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Decoder troubleshooting

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  • Member since
    May 2008
  • 16 posts
Decoder troubleshooting
Posted by TimmyMWD on Monday, December 29, 2008 10:16 AM

 Hey all,

 I'm pretty new to DCC, so I'm hoping you can back up my diagnosis.  I just got a second Athearn Dash 9 for my layout off of ebay.  Engine is in fine shape and runs great.  I'm having problems with DCC; however.  It will run fine on the address the seller told me it was assigned to - but it won't consist at all and won't accept reprogramming.  Little things are weird too - my other Athearn Dash 9 flips its lights depending on which direction its going, but this one won't for example.  I'm guessing I should just drop $10 and get a new decoder, would that be the best way to go?

 Thanks!

 -Tim

  • Member since
    July 2003
  • From: Sierra Vista, Arizona
  • 13,757 posts
Posted by cacole on Monday, December 29, 2008 10:18 AM

 Are you sure it even has a DCC decoder?  If so, it will probably be an MRC product, which is extremely unreliable and practically impossible to program.  I've now had 6 out of 7 MRC decoders that were dead on arrival.

Are you attempting to reprogram the decoder on a programming track or main line (Ops Mode).  If you can't change the decoder using Ops Mode, it is probably defective.  You need a acquire the documentation for the brand and type of decoder that is in the engine in order to know how to change the lighting function CVs.  If it's MRC, it probably can't be changed.

Your first step should be to open up the locomotive and find out what brand and type of decoder it has, then go to that manufacturer's web site and download the instruction manual for the decoder.

If you have a DCC system that can read CV values, query CVs 7 and 8, which will give you a value that identifies the manufacturer and version number of the decoder (unless it's an MRC, which doesn't provide feedback.)  Then go to the NMRA web site and download their index of manufacturer numbers.

  • Member since
    May 2002
  • From: Massachusetts
  • 2,899 posts
Posted by Paul3 on Monday, December 29, 2008 10:28 AM

We need to know what kind of decoder is in there, and what kind of DCC system are you running in order to give out correct info.

If you want to replace the decoder, the question is what kind of lights do you want?  If you want working ditch lights, then you'll need something fancy like the $26 Digitrax DH163D.  If you just want headlights fore and aft, then a cheaper decoder like a $16 DH123D would do.  The "D" versions are "hardwire" jobs that normally require soldering and a little elbow grease.  However, your current decoder may have a plug in it that would make replacement a snap.

BTW, headlights that are directional are normal in DCC.  That your engine doesn't mean that it's been programmed for that.

Paul A. Cutler III
*******************
Weather Or No Go New Haven
*******************

  • Member since
    May 2008
  • 16 posts
Posted by TimmyMWD on Monday, December 29, 2008 11:49 AM

I'm sure it has a DCC decoder because I had to plug in its address (0033) to get it to run.  It was a digitrax decoder, but I'm not sure which (I'm out of town at the moment).  The engine has the quick plug which requires no soldering (yay!  I've learned to despise soldering with a burning passion), which should make whatever solution I end up taking a little bit easier.

 When I get back in town tomorrow I'll pop open the shell and see what the model # is on the decoder.

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Monday, December 29, 2008 12:49 PM

 Sounds like the seller configured the decoder lock so the programming can't be changed. Try reading CV16 and then setting CV15 to whatever value you read from CV16.

                            --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Tuesday, December 30, 2008 12:55 AM

 However if it's locked, it won't reset.

                --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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