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Weird short occurred on DCC layout

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  • Member since
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Weird short occurred on DCC layout
Posted by rrebell on Wednesday, October 28, 2020 7:19 PM

I turned on layout after doing scenery work and got a short. Looked around and had left a caulk gun on layout, no big deal, just remove object and restart, wrong. Looked around for something else, nothing. At first I thought maybe I had damaged my digitrax, but removed wires and it was fine. Then after a lot of continuity testing in the area that the short happened and it is the power routing Shinohara turnout that had shorted. Never had this happen before. Now how to fix without replacing turnout. Can that even be done, luckily it was not on the main.

  • Member since
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  • From: Collinwood, Ohio, USA
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Posted by gmpullman on Wednesday, October 28, 2020 7:24 PM

rrebell
and it is the power routing Shinohara turnout that had shorted.

A track diagram would help here.

Power-routing turnouts have specific rules for wiring. Feeders must be from the point end of the turnout.

Any frog-to-frog rail must be gapped. A stub-end siding wouldn't have to be gapped BUT if you add a feeder wire to any rail of the siding you would have to make a gap between the frog and the point where the feeder wire is.

Scroll down to the middle of the page here and read about power-routing turnouts:

https://dccwiki.com/Turnout

My layout was originally all Walthers/Shinohara power-routing turnouts. It was a learning experience but once I grasped the concept, everything was fine.

Is your short dependant of the position of the point rails? Did you recently add track or feeders to the rails connected to the turnout? Is your turnout on a passing siding or other arrangement where there is another frog-connected turnout to it?

Good Luck, Ed

  • Member since
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  • From: Shenandoah Valley
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Posted by BigDaddy on Wednesday, October 28, 2020 8:06 PM

Is the caulk gun just a red herring?  Years ago I had Shinohara turnouts and Rix Rax machines.  Frogs were powered from the RR and it worked fine in DC

Henry

COB Potomac & Northern

Shenandoah Valley

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Posted by rrebell on Wednesday, October 28, 2020 8:08 PM

Found it! No what happened is the frog shorted though more than one insulated rail joiners and must have been small enough to give intermitant readings. I would do something and it worked for a second, then shorted. Finally I recut every peice of rail that had insulated joiner on it and on the last one the fix stayed, so far, LOL. Hey at least I know how robust the system is.

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Posted by rrebell on Wednesday, October 28, 2020 8:11 PM

BigDaddy

Is the caulk gun just a red herring?  Years ago I had Shinohara turnouts and Rix Rax machines.  Frogs were powered from the RR and it worked fine in DC

 

No, it was what caused the other problems as layout has had no problems for months, no wiring has been done since then either, all work of that type has been on a yard that is not even conected yet to the main and the yard is DC till I get it perfect, most is done but have a few spots around the turntable to address.

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  • From: west coast
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Posted by rrebell on Wednesday, October 28, 2020 8:20 PM

So I blew it blaming it on the turnout, who would fiquere more that one short appearing where everything was fine the day before (thought it might be the turnout as the earlier version of them had little copper pads on the point that I had one flatten and connect once.

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Posted by rrebell on Thursday, October 29, 2020 10:08 AM

Now the question is how much power goes through when a short happens, found another insulated joiner that was now lower on one side, no short but in same area.

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Posted by Overmod on Thursday, October 29, 2020 11:17 AM

Potential (no pun intended!) concerns from massive shorting across DCC:

Very large possible current, even in the short period between 'activation' and automatic cutoff.  This might have resulted in arcing at areas of relatively low conductance, and particularly across thin 'insulated' gaps.  Arc plasma at elevated temperature might easily soften or char insulated joiners or other material.

While I think it less likely, some ohmic heating of the rails might have occurred, with the resulting expansion pushing on and perhaps damaging joiners.

I'd expect that 'charred' insulating joiner material (e.g. if fiber) to be more conductive, possibly 'enough' to cause continued conduction across gaps (resulting in what are likely different shorts).  Cumulative damage might be occurring at such points.

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  • From: west coast
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Posted by rrebell on Thursday, October 29, 2020 4:12 PM

Than you. Never had this problem with DC and am ussually very carefull but caulk gun was on other side of hill, never saw it till the short.

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