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DCCtechnical question

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  • Member since
    January 2005
  • From: Winnipeg Canada
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DCCtechnical question
Posted by Blind Bruce on Tuesday, September 11, 2007 12:12 PM
I have a DCC loco that will operate normally when going clockwise around my HO oval but shorts out the Zephyr when going the opposite direction. The oval is not a consistant radius but is minimum 20" and has curved turnouts where the shorts show up. (Shinohara code 83 #6.5) I could troubleshoot a DC loco for shorts but I have no idea where to begin with DCC since it is basically AC. Would a shorted tire to wheel do this?

73

Bruce in the Peg

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Posted by ndbprr on Tuesday, September 11, 2007 12:45 PM
Obviously something is shorting out running in one direction.  You don't say what kind of engine or if it is always in the same location.  if it is always in the same location kill the power when it stops and look over any points on the engine that may be touching.  It could also be something internal in the wiring that is causing it.  Intermitent problems are a bear to find and fix.  It is going to take patience and resolve.  Also try turning the engine end for end and see if it stalls in the same point in the other direction.  Your two choices are either in or on the engine and shorting two rails in the turnout in my opinion. 
  • Member since
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  • From: Bettendorf Iowa
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Posted by Driline on Tuesday, September 11, 2007 12:58 PM

I've had the same thing happen with my shinohara turnouts. Its not your engine. If the turnout is thrown and you're going towards the direction of the frog, check to make sure that your wheels are not contacting both the frog and the oustide rail. This is true of the "Power routing " turnouts, not the DCC friendly turnouts. I'm not sure which you have. Anyway my solution was to "bend" the frog rail slightly inward so that the wheels don't both touch the frog and the outside rail.

I've had more problems with my curved turnouts doing this than anything else.

"edit" I see you have curved turnouts. Well thats your'e problem. Just bend the frog slightly inward so that the wheels DON'T touch both the frog and outside rail. Problem solved.

Modeling the Davenport Rock Island & Northwestern 1995 in HO
  • Member since
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  • From: Vail, AZ
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Posted by Vail and Southwestern RR on Tuesday, September 11, 2007 1:04 PM

On a more general note, a short is a short, whether it is a DC system or a DCC system.  The difference being that in most DC systems a short (duration) short (I crack myself up, sometimes Clown [:o)] ) doesn't trip the power supply, you coast through it, and keep going.  DCC systems trip sooner (there are reasons this is generally a good thing), and so a short that did not hurt in DC is a pain in DCC.  That said, based on the info given the problem is most likely near the frog of a turnout.

 

Jeff But it's a dry heat!

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  • From: Bedford, MA, USA
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Posted by MisterBeasley on Tuesday, September 11, 2007 2:14 PM

I'm not sure about the Shinohara's, but on some Peco turnouts the frog has a thin black plastic insulator down the center, with metal on the sides.  If the wheels are wide enough (and this could refer to any metal wheels) and they line up going down the frog such that they cross the insulator and end up touching both sides of the frog, you'll get a short.  The solution is typically to apply a bit of clear nail polish to the frog to coat one of the frog rails and prevent the contact.  As long as the other wheels are making good contact at that time, there should be no loss of power to the engine.

This can be a directional thing, because the engine will take a slightly different path across the frog depending on which way it's going.

It takes an iron man to play with a toy iron horse. 

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  • From: Vancouver Island, BC
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Posted by selector on Tuesday, September 11, 2007 3:31 PM

Bruce, I am 100% certain that you have a short at the tires of one of the axles as it enters the frog.  It probably takes place at the end of the frog away from the points, but not necessarily...it may be at both ends.

I use a cut-off disk, a thin one, using a Dremel-like instrument, and cut gaps on the inside frog rail, that is, the frog rail on the diverging, or inner, route. For a curved turnout, you only need to gap this one rail to keep your offending tire from making contact with two rails at the same time just beyond the black plastic spacer.

In case I am confusing you, trace the closure rails to the frog.  Just as they are about to meet, there are two plastic spacers matching the two on the other side of the frog...where the frog rails begin to diverge away from each other.  In my experience, it always seems to be on the far side that things go wrong, so that is why I suggest cutting a gap in the inner frog rail.  The gap should be the better part of a full half-inch outward from the plastic spacer on that rail.  That cut allows the rail to separate from its neighbour on the through route just a bit more, and it also cuts power to it.  So, your offending axles(s) will still let the tire bridge the two rails, but now that this tiny piece is dead, you won't get the short there.

Been there, done that.  I also tried using clear nail varnish to paint over that same bit of rail as some guys do, but it turns it black and it wears off.  Cutting another gap is permanent, and works!  If this might present a challenge to you, you know where to get help nearby.

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