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  • SCX Digital Power Jumper Track Mod

    This is a post I created on SCX Worldwide that I thought I'd share here since more questions have come up regarding how a jumper can be made for the SCX Digital System.

    __________________________________________________ _________________________________


    Disclaimer: What you are about to read is not meant as a "how-to" post and thus I do not recommend anyone to perform this mod unless you feel absolutely comfortable w/ the concept of how it works. Any mistake made in how the wiring is applied will cause damage to the Control Unit / Pit Box which will in turn not be covered under the SCX two year warranty.

    Hey everyone,

    I thought I'd share some pics of my latest mod for my SCX Digital track. This is a power jumper wiring harness I've created to help transfer power to the furthest point of a layout to compensate for any power lags. I will be implementing this on my next layout which is going to about about 111 linear feet in length (so it will be mounted about 55 ft from the main terminal to hit the midpoint).

    I have created two tracks (one for transferring the power and the other to receive). Let's check out the pics.

    The Power Transfer Track (to be located near the terminal track)



    The different colored wires you see soldered onto the connection points of the track represent the following:

    Red = Track Rail (+)
    Black = Track Rail (-)
    Yellow = Powerline

    If you notice, I'm also using what are called molex plugs as an interface for the actual wire jumper that would go between the tracks. I did this for the convenience of being able to unplug the jumper whenever I did not need it or to provide the flexibility of make varying length wire jumpers dependent on my track size.

    Now here are some close up pics of my soldering job to the different jump points.







    The Power Receiver Track (to be located @ the remote point)

    This track is really no different than the first. However, what I did differently was to add two sets of molex plugs for the purpose of allowing the jumper wire to come out of either side of the track depending on what direction the track was facing. (Note that on both tracks I have a piece of yellow tape w/ an arrow. It is crucial that the tracks be facing the proper direction of travel when setting up any jumper assembly. By not doing so, it will damage the Pit Box or Control Unit.)



    In addition, another benefit of the two sets of plugs would be to provide a "daisy chain" option one day if I wanted to route another jumper to a 2nd boost point. I doubt I would ever have the need to do so but it's prepped just in case.

    Now here is a view of the Receiver Track from the side showing the "exposed" Powerline. (Note that this is an "older version" of an SCX Digital track section that was designed to have the Powerline run under the slot. The "newer version" now runs the Powerline "under" the outer power rail in the form of a shielded copper wire.)



    And thus, if you notice closely in the pic above, the Powerline on the left has been insulated with what is called "liquid electrical tape". I perform this procedure on all my older SCX Digital track w/ the exposed Powerline as a safeguard against possible shorting. And of course, I had the right side insulated shortly after this pic was taken.

    Now here is my final pic showing how the jumper wire looks like and connected between the two tracks.



    The jumper utilizes an 18 gauge wire which I feel is adequate for this job (any thicker and I would not be able to crimp them to molex pins). I should note that the wires soldered under the track is a 'fairly thick" single stranded copper wire. I'm uncertain of the exact gauge but it is normally used as phone wire.

    So that's really it. I have done some tests to see if it works properly and it certainly does deliver. The ultimate test, however, is when my next layout is built and then we'll see for sure how the system responds (I am expecting improved response and more even power).

    If anyone has questions about it (because I never meant this as a "how to" post), feel free to reply and I'll do my best to fill in any information I left out.

    Later,

    Dave

  • #2
    so looks like i just take power once from black box then jump from 1 track to the other,meanibg only a pos and neg line will be coming from black box ,connecting to first track,then wires from first track go to another track for jumping?

    Comment


    • #3
      I have a question, from what I understand is that you have to power the jumper thru the pitbox. how is this accomplished?

      Comment


      • #4
        Originally posted by Johnny Dingo View Post
        I have a question, from what I understand is that you have to power the jumper thru the pitbox. how is this accomplished?
        Ajack and Johnny,

        The idea is not as complicated as you are assuming. All that is being done is to transfer power from where the power has the least amount of loss (the terminal area) to an area that has the most loss (the furthest from the terminal that is the midway point).

        To better illustrate how these tracks would work on my next layout, here are a couple of TP diagrams of my new track coming in a month or so.

        This is the layout as is......





        .....and this is how the track looks w/ the top deck removed and showing the position of the jumper tracks.



        As you can see, nothing has been jumped to the Pit Box. The idea is to get the "power transfer track" as close as possible to the area where the main terminal (Pit Box) is located and from there run the "power receiver track" about half way through the layout. In this particular layout, it was nice to know that the mid point of the track happened to be about a foot away from the starting area and thus it will minimize clutter and distance for the power and data to transfer.

        Hope this helps to explain it better.

        Dave
        Last edited by LDFan; 07-23-2009, 04:50 PM.

        Comment


        • #5
          Thanks Dave, It's all crystal clear now. I am sure I will have to install jumpers on my layout. I started out with about 65' of track and added some last week to some were around 85 to 100' then I started to have power issues. Just a lack of power all around and eventually found what I think is a short in one of the wall wart cords so I haven't been able to test anything untill the new power supply arrives.

          Comment


          • #6
            Originally posted by Johnny Dingo View Post
            Thanks Dave, It's all crystal clear now. I am sure I will have to install jumpers on my layout. I started out with about 65' of track and added some last week to some were around 85 to 100' then I started to have power issues. Just a lack of power all around and eventually found what I think is a short in one of the wall wart cords so I haven't been able to test anything untill the new power supply arrives.

            Hey Johnny,

            Glad I was able to clarify it.

            Also, if and when you decide to take on the jumper, please make sure to take all possible precautions so that you don't burn out the Pit Box or Control Unit.

            A simple way to test if the system is properly wired would be to use a voltmeter on continuity mode and verifying that the rails are lined up right. In addition, when performing a live test, I would have two sets of tracks layed out in which they are connected with "only" the jumper. If a car runs properly on the remote track piece, then you have it correct. Also, test accessories like the Chrono on the remote section to see if data is transferred properly from one to another. I'll try and post pics later of how my test rig looks like.

            Dave
            Last edited by LDFan; 07-24-2009, 04:51 PM.

            Comment


            • #7
              SCX Digital Power Jumper Track Mod

              SCX Digital Power Jumper Track Mod

              SUGGESTION - Only;

              From my personnel past experience, I would “NEVER” permanently mount the slot track to the layout board,
              unless each individual piece of permanent track, had its own direct power supply.

              This is highly recommended, and a must in my “Digital” model train layout.

              Each track connection has a pressure type clip connection. In time the contacts will oxidize.
              Oxidizing will add more resistance, or no power contact.

              That is why our high quality electronics components, are gold plated.
              Electrical contact grease, may be of some use, to prevent some oxidation, at track contact clips.

              In time the top power rails will require cleaning, due to oxidization.
              This will also apply to the track contact power clips.

              If you are using a “permanent” mounted set –up,
              I would highly recommend track power feeder wires, to each individual track.
              Each track will receive uniform;
              1) 18 VDC (+) = Track Rail
              2) 18 VDC (-) = Track Rail
              3) Digital Signal = Hidden Bottom Rail

              This will always guarantee a good power supply, reducing any “dead spots”.

              Wires connected together, in a “series” connection (track to track), will help a lot.
              The problem with a series connection, it only takes one (x1) short, and the circuit is broken.
              I would recommend a (series - parallel) connection.
              This type of procedure will always ensure 100% direct power.

              -----------------------------------------------------------------------------------------

              NOTE: (as per LDFan)

              I would “permanently mark”, underneath the track, the correct track direction, to ensure the correct track direction.
              Correct polarity direction, is a must !

              - ED - Enjoy and have fun !!

              Comment


              • #8
                To protect against polarity goofs (so you can let your kids use any plugs you use).

                You could use plugs with 3 connectors...

                (+) (-) (+)

                Because both of the outter wires are +, the plug can be plugged in either way safely...
                You still only need a 2 wire line... just jumper the two + terminals at each end of the cord you make.

                This ignores the 3rd rail in SCX track that just powers the lights and accessories, on the assumption that the existing line is enough for those.

                Comment


                • #9
                  Originally posted by Draconious View Post
                  To protect against polarity goofs (so you can let your kids use any plugs you use).

                  You could use plugs with 3 connectors...

                  (+) (-) (+)
                  Actually, if you look closely @ the plugs I used, they are "notched" to prevent the wires from being reversed. Thus, the only trick to prevent any possibility of shorting is to ensure that everything along the way (e.g.: the wiring of the track, the direction of travel, and the pinning of the jumper cable) is just installed correctly to begin with.


                  This ignores the 3rd rail in SCX track that just powers the lights and accessories, on the assumption that the existing line is enough for those.

                  I concur that the jumping of the PowerLine itself is of limited use since none of the accessories really need to "perform" in any manner that is going to affect the outcome of the race. However, I had plugs that accepted three wires and most of the wire I had lying around had three as well. I didn't want it to go to waste.

                  On the other hand, jumping the PowerLine may help in a small way to ensure the accessories like the Digital Bridge do get adequate power to make the lights operate as optimally as designed (especially on the far end of the layout). But of course, it's more about looks than performance.


                  Dave

                  Comment


                  • #10
                    Acutally I guess what I typed above, wouldnt work if the track section was reversed, not sure why I thought it would work when I typed that...

                    Comment


                    • #11
                      SCX Digital Power Jumper Track Mod

                      SCX Digital Power Jumper Track Mod

                      SUGGESTION #2 - Only;

                      For present and any future SCX enhancements,
                      I would highly recommend connecting the “HIDDEN” center rail, to a power jumper system.

                      The SCX 25030 Lap Counter uses a three (x3) wire connection, from the track.
                      Since I do not have a SCX 25040 Chronometer,
                      I am quite sure that this will also have a three (x3) wire connection.

                      SCX will not disclose any private electrical information.

                      I am not advanced in digital wave signals, and I do not have an oscilloscope.
                      The center power rail, may also be a digital VDC rail.
                      -OR -
                      Just a simple power line.
                      Only SCX knows !
                      Who knows what present or advanced features may be used, for the center rail !

                      =========================
                      As per LDFan: (Credit)

                      -Great detailed pictures.
                      -IDE Molex Power Supply Cables.
                      -D plugs.
                      =====================

                      Presently I find that the molex “D” plugs, are actually quite expensive, for what you get.
                      Also limited in doing any custom connections. (Series – Parallel).
                      Molex “D” does have much better connections, and a thicker wire gage.

                      I have designed a much cheaper, more reliable set up.
                      A series – parallel, track feeder connections.
                      This can also be used for any temporary or permanent layout.

                      Digital Power Jumpers: (x5 Lines)
                      Purchase a standard, 5 Way Telephone Outlet Jack Adapter with Cord. (Splitter Box)
                      RJ-11 = 6P-4C (6 Poles - 4 Contacts).
                      This is a series – parallel, splitter box.
                      The “same colored wires” are connected together.
                      This will be used as the main “jumper module”.

                      SPLITTER BOX:
                      -All connections to a good direct power source
                      -Connect to “Track” of powered SCX Control Unit
                      -Use separate wires RED, Black, Yellow
                      -Solder wires (x3) to bottom of track
                      -Solder RED wire to the positive (+) rail
                      -Solder BLACK wire to the negative (-) rail
                      -Solder YELLOW wire to the center rail

                      Option #1: (Direct Connection)
                      -Cut off the male jack connector, from telephone adapter
                      -Solder wires (x3) to bottom of track

                      Option #2: (Adapter Connection)
                      -Use 4P-4C telephone flat wire
                      -Solder wires (x3) to bottom of track
                      -Attach a male jack connector (RJ-11)
                      -RJ-11 = 6P-4C
                      -Use Extension Adapters (x5) to connect cables

                      TRACK FEEDER LINES: (x5 Locations)
                      -My first choice would be the Lap Counter
                      -My second choice would be the Chronometer
                      -My third choice would be the “cross over” tracks
                      -My fourth choice would be the “long straight” tracks
                      -Very important, paint “track direction - arrow” on bottom of track
                      -Use 4P-4C telephone flat wire
                      -Solder wires (x3) to bottom of track
                      -Determine length of wires.
                      -Mount a male jack connector (RJ-11)
                      -RJ-11 = 6P-4C
                      -Attach cables (x5) to splitter box

                      =====================================

                      INFORMATION; (width, wires, connections)

                      P = Poles (width of actual connection)
                      C = Contacts (# of wires - connections)

                      4P-4C = Telephone - Hand set cable (4 wires)
                      6P-4C = Telephone - Lines (4 wires) RJ-11
                      6P-6C = Telephone - Lines (6 wires) RJ-12
                      8P-8C = Computer - Lines (8 wires) RJ-45

                      ====================================

                      CONCLUSION:


                      This is a simple and cheap way to add “Power Jumper Lines”, throughout the layout.
                      This being a series – parallel set up, will ensure better power to the track.


                      - ED - Enjoy and have fun !!

                      Comment


                      • #12
                        Hi all..... I have one question!

                        I tried to Solder wires (x3) to bottom of track:

                        -Solder RED wire to the positive (+) rail
                        -Solder BLACK wire to the negative (-) rail
                        -Solder YELLOW wire to the center rail

                        but in my track, i dont have the center rail??? its 2004 straight track.....

                        what i have to do??

                        tks....

                        Andre

                        Comment


                        • #13
                          This question would be better answered by the mods at scxworldwide.com. I did not jumper the powerline on my track, just the + and - rails. This should be enough for both digital or analog track.

                          Comment


                          • #14
                            I would just let it go. There is little reason to jumper the powerline as it only powers the accessories. You MUST install the items that directly use the powerline - the Lap Counter and the Chrono - within the bounds of the powerline or they will not work.

                            Comment


                            • #15
                              That is true that it's not necessary to jump the PowerLine especially if the accessories will be close to the Pit Box / Control Unit.

                              On the other hand, certain other accessories like the Digital Bridge also pull power from the PowerLine to run its lights and you may not have control of where you put it in the layout so that can affect how bright the lights will be (a minor nuisance that no one would be able to tell, except me ).

                              In any case, you can still tap that PowerLine on the newer track that has no metal strip under the slot (FYI: the new track has a wire running under the "outer track power rails" instead of the metal strip running under the slot).

                              To tap it (if you still want to), you would go here as the pic indicates.




                              And as to running the cable assembly, this is how I did it w/ the newer track.




                              Hope this helps.

                              Dave
                              Last edited by LDFan; 01-31-2012, 11:28 AM.

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