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  • An interesting problem

    Hi Guys,

    There is a wye on my layout, and I've had the pleasure of using it with an MRC AD520 auto-reverse module for the last ten years. My small (about 4x12') HO switching layout is run with a NCE PowerCab and I always have 4 locos on the track.

    Just lately, while running over one leg of the wye (it's always the same section) I short out. I have to push the loco by hand past the wye insulators, and everything works fine again. It is a very intermittent problem. Maybe it short circuits once every dozen or so passes. And it seems more much more reliable when the other locos are still, and all the sound and lights are off.

    Though inexpensive, replacing the module would be a pain, as it difficult to access.

    The track and wheels are clean and treated with CRC 2-26. Everything runs like a dream except for this new bug. The direction of the loco matters not. I suppose the module isn't switching the polarity when it senses a short, but it only every happens on the one leg.

    Boy, I wish there was a better explanation/quick fix.

    ek :erm:

  • #2
    One more fact...

    It doesn't seem to matter if the polarity even needs reversing! I JUST ran a train forward through the wye to the west. No problem. I then ran the same loco across the same track in reverse, back to the east, and shorted out when I hit the wye. Hmmmm?

    Maybe this has nothing to do with the module, and I have a loose rail joiner or something?

    Must remember the loco isn't stalling. It's shorting out the whole layout. double hmmmm?

    Comment


    • #3
      Kyle, a couple of things to check. First, make sure that none of the gaps for that section of track have closed up. From what you are describing, it sounds like the reverser is not reversing! Closed up gaps, or the reverser went bad are the only two things I can think of.
      Mark

      Comment


      • #4
        I think Mark has hit it on the head. Kill the power and take out your ohmmeter and look for the shorted gap. If the gap is too tight, the wheels may just be 'bridging' the gap enough to cause the short. Try a different engine on that section, and see if the failure happens exactly the same. Your second post contradicts your first post with the loco direction not mattering, then mattering. Let us know what you find.

        Jim
        Take the red pill

        Comment


        • #5
          Hi Guys,

          Jim, my second post is an attempt to explain that the track polarity hadn't changed so the significance of the auto-reverse module is in question. A loco passing over this section can short out the layout going either way.

          I did look at the insulated gaps, and one seemed VERY close to touching. I spread the gap apart a bit with a knife blade. We'll see if that helps.

          Because I don't have this problem when the other locos are idle and their sounds are off, I'm wondering if this issue is exacerbated when there is more of a electrical load put on the system? Wouldn't all those noisy, running locos draw more current away from the wye? (Sorry about the terminology, I'm no electrician)

          ek

          Comment


          • #6
            Kyle,

            Where are the gaps? Are they near a turnout and is it possible that the problem is actually that the locomotive is shorting out on a non-DCC-friendly turnout?

            Mike
            _________________________________________________

            Not everything that is faced can be changed, but nothing can be changed until it is faced. James Baldwin

            Comment


            • #7
              Hi Mike,

              Nope, all my turnouts are very amicable with DCC.

              Kyle

              Comment


              • #8
                Ok. I thought that was probably the case.

                Intriguing . . .

                Mike
                _________________________________________________

                Not everything that is faced can be changed, but nothing can be changed until it is faced. James Baldwin

                Comment


                • #9
                  I love Tortoises and believe them to be the best, but even Tortoises can cause problems as they age. I am going to assume you are using the contacts to direct power to the frog, and if so, you may wish to change out the Tortoise or check it out regarding the contacts thoroughly. I also just recently (today) had a similar situation that was alleviated by correcting the contacts that controlled the frog.

                  Good luck and regards, Vic B.

                  Comment


                  • #10
                    quote:


                    Originally posted by engineerkyle


                    Hi Guys,

                    Jim, my second post is an attempt to explain that the track polarity hadn't changed so the significance of the auto-reverse module is in question. A loco passing over this section can short out the layout going either way.

                    I did look at the insulated gaps, and one seemed VERY close to touching. I spread the gap apart a bit with a knife blade. We'll see if that helps.

                    Because I don't have this problem when the other locos are idle and their sounds are off, I'm wondering if this issue is exacerbated when there is more of a electrical load put on the system? Wouldn't all those noisy, running locos draw more current away from the wye? (Sorry about the terminology, I'm no electrician)

                    ek


                    Ahh! Are you feeding the reverser with track power? You may be dropping the available power to it (switching capability) with a heavy load (multiple engines, sound, other gizmos, hanging off a single supply. Figure 1 - 1.5 amps per sound equipped loco. Total the number, and look at your power source, booster, whatever you are using for power to the track and see if you are at or exceeding the recommended load. A 5 amp command station really like about a 3-3.5 amp load. Ny the time those electrons get to the farpoint from the main feed, it can be even less. those sound equipped locos are drawing a lot of power, even just sitting idle.

                    Jim
                    Take the red pill

                    Comment


                    • #11
                      quote:


                      Originally posted by BurleyJim



                      Ahh! Are you feeding the reverser with track power? You may be dropping the available power to it (switching capability) with a heavy load (multiple engines, sound, other gizmos, hanging off a single supply.

                      Jim


                      That sounds like it. But let me run with that wider gap and see what that does.

                      EK

                      PS I wish guys would read the thread before plugging torts... this has nothing to do with them.

                      Comment


                      • #12
                        Burley Jim makes a good point.

                        I have broken up my layout into 6 blocks and am using 1156 tail light bulbs for short control.https://www.nmra.org/sites/default/f...1502Shorts.pdf

                        Anyway, I had a reverse loop that I connected to the DCC bus wires in the block and the auto-reverser did not do the job. The 1156 bulb lit up first. I then realized I had to wire the auto-reverser to the bus OUTSIDE of any block, that is directly to the DCC system before the bus went to the blocks and that took care of that issue.

                        So if you have added any short control circuits or added locos that pull some heavy duty current, this could cause the problem. If nothing has changed in the years you have been using it and this problem just cropped up all of a sudden, then back to the turnout or Tortoise.

                        Good luck and regards, Vic B.

                        Comment


                        • #13
                          Well, It's not the gap.

                          I did replace an Athearn Geep for a BLI Switcher, and that's when the problem started, if I recall correctly. Could be the BLI draws more current than the Athearn, just enough to put me over the threshold.

                          Anyways, before I use that leg of the wye, I shut off the sound on all locos and crawl through it, which has been rectifying the problem. This beats digging under the layout and replacing the reversing module, at least for now...

                          Thanks for all the suggestions,

                          ek

                          Comment


                          • #14
                            That's wye beyond me. Sorry.

                            ed

                            Comment


                            • #15
                              quote:


                              Originally posted by engineerkyle


                              Well, It's not the gap.

                              I did replace an Athearn Geep for a BLI Switcher, and that's when the problem started, if I recall correctly. Could be the BLI draws more current than the Athearn, just enough to put me over the threshold.

                              Anyways, before I use that leg of the wye, I shut off the sound on all locos and crawl through it, which has been rectifying the problem. This beats digging under the layout and replacing the reversing module, at least for now...

                              Thanks for all the suggestions,

                              ek


                              Replacing that reversing module probably 'ain't gonna fix the problem'. You need a more power, or lower expectations.
                              Take the red pill

                              Comment

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