Loco shorting out

Discussion in 'DCC & Electronics' started by eric halpin, Apr 6, 2007.

  1. eric halpin

    eric halpin Eric Halpin


    I hope you don't mind me posting regular (daily) questions in this forum but I am trying to get our new layout up and running on Digitrax DCC and we are having problems. Todays question is this. Before we hooked up the DCC we made sure the layout ran ok on DC except for the reverse loops. My Spectrum 2-8-0 ran like a charm on DC as did other DC locos. Once we ran changed over to DCC we ran our DC locos as per the DCC directions and they went fine except for my 2-8-0! For some reason, it causes a short on that section when placed on the track. Can this be readily explained?
  2. Gary Pfeil

    Gary Pfeil Active Member

    I'm not sure what you're saying, You say it causes a short on that section when placed on the track. Are you talking about the reverse loop, or anywhere? I installed decoders in mine so long ago I do not remember specifics, but there may be a capacitor on the pcb which is there to eliminate noise, required I believe in Europe. It causes problems with DCC, so just cut one of its legs, you don't need it and could cut both legs and discard if you wish. If the short is only when the loco enters a reverse loop, tell us what reverse module you are using.
  3. eric halpin

    eric halpin Eric Halpin


    The loco shorts the DCC section(s) where ever it is placed including the reverse loops!! This loco has not even had its DCC decoders installed yet, even though I have connected the wires and plugs from the loco to the tender. Since it ran great on DC why the sudden change when we changed over to DCC? Other DC locos run ok on the DCC track. Thanks for your assistance.
  4. pgandw

    pgandw Active Member

    From the information given, it appears the "short" is caused by one of 2 things:

    1) (less likely) a capcitor installed for interference filtering needs to be removed

    2) an internal (in the locomotive and/or tender) short circuit was introduced when connecting wires and plugs were hooked up


    Put the locomotive - exactly as is - back on the DC section of the layout with some decent short circuit detection. Do you get a short now? If yes, indicates a short introduced by the wiring changes. If no, means the filtering capacitor is the more likely culprit.

    Remote trouble-shooting is often hampered by lack of critical information that would give clues. Is there a filtering capacitor factory-installed? Is there a jumper plug where the DCC decoder will attach? Does this plug need to have its position changed to operate on DCC? Is the motor making any noises ("singing") in DC mode on DCC?

    yours in trouble-shooting
  5. eric halpin

    eric halpin Eric Halpin

    great info. I shall check it out. Many thanks
  6. eric halpin

    eric halpin Eric Halpin

    Today, I placed the loco back on DC track and it runs great. However, when replaced onto DCC track it immediately indicates a short !! I then disconnected the DCC plug from loco to tender with the same results! Before taking it appart, I have just written Bachmann for their opinion on this issue. I recall reading that some locos do not have their motors isolated from the frame and this must be done for DCC. If that is true maybe that is the problem? Will advise.
  7. rogerw

    rogerw Active Member

  8. pgandw

    pgandw Active Member

    Sounds like a real possibility, given your findings. Hope you can isolate the motor fairly easily. Watch out for metal mounting screws, Kadee offers nylon replacements.
  9. eric halpin

    eric halpin Eric Halpin

    Thanks Roger, I think we are on to something here!
  10. MasonJar

    MasonJar It's not rocket surgery


    I have a recent incarnation of this engine, and did not experience any of these problems. It ran fine on the DCC track on address "00", and also with the decoder in place. Installation was simply removing the jumper and plugging in the decoder (Digitrax).

    I know this may not sound like good news to you, but it may mean that you are looking for something more "unusual" as the problem, rather than the way (all) the locos are built...

    Hope that helps.

  11. eric halpin

    eric halpin Eric Halpin


    As per my earlier description of the short problem with the Spectrum 2-8-0, it has been a long haul but the solution was eventually solved, I think. I returned it to the retailer to get his opinion on what was wrong. They found nothing and said it ran fine on both DC and DCC (with their decoder installed). So I try it again on my layout with the same shorting problem. One of my railway partners found a web site from the 'Saskatoon Railroad Modelers' and they had a great article on installing decoders on this same engine. The info on there site led me to believe that I had purchased the first iteration of this loco by Bachmann (they have three). The first is faulty in that it operates in DCC very erratically. I had to cut the 'C1' capacitor on the board and once this was done the loco ran great. Details of this capacitor problem can be found on their web site and it is worth a read.

    So now I have a fine running Spectrum 2-8-0 on DCC! But the story is not over! I installed as per simple instructions the Soundex 'light steam' decoder and .5 ohm oval speaker. Unfortunatly, I can get no sound out of this beast. I have programmed the relevant CVs at about half full value (100/255).

    I don't understand DCC enough to do much more with this so I may be inclined to seek help from someone in my railroad club (OVAR). Wish me luck.

    But the model railway (Algoma and Rideau) is coming along nicely.
  12. MasonJar

    MasonJar It's not rocket surgery


    I am sure that someone from OVAR will be able to help you. Send me an email or PM (click on my user name for options) and we can figure it out.

  13. eric halpin

    eric halpin Eric Halpin

    2-8-0 sound problem


    Thanks so much but I went to Cornwall the other night for the Mohawk meeting (great group of guys) and Jacques T told me my problem was likely that I had not put the speaker in any kind of sound box. He says that without this box, the speaker will NOT provide any sound. So I shall build a box shortly and try that. I usually sit at the Bytown table at OVAR, so feel free to introduce yourself. Many thanks for your help.

  14. wickman

    wickman Member

    If your refering to this yellow capacitor , yes I've had to cut them off all of my spctrum steam engine's or at least most for them to run on the dcc. I wish I would have seen your thread problem earlier.
    You have to watch the Bachmanns , there notorious for being very inconsistant with there wiring, I've had to rewire 2 of mine after ringing out the wires and finding one was actually grounding. This was before I installed a tsunami sound decoder luckily.

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