Short circuit when driving over points

[JeffPreston]

Hi All!

Has anyone else experienced this?

Brand new Farish WD Austerity - lovely loco and recommended by many - but... causes a short circuit when crossing over brand new Peco Streamline code 80 large radius points ('insulfrog') at the slowest speed on my DCC layout (presently in its early days of construction).

Running fine for days until I started to apply power to the other parts of the layout. It can run all over the layout, pulling coaches, approaching points from any direction and also driving forward or backwards and no problems at all.

Then I finally applied the magic recipe of all tracks powered and driving at a speed of "1" on the DCC controller and that was it. Short circuit. All stop.

I've found discussion of this on the web and an excellent resource and solution here...

http://www.brian-lambert.co.uk/DCC.html#A

Problem would seem to be...

1 - Wheels too wide
2 - Driving very slowly
3 - DCC deliberately and wisely shuts off at the briefest short

Solution is a couple of extra, short feeder wires and a couple of insulated rail joiners.

Not a lot, but what a shame as I have the tracked fixed down and working beautifully.   

Still - better than finding this out after ballasting! 

Any stories? Thoughts? Rants? "Get over it Jeff"?   

[Malc]

It is easy to be wise after the event, but it is worth putting IRJs on the V of all points, just in case

[JeffPreston]

Hi Malc!

Absolutely - I'm doing just that. 

So far so good - the solution works very well.

Part of me is disappointed that this phenomenon could have been made more clear somehow...

Novices like me will imagine that - well - the stuff just works! Part of me wants to ask that a label be affixed to the box of the loco in question which reads:
"Warning - likely to cause short circuits when driven at slow speeds over Peco insulfrog points on a DCC layout! Insulating rail joiners advised!" 

[bluedepot]

normally it is wheel back to backs that are out in my experience


tim

[JeffPreston]

Wire the frogs through the seep aux points to sort that out...

As a novice I don't know what you are describing. 

Can you explain in more detail or direct me to a source that can? Only if you have time, as I've already pressed ahead and am solving the problem - although it is taking extra time...

[Bealman]

I am assuming Only Me is referring to seep point motors?

[JeffPreston]

Thanks for the detailed information - right now I am using the method I described earlier in the post as I am going to be fitting motors a little later and so have no motors or electrical switches, but I would rather like to see the brand new loco complete a run around of all parts of the brand new track without a short circuit!

[Bealman]

Yeah, I can see what you are getting at and it is certainly valid. My personal opinion is that it's all tied up with the lack of mass of things in N but also the long history of Peco insulfrog points.

In this game there can be a lot of cussin' & swearing and false starts! 

George

[Newportnobby]

ok I'll try.

on any set of points, where the two tracks part you will see a "V" section of track which joins at the end of the "V" to the two opposing lines and thus the two opposing sides of the DCC bus...(using electrofrog it's metal) on insulfrog its a V piece of plastic.

Now each section takes power from the next piece of track (unless you have insulated it with Insulated Rail Joiners (IRJS)) so picture your loco passing over ever so slowly and the wheel flange touching both parts at once of the "V" at once, this is enough to cause a short to the DCC BUS as the wheel shorts both sides of the bus out...

this picture shows what I mean,



So you would insulate the ends of the "V" with IRJ's and power the inside of the V with an external switched source so that it changed depending on which way the points are set.... On a Seep motor you have extra solder tabs to wire onto and an AUX output wire which can be wired to the "V" or you could just rely on using the rail connections when the points are thrown..

like this ...

[smg id=12192 type=preview align=center caption="irjs"]

Having asked about this in another thread about Seeps and electrofrogs, thanks to your post I'm starting to get there, but still need to see a pic of how the wiring is made underneath the point - pretty please (sorry to hijack this thread)

[Newportnobby]

Thanks very much - PM sent

[EtchedPixels]

causes a short circuit when crossing over brand new Peco Streamline code 80 large radius points ('insulfrog') at the slowest speed on my DCC layout (presently in its early days of construction).

Either

1. The gauging is out on the wheels (the wheels are too far apart). Not that common with modern Farish but happens.

2. The point itself is bowed/twisted

In both of those cases the locomotive wheel can touch both of the diverging rails from the frog. Normally it doesn't matter even then but if you are feeding power to both ends of the point on both tracks you can then see a short.

The fix is to check the point is flat and level, and to test with other locomotives carefully.

If you get the problem with other locomotives you've got a twisted or maybe just misassembled point (almost always in my experience however its one that is twisted usually by over zealous use of trackpins)

If only that loco trips it then the loco is probably out of gauge. In that case I happily adjust the gauge of the wheels on most of my locos (some Dapol it's a very bad idea and should be returned if out of gauge)

If you want to fudge around it then fitting an insulated joiner here and there will cover up the sins but an out of gauge locomotive is likely to derail on some other track formations so hiding it is not IMHO the best approach.

The diagrams being posted apply to Electrofrog points so have *nothing* to do with this situation at all !

Alan