Reversing Loop - Need Help

Discussion in 'FAQs' started by Mannix, Mar 24, 2007.

  1. Mannix

    Mannix Member

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    I installed a reversing loop on my layout, but I get a short as soon as I plug in my Prodigy Express DCC. I am attaching a crude drawing of the part of the layout where I have the reversing loop. I have installed insulated connectors at numbers 1, 2, 3, & 4. I wired in the MRC Auto Reverse Module on both sides where I have the #1 insulated connectors. The red wires are on the right side and the yellow wires are on the left side. I hope my drawing gets attached to this post.

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  2. steamhead

    steamhead Active Member

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    Mannix,

    You need to isolate the section of track that goes from 2 to 3. That is the section that causes the short circuit. The reverse module shoud be wired to this section and the main line.
  3. cidchase

    cidchase Active Member

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    Mannix, I'm not so sure that there is anything wrong with the way you show it.
    I would disconnect the rev module and and test that no short exists across any rail
    gap.

    If all OK, apply DCC power. If it shows no short, then I would jumper(alligator clip)
    each rail across the gaps at 1. If it still shows no short, I would switch sides with one
    end of those jumpers (cross over the polarity to the reverse section).

    This would duplicate the power function of the reverse module. If the module won't
    work after all the tests prove out, I think I would suspect the module.

    Maybe I'm wrong, but I really don't see a short circuit there.
  4. cidchase

    cidchase Active Member

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    I'll qualify that. What about those crossovers on the section going off to the right? Does that "main line" loop there off the page?? If so, no bueno. Did this run before you added the 1 to 4 connection?
  5. steamhead

    steamhead Active Member

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    Cid, if you follow the outside rail starting at point 1 and go around the loop and down the section towards #2, you will see that it turns out to be the inside rail once you go over that turnout. That's why you need to insulate that 'REVERSING' section. It is causing the short.
  6. steamhead

    steamhead Active Member

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    What may or may not happen off-stage does not change the fact that that section is causing a short. There may be other convolutions we don't know about, but the one we do know about has to be fixed first.
  7. cidchase

    cidchase Active Member

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    The whole section fron 1 to 4 to 3 to 2 is completely isolated (according to the sketch)
    from the main line, is it not? I just don't see a short there. If there is one, across which gap (1,2,3,4) would it exist? I'm following that rail around and I don't see the inside become the outside except at 1
  8. cidchase

    cidchase Active Member

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    If the 2 to 3 section were removed, there is still a reverse loop, I think.
  9. steamhead

    steamhead Active Member

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    Cid, I believe you're right...It's just that the reversing section would normally be the section going from the turnout at #3 going to #2. But here that's been "pushed back" to #1. So, like you say, the question is...did it work before you wired in the module? If the module is a new addition, how did you reverse the polarity before the module was put in? Maybe the module was connected wrong...
  10. Mannix

    Mannix Member

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    Reversing Loop

    Yesterday I built the reversing loop from 2 to 3. Prior to that installation I did not have a reversing loop and everything worked fine. I did not try anything prior to installing the reverse module and that was the last thing I did after putting in the roadbed and tracks so at this point I don't know if that is the problem or not. I will try the suggestions that you guys posted and see what happens. I definitely want a reversing loop as it will add a lot to my layout. Thanks to all of you for your help.
  11. steamhead

    steamhead Active Member

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    Ok...Did you put in the turnouts at 2 & 3 as well?? When you say you put in isolated connectors..Did you put them in BOTH rails at each point that you note on your diagram..??
  12. Mannix

    Mannix Member

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    I put in the turnouts at 2 and 3 yesterday, and I insulated both rails at points 1, 2, 3, & 4. Steamhead,
    this afternoon I disconnected the yellow wires of the reverse module and when they were disconnected I did not have any short in the layout. I then connected the yellow wires to the left of 2 so they are in the reversing loop and the red wires are connected to the main line and once again I had a short. According to the directions that came with the reverse module, the red wires are to be soldered to the main line and the yellow wires to the reversing loop. That is what I did. Any suggestions? I am at a loss!!
  13. steamhead

    steamhead Active Member

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    Hmmm...Seems like you've done everything right...When you say you did not have a short after removing the module, does that mean you were able to run trains without any problems..?? You don't say, but do you have a separate power feed into the reversing section..?? If you do disconnect it.
  14. Mannix

    Mannix Member

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    Yes, after removing the module I was able to run the trains. I do not have a separate power feed into the reversing section. Tonight I insulated the reversing section at 5. Once again I did not have a short on the layout, but I did not have any power in a short section prior to the reversing section where I marked in the attached new diagram. When I tried to run a locomotive into the reversing section at 5, I got a short. Also, there is no power in the reversing section. One small change can really mess things up.:oops:

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  15. steamhead

    steamhead Active Member

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    Ok...Just one more question...Where in your layout is the power feed to the track..??
  16. steamhead

    steamhead Active Member

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    Oh...'nother one...Do you have a voltmeter..??
  17. Mannix

    Mannix Member

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    I just removed the insulated connector at 1, and now I have power where I indicated on my last diagram that I had lost power. Also, I can now come into the reversing section at 2, but when I come out at 5 I get a short. So now everything is working fine, except when my locomotive comes out of the reversing section at 5. When I was building the layout, I installed many feeder wires from the track bus throughout the layout so all sections would be equally powered.
  18. steamhead

    steamhead Active Member

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    Well...I presume the reversing module is still not installed..?? It is normal for the train to be able to go into one end of the reversing section and short at the other end. Do you have feeders into the half loop section between 1 and 3..?? How 'bout at the section between 2 & 3..(the now reversing section) ??
  19. Mannix

    Mannix Member

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    I had another idea so I removed the insulated connectors at 4 to see if that would make a difference; however, that didn't solve the problem, but I left them out as apparently I don't need them. I also removed them at 3, but that didn't make any difference as I still get a short when my lcomotive comes out at 5.
  20. steamhead

    steamhead Active Member

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    I meant between 2 & 5...(in the new diagram...)