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P2K SW9 Acting Strange

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  • Member since
    June 2006
  • From: Baltimore, MD
  • 1,726 posts
P2K SW9 Acting Strange
Posted by CSX_road_slug on Friday, July 18, 2008 4:47 PM

I have a Proto2000 HO-scale SW9 equipped with the NCE SW9-SR decoder, and it "jumps" ~1 inch whenever power is first applied to it.  If this only happened when I energize the track, I could live with that; but it does the same thing if it rolls over a spot where input voltage may be a bit weak (such as an insulated-frog turnout).  And sometimes it jumps in the opposite direction from where it's supposed to be moving.  Seems as if something is dropping a full-strength jolt across the motor leads!  Needless to say, this is a major annoyance during switching operations and coupling/uncoupling.

Does anybody have a clue why the decoder would make it behave this way, and what might be done to correct it (other than installing a new decoder)?

 

-Ken in Maryland  (B&O modeler, former CSX modeler)

  • Member since
    August 2007
  • From: Maryland
  • 178 posts
Posted by mikebo on Friday, July 18, 2008 6:04 PM

I don't have an answer but I have found that having an RRampmeter connected to my layout generally gives me a better idea of what is happening.  For example, If the current draw is increasing when the loco jumps, generally means a short or bind in the mechanism. 

The only time I've seen a loco change direction on it's own was when running a DCC loco in DC mode. Every time it hit an insulated frog, it reversed.

Mike Modeling Maryland Railroads in the 60's (plus or minus a few years)
  • Member since
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Posted by locoi1sa on Friday, July 18, 2008 6:37 PM

  Ken

 What DCC system are you useing? Disable analog in CV29 first. Second make sure the mechanisim is working good. Maybe its binding or needs lube.

    Pete
 

 I pray every day I break even, Cause I can really use the money!

 I started with nothing and still have most of it left!

  • Member since
    June 2006
  • From: Baltimore, MD
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Posted by CSX_road_slug on Friday, July 18, 2008 10:50 PM

 davidmbedard wrote:
Check to see if you have the DC conversion diabled.

OK, I disabled it by setting CV29=034.  That appeared to solve the problem - for about 1 minute, until the loco stopped responding to any commands at all... Confused [%-)]

 davidmbedard wrote:
Check to see if there is a slight short between the motor and the track leads.
(Wiring was OK)

 davidmbedard wrote:
Try a decoder reset.

I followed the reset instructions in the NCE manual, by setting CV30=002.  This did indeed reset the CVs - but not to factory defaults, it changed every one of them to 255!

I think I must have fried the decoder at some point...Dead [xx(]

 

-Ken in Maryland  (B&O modeler, former CSX modeler)

  • Member since
    June 2006
  • From: Baltimore, MD
  • 1,726 posts
Posted by CSX_road_slug on Friday, July 18, 2008 10:52 PM

 locoi1sa wrote:
 What DCC system are you useing? Disable analog in CV29 first. Second make sure the mechanisim is working good. Maybe its binding or needs lube.

Digitrax Super Chief (DCS100+DT400R) 

-Ken in Maryland  (B&O modeler, former CSX modeler)

  • Member since
    June 2006
  • From: Baltimore, MD
  • 1,726 posts
Posted by CSX_road_slug on Friday, July 18, 2008 10:54 PM
 mikebo wrote:

... The only time I've seen a loco change direction on it's own was when running a DCC loco in DC mode. Every time it hit an insulated frog, it reversed.

Yeah, I've had that happen to me as well, before I connected the DSC100 to the layout.

-Ken in Maryland  (B&O modeler, former CSX modeler)

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