Reversing Loop Angst! - PSX-AR & Kato Double Crossover (N Guage)

PapaG May 21, 2020

  1. PapaG

    PapaG TrainBoard Member

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    Oh yeah!! I can see that now! Once I get my PSX1 issue taken care of, and confirm my insulated rail joiners are doing what they’re supposed to, I’m rewiring that crossover!

    I never would have even considered that on my own! Good catch!
     
  2. RBrodzinsky

    RBrodzinsky November 18, 2022 Staff Member TrainBoard Supporter In Memoriam

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    You really don't need a PSX1 for those five pieces of track, unless you eventually plan to enlarge everything
     
  3. PapaG

    PapaG TrainBoard Member

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    Rick,
    No, no... this little figure-8 is just a means to an end. With this layout I can turn my door upside-down to access my circuitboards and buss-lines as I’m trouble shooting.

    The layout this testing and troubleshooting is all in support of is much larger (see pics), though still relatively small. The layout is a folded dogbone on a 32”X80” hollow-core door. The piece of missing track in those pics is the crossover I’m trying to incorporate through the exercise with the figure-8.

    I’m sure that I’m doing some things that aren’t absolutely necessary given the relative simplicity of my layout, but the ambition is to develop certain skills and gain experiences as I build this. So, I’m embracing that to advance my skills.
     

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  4. nscalestation

    nscalestation TrainBoard Supporter

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    I was using the Kato insulated joiners, it's just that I had one time where the rail had slipped on a track section and put enough pressure on the insulating part of the joiner that it contacted the rail on the other side. So I am just saying don't take it for granted that those things provide a sure gap and check with an ohm meter, etc.
     
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  5. PapaG

    PapaG TrainBoard Member

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    Jake,
    Here’s where we are...

    I installed the jumper on the PSX1 to set the trip level, and as soon as I powered the layout up it detected the short at the crossover set to cross. After wiring it as you suggested that short was relieved.

    I also verified that the insulated rail joiners are doing their jobs.

    But now I have some new issues, and it could get a little confusing trying to describe it. But, here goes...

    Imagine the dogbone - reversing loop on the left = AR Zone 1; reversing loop on the right = AR Zone 2; crossover and 1 piece of track connected to all four points comprising the shank = PSX1 Zone.

    1) With the crossover set to pass and traveling clockwise (cw), PSX1 detects a short as the loco exits AR Zone 2.

    In this configuration and this direction of travel, this single fault is detected.

    2) With the crossover set to pass and traveling counter-clockwise (ccw), PSX1 detects a short as the loco exits AR Zone 2.

    In this configuration and this direction of travel, this single fault is detected.

    3) With the crossover set to cross and traveling cw through AR Zone 1 & ccw through AR Zone 2, PSX-AR #2 detects a short as the loco exits AR Zone 2.

    In this configuration and in this direction of travel, this single fault is detected, and it’s the only fault detected by one of the AR’s.

    4) With the crossover set to cross and traveling ccw through AR Zone 1 & cw through AR Zone 2, PSX1 detects a short as the loco exits AR Zone 1 AND as it exits AR Zone 2.

    This is the only configuration and direction of travel in which more than one fault is detected.

    I disconnected the reversers and reconnected them to the opposite reversing loops. The fault associated with AR Zone 2 that the AR detected (example #3) is inherent to the loop itself. Both AR’s detect the same fault in the same location given the same criteria of crossover configuration and direction of travel.

    I reversed the polarity of the feeders providing power to the reversing loops and the crossover in an attempt to relieve the faults, but no variations or configurations in polarity for these feeders resolved the faults.

    I also removed the pieces of track on which the loco was shorting and replaced them with other pieces. This also had no affect.

    Any ideas?
     
  6. RBrodzinsky

    RBrodzinsky November 18, 2022 Staff Member TrainBoard Supporter In Memoriam

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    Just for kicks, try bypassing the PSX. When I was building the JACALAR and still using a Zephyr, I had a spot, where the track transitioned between a PSX and a PSX-AR and the PSX raised a short on every transition. After many discussions with the DCC Specialties folks, they asked if I could isolate one piece of track between them and not have it protected. From then on, every thing worked fine. Later, when I put a DCS-100 on the layout, and increased the trip points, I was able to move that piece of track back to the PSX.

    Basically, the units get very finicky at their lowest trip points.
     
  7. PapaG

    PapaG TrainBoard Member

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    Rick,
    That was going to be my next test, but it was getting late last night and, quite frankly, I’d simply had enough of model railroading for one day, lol.

    Removing the PSX1 from the scheme is on the agenda for this evening... I’ll let you know what happens!
     
  8. PapaG

    PapaG TrainBoard Member

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    Rick, Sumner, Jake, Brad,
    I just wanted to update all of you...

    We have operational reversing loops with the double crossover!!

    Each of you contributed information and advice that has resulted in a better running layout for my grandson and I.

    Jake, it started with you recognizing the deficiency in my original wiring scheme and, Rick, it ended with your support throughout and the information re: the PSX1’s finicky operation at the lower trip settings, with Sumner and Brad providing great information and things to consider and verify along the way.

    This has been a source of frustration for months, and a roadblock to our being able to commit to a layout and beginning to secure track, and to moving forward with our scenery and town/industry ideas.

    Your help has been the key to unlocking the rest of all we hope to do and learn. I can’t thank you guys enough.

    What a Team!!
     
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  9. BigJake

    BigJake TrainBoard Member

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    Whew, glad you got it working!
     
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  10. PapaG

    PapaG TrainBoard Member

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    Rick,
    Just to follow up on the suggestion you shared regarding wiring a length of track between the PSX-AR and PSX1 that is not protected by the PSX1. I've been reading the PSX1 Manual over and over... and then it dawned on me that I had read the solution several times and didn't realize it.

    The manual says...

    CV55=1
    CV55 sets the duration between a fault being detected and when power is shut off to the output of the PSX. If CV55=0 the power will turn off in less than 1ms, like a fast-blow fuse. If CV55=1 the PSX creates a delay between those two events, like a slow-blow fuse. The duration of this delay is set by CV65

    CV65=XXX
    The value of CV65 / 8 = duration of the delay in milliseconds (CV65 set at 80 = 10ms delay). Increasing the CV65 value from the default (which is 24, or 3ms) in increments of 8 (1ms / increment) until nuisance trips no longer occur. This will set the delay to the shortest time necessary to address the nuisance trip while still providing the best and fastest response to a legitimate over current condition.

    So, what I did is set CV55=1 and then CV65=128 (which is half of it's limits) and then started reducing the CV65 value until I started getting the nuisance trip again, then increased the value until it stopped. Now my layout works perfectly without the additional powered sections of track between the two devices. Just thought I would share in case you or others were interested in a more systemic approach to addressing this problem.

    Peace!
    G.
     
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