI  
#8 Posted : 11 December 2017 05:09:55(UTC)
GLI


Joined: 28/02/2011(UTC)
Posts: 82
Location: Lithgow NSW Australia
I suffered this problem when using two transformers for my Marklin as a teenager nearly 50 years ago. The short circuit was caused by the two transformers being out of phase with each other.

The solution was simple: reverse the brown and red wires in one of the transformers. Once I did this, the problem went away.

Geoff
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Offline cookee_nz  
#9 Posted : 11 December 2017 05:46:18(UTC)
cookee_nz

New Zealand   
Joined: 31/12/2010(UTC)
Posts: 3,948
Location: Paremata, Wellington
Originally Posted by: H0 Go to Quoted Post
Originally Posted by: Markus Schild Go to Quoted Post
Did you check the polarity of transformers?
With respect to accessories:
The polarity does not matter when you wire things correctly.
When polarity matters then the wiring is dangerously wrong.



With respect Tom, this is only partly correct.

You can have a simple, fully correct simple layout of two ovals connected by turnouts but isolated from each other at the turnout so that both ovals can be controlled independently by two Trafos but Loco's can still cross from one oval to the other. The ovals are isolated by placing an insulator between the third rail at the transition turnouts.

This operation capability is fully supported by Marklin and many of their own older factory designs use this concept.

The problem comes when a Loco crosses from one oval to the other and the pickup slider bridges both circuits.

If the Transformers are in phase, there will be 16VAC on both sides of the transition insulation.

If the Trafo's are out of phase, there will be 36VAC across the transition.

With an Analogue loco, you will get a spark at this point, but with a digital loco running in analogue mode you will risk frying the decoder.

Ok, that's a pain, but not really dangerous.

Now consider this unlikely, but possible scenario.

Little Johnny has been playing with his trains with this exact design.

Mum calls him for dinner, and also calls "Don't forget to unplug the train set". Johnny is a bit eager for dinner, so he does not stop the trains, he simply pulls the first Trafo plug from the wall - at which point the Loco just happens to stop right across the transition - and while the other Trafo still remains connected.

Then he happens to touch the now exposed pins of the wall plug while handling it......

How much voltage do you now think is present on the exposed pins of the removed wall plug (while the other one remains connected) ?

Of course, this is an unlikely, but still possible scenario. But there is nothing wrong "dangerously" or otherwise - the layout complies 100% with Marklin's own track wiring diagrams.

The only thing 'wrong' here is that the Trafos are out of phase (with each other) yet they are still each 100% electrically safe.

Edited by user 11 December 2017 18:05:30(UTC)  | Reason: Typos

Cookee
Wellington
NZ image
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Jay
Offline H0  
#10 Posted : 11 December 2017 08:20:46(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 15,254
Location: DE-NW
Originally Posted by: cookee_nz Go to Quoted Post
With respect, this is only partly correct.
Yep. You ignore that I wrote "With respect to accessories". Thanks for quoting the full text. The highlighted sentence must be seen in the context of the quoted text.
Polarity matters when driving trains. And if polarity matters for driving trains then it is potentially dangerous with older transformers.
Polarity should never matter when feeding accessories.
Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
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Offline cookee_nz  
#11 Posted : 11 December 2017 09:00:23(UTC)
cookee_nz

New Zealand   
Joined: 31/12/2010(UTC)
Posts: 3,948
Location: Paremata, Wellington
Originally Posted by: H0 Go to Quoted Post
Originally Posted by: cookee_nz Go to Quoted Post
With respect, this is only partly correct.
Yep. You ignore that I wrote "With respect to accessories". Thanks for quoting the full text. The highlighted sentence must be seen in the context of the quoted text.
Polarity matters when driving trains. And if polarity matters for driving trains then it is potentially dangerous with older transformers.
Polarity should never matter when feeding accessories.


Hi Tom, my concern was that the distinction may be lost in the bigger picture, but the caution still applies whether we are talking the Red track feed or the Yellow accessory feed, but my illustration was an easier one to relate to and hopefully to visualise.

Regards
Cookee
Wellington
NZ image
Offline Michael4  
#12 Posted : 11 December 2017 10:51:26(UTC)
Michael4

United Kingdom   
Joined: 02/02/2017(UTC)
Posts: 637
Location: England, South Coast
So...back to the beginning, I need to double check polarity. I have done something wrong somewhere.

In theory, or at least as I understand it, if polarity is correct then there should be no problem in mixing lighting current (yellow) from various transformers between linked accessories. I understand why incorrect polarity would cause a problem.

Or, making sure polarity is correct, one could link the yellow supply from two transformers together without problems... though why one would want to...

Right now, apart from the occasional recalcitrant 5146, everything that I have set up works, I'm sure I'll get to the source of the original problem as I dig further and check polarities as I go.
Offline Markus Schild  
#13 Posted : 11 December 2017 11:30:56(UTC)
Markus Schild

Germany   
Joined: 14/01/2006(UTC)
Posts: 1,802
Location: Wurttemberg
Originally Posted by: Michael4 Go to Quoted Post




Or, making sure polarity is correct, one could link the yellow supply from two transformers together without problems... though why one would want to...



Hi Michael,

Don't even think about that. This must not be done and is dangerous in various ways: First of all the short-circuit switch in the transformers does not work any more.

Regards

Markus
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Offline Michael4  
#14 Posted : 11 December 2017 11:36:54(UTC)
Michael4

United Kingdom   
Joined: 02/02/2017(UTC)
Posts: 637
Location: England, South Coast
Thanks Marcus,

I won't!

Best

Michael
Offline H0  
#15 Posted : 11 December 2017 20:56:55(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 15,254
Location: DE-NW
Originally Posted by: Michael4 Go to Quoted Post
I understand why incorrect polarity would cause a problem.
If polarity matters then you probably have an accidental connection between the yellow wires of two transformers, thus operating them in parallel - a dangerous situation that should be avoided.

Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
UserPostedImage
Offline GaryTrooper  
#16 Posted : 28 January 2018 07:00:27(UTC)
GaryTrooper

United States   
Joined: 26/01/2018(UTC)
Posts: 390
Location: Hailey, Idaho
MarklinWiringBooklet.pdf (170kb) downloaded 105 time(s).

See Section 8 "Multiple Transformers on a Layout" in the attached PDF and Section 8.3 to test for transformer polarity.
G - LGB
O - Lionel and MTH
HO - Marklin
N - Mix of manufacturers mostly Kato
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