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decoder problem

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  • Member since
    March 2005
  • From: New Brighton, MN
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decoder problem
Posted by ARTHILL on Wednesday, February 13, 2019 12:40 PM

I put a decoder in an old brass engine.It works but goes back in forward. The forward light also comes on in reverse. Do I fix this with my programing track or do I have to reverse to wires? if so, which ones? It has been a while and I have forgotten most of what I used to know about these thngs.

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  • Member since
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Posted by AlienKing on Wednesday, February 13, 2019 1:43 PM

You could fix it either way, but I think changing the CV would be easier. To change it on the programming track, you need to flip bit 0 on CV 29. 0 is normal, 1 is inverted.

 

To figure out what the full value should be for CV29, first read it back.  If its even, add 1.  If its odd, subtract 1.

  • Member since
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  • From: Shenandoah Valley
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Posted by BigDaddy on Wednesday, February 13, 2019 2:52 PM

Or you could switch the wires that go from the decoder to the motor.

Henry

COB Potomac & Northern

Shenandoah Valley

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  • From: New Brighton, MN
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Posted by ARTHILL on Wednesday, February 13, 2019 3:11 PM

Would switching motor leads also get the headlight to go with forward?

If you think you have it right, your standards are too low. my photos http://s12.photobucket.com/albums/a235/ARTHILL/ Art
  • Member since
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  • From: lavale, md
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Posted by gregc on Wednesday, February 13, 2019 3:31 PM

i thought the LEDs were clearly marked for forward and reverse.   The motor leads are bit ambiguous which is why there is a CV to change the motor polarity.   I wouldn't expect the CV to also reverse the functions of the LEDs

greg - Philadelphia & Reading / Reading

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  • From: Shenandoah Valley
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Posted by BigDaddy on Wednesday, February 13, 2019 3:52 PM

Assuming the forward headlight is soldered to blue and white and you haven't messed with CV 29, the headlight is coming on when the engine should be moving forward.  It is the motor that is confused and changing motor leads will put the engine direction in sync with the headlight.

 

Henry

COB Potomac & Northern

Shenandoah Valley

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Posted by SouthPenn on Friday, February 15, 2019 10:43 PM

Changing the CV should also fix the lighting problem. 

Check page 34 in this manual.

South Penn
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Posted by AlienKing on Saturday, February 16, 2019 8:53 AM

CV 29 bit 0 defines the Normal Direction of Travel for an engine.  Usually you would use this when you want to set a diesel to run longhood forward by default.  It swaps both the engine direction and the lighting direction.

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  • From: Shenandoah Valley
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Posted by BigDaddy on Saturday, February 16, 2019 9:36 AM

AlienKing

CV 29 bit 0 defines the Normal Direction of Travel for an engine.  Usually you would use this when you want to set a diesel to run longhood forward by default.  It swaps both the engine direction and the lighting direction.

I'm having a hard time wrapping my head around this for 2 reasons.

1) I did what the OP did and while it's possible I screwed up reprogramming CV 29, it didn't work for me. 

2) I just spent 20 minutes reprogramming a correctly wired engines and running them forward and backwards and trying to puzzle it out.  If the change affects both motor and light, (and it does) but the OP only has the motor wired backwards, doesn't the OP's problem persist? 

Henry

COB Potomac & Northern

Shenandoah Valley

  • Member since
    April 2008
  • 113 posts
Posted by AlienKing on Saturday, February 16, 2019 9:51 AM

ARTHILL

I put a decoder in an old brass engine.It works but goes back in forward. The forward light also comes on in reverse.

BigDaddy

2) I just spent 20 minutes reprogramming a correctly wired engines and running them forward and backwards and trying to puzzle it out.  If the change affects both motor and light, (and it does) but the OP only has the motor wired backwards, doesn't the OP's problem persist? 

 

 

OP's lights are also working opposite.

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Posted by SouthPenn on Saturday, February 16, 2019 10:10 AM

All the work is done for you in the chart on page 34 of this Digitrax manual.

South Penn
  • Member since
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  • From: Collinwood, Ohio, USA
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Posted by gmpullman on Saturday, February 16, 2019 11:53 AM

SouthPenn
All the work is done for you in the chart on page 34

And easier yet is this CV calculator:

http://www.digitrax.com/support/cv/calculators/

Good Luck, Ed

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