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Troubleshooting a reverse-loop/short problem?

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  • Member since
    February 2009
  • From: Warren, MI
  • 55 posts
Troubleshooting a reverse-loop/short problem?
Posted by gtw1969 on Wednesday, December 23, 2009 9:06 AM

Hello all,
I'm having a problem all of a sudden with my reverse loop wiring. When I go to throw my reverse loop switch, I recieve a short through my DCC controller. This is very strange, as it was working fine before and all of a sudden doesn't work. However without activating the reverse loop/polarity switch, trains run fine on my layout.

Let me tell you more about my situation. I wired a manual reverse loop using a DPDT and two lamp (LED) indicators, using blocks to cut-off the reverse loop from the rest of the track plan. I did this after unsuccessfully installing an auto-reverse module, which didn't work well with my Bachmann Dynamis DCC controller. After installing the reverse loop DPDT, including tortoise motors for the turnouts, and a complete control panel for that area of the layout. Everything worked well....for more than a month or two. Now all of a sudden it doesn't work when I try to switch the polarity while my train is within the loop. In my efforts to troubleshoot it, I removed the control panel to observe if there was any loose connections. Doesn't appear to be any. Also checked the wire routing....again, doesn't appear to be an issue either.

Since working on the DPDT installation, the only other things I did to the track/layout was add additional yard "stubs" to my yard. I did this without using rail joiners. I can't see how this would be a problem though, as I'm still able to run trains without any shorts happening? I also added feeders to a few added tracks on my turntable. Again, trains run fine after doing this.

Could the DPDT have gone bad for some reason? I'm by no means an electronics expert, so any help would be much appreciated. Please reply with any help or questions regarding my situation...I can add additional information or pictures if needed. Thanks!

Steve Rigelhof http://sr-graphics.net
  • Member since
    July 2006
  • From: Vail, AZ
  • 1,943 posts
Posted by Vail and Southwestern RR on Wednesday, December 23, 2009 12:29 PM

My first guess would be that one of the gaps isolating the loop has closed up, so I would check that.

Then I would take power off the layout, get out the trusty ohm meter, and see what is hooked to what in both switch positions.  The chances that the switch failed are tiny, really tiny.

I would also think carefully about the last thing you did before it stopped working.  The problem is very often where the hands were last.

Jeff But it's a dry heat!

  • Member since
    February 2001
  • From: Poconos, PA
  • 3,948 posts
Posted by TomDiehl on Wednesday, December 23, 2009 2:51 PM

There's also the possibility you're using the reversing switch backwards. Are you going into the reverse loop in the same direction? Is the switch set to the same position as it was in the past?

Don't be insulted, the first rule of troubleshooting is to look for the obvious first.

Smile, it makes people wonder what you're up to. Chief of Sanitation; Clowntown
  • Member since
    December 2009
  • 146 posts
Posted by Owendubya on Friday, December 25, 2009 4:35 PM

a couple of things come to mind. first are you using the plastic rail joiners to isolate BOTH sides of the loop? also check the soldering on the DPDT switch, if it isn't shiny but a dull grayish color then you have a cold solder which could be the problem, also check the soldered connectors for the power within the loop

  • Member since
    February 2009
  • From: Warren, MI
  • 55 posts
Posted by gtw1969 on Sunday, December 27, 2009 9:07 AM

Thanks for all the advice guys!

I've been working on scenery on another part of the layout as I've been recieving posts to this thread. I guess you could say it allows me to ease away from the electrical problem, as I seem to have such a difficult time with it. In any event, I will try the ideas you have suggested. So far I tried to trace back to what might have caused the problem in the first place....things I did after I had the loop working initially. So far I can't seem to track it down...I've even cut a few of the track feeders and cut power to the other half of the layout (things I did after getting the loop to work). Still nothing. As far as the soldered connections are, they seem to be ok....not the grayish color mentioned. My next step is to break out the meter and see if I can track it down that way. It just seems it has to be something stupid....something I've overlooked. I'll report back if I find anything. Till then, thanks for the help, and any other help you may be able to provide!!!

Steve Rigelhof http://sr-graphics.net

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