+ and - decoder connections

Discussion in 'DCC & Electronics' started by Woodie, Dec 26, 2005.

  1. Woodie

    Woodie Active Member

    I understand the standard decoder connections and what they're for. The red & black are quite easy to determine how they're connected. (left & right track pickup). However the grey and orange are the + and - connections of the motor. This will determine which direction the loco goes in "forward" (or "reverse").

    Is there an easy way of determining what connection to the motor is + and which is -, other than trial and error? What method do you use, if any?

    3 out of the 4 decoders I've put in so far, I've had to reverse the grey/orange connections to get the right direction of movement. I just made a guess as to which was + and which was -, as I can't think of an easy way of determining this.
  2. LisaP4

    LisaP4 New Member

    Check out the wiring before fitting the decoder, the motor pole that was connected to the right rail should take the orange lead, and likewise the pole that was connected to the left rail takes the grey lead. Of course there's always the occassional loco that want's to be differant and not follow the rules, but it should be correct 9 times out 10.

    Red and black to the track, orange and grey the other way.
  3. 60103

    60103 Pooh Bah

    Woodie: there should be a CV in the decoder that that says "run the loco backward" or words to that effect. This lets you tell the decoder to run the loco the other way when you say forward. It's useful if you set, say, two powered diesels back to back. Or you decide to run your Geeps long hood leading.
  4. Gary Pfeil

    Gary Pfeil Active Member

    I believe that would be cv29, you add 1 to whatwever value is there and it changes normal direction of travel. As David said, it is great for running locos such as a GP7 long hood forward, like the NYC did, and several other roads. Not only does it change the direction, it also makes the headlight at that end light when going forward. Which may be a problem when using this cv to correct incorrectly wired motor leads, the wrong headlight may light! Tho I am not sure of this. But I do think it is best to get it right. I've always done mine trial and error, testing before soldering. I wasn't aware of what LisaP4 mentioned, great info, thanks!

  5. Woodie

    Woodie Active Member

    Thanks David for that. Yep. On mine, it's the "reverse bit" in the decoder config. However I wanna run them configed and installed to the main defaults and wiring if I can.

    When you run a cuppla these, it's pretty arbitrary which is the front end anyway. :) :cool:


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