I just installed a Digitrax DH123PS DCC decoder into an Atlas HO MP15DC engine and when I power up the engine it runs backwards when I tell it to run forward, and it runs forward when I tell it to run backwards. Do I just have to flip the 8 pin socket around or do I have to resolder the motor wires differently? If I just have to turn the 8pin socket around I am not sure I have enough wire length to make the decoder fit properly where it has to go as I only have the 1 1/2" wire harness.
Does the light follow the direction?
Did you wire according the NMRA recommendations or did the decoder come attached to the plug? If it came all together, reverse the plug. You just plugged it in wrong.
There is a CV to handle this in the decoder CV list. The Digitrax website has the CV list.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
If you have the plug on the decoder oriented so that pin #1 (orange wire) is plugged into pin #1 on the socket (usually a small arrowhead in Atlas locos), then you have the decoder installed correctly.
Once you've confirmed that, if it still travels in the "wrong" direction, use CV29 to reverse the NDOT.
Oh, and sometimes to get it plugged in correctly and still enable the decoder to fit, you have to fold the wiring harness over on itself to get the decoder pointing in the opposite direction. In that case, yes the PS harness might well be too short. If it is, just replace it with the long harness:
http://www.digitrax.com/products/mobile-decoders/dhwhp/
It may not even be your fault. The pick up wires from the trucks could have been reversed at the factory, this happened to me on one of my locos. Either reverse the wires to the motor or change CV29. If the 8 pin plug is backwards, your front headlight probably won't work.
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And I've done some early Proto2000 installs where they used a red wire for motor- and black wire for motor+ just the opposite of what I would expect.
So, using JMRI DecoderPro I simply selected N ormal D irection O f T ravel to reverse and everything was Hunky Dory!
Ed
Thanks everyone for all the help! I really appreciate it. It turns out the 8 pin plug was in backwards. I was able to get a longer wire harness and everything works great now. Thanks so much for your help!