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"A DIGITRAX AR1 QUESTION"

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  • Member since
    December 2005
  • From: west of Portland Oreg.( the city of Roses
  • 549 posts
"A DIGITRAX AR1 QUESTION"
Posted by TrainsRMe1 on Tuesday, March 30, 2021 10:09 PM

CoolHI All

I have a question, on my reverse loop, I'm using a AR1 to reverse the polarity, I ran a test loco into the loop, and here's what happened, the loco caused a short and traveled the opposite direction,  could someone show me a diagram of a AR1?? I want to see if I wired it correctly, or I might have a bad AR1.

THANKS GUYS N GALS!!Wink

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 19,777 posts
Posted by MisterBeasley on Tuesday, March 30, 2021 10:24 PM

Is this a DCC locomotive operating on a DCC system?  I have seen similar behavior test-running a DC engine in DC mode on my DCC system.

An AR-1, like all auto-reversers, will only work on a DCC system.

It takes an iron man to play with a toy iron horse. 

  • Member since
    December 2005
  • From: west of Portland Oreg.( the city of Roses
  • 549 posts
Posted by TrainsRMe1 on Tuesday, March 30, 2021 10:44 PM

I ran an analog loco first, I do have four DCC locos, I'll test my DCC locos, would my Big Boy have problems,  it's DCC equipped.??

  • Member since
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  • From: Dearborn Station
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Posted by richhotrain on Wednesday, March 31, 2021 5:45 AM

Is your layout DC or DCC?

Rich

Alton Junction

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    June 2020
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Posted by Lastspikemike on Wednesday, March 31, 2021 9:00 AM

Reverse loops powered by DC are wired opposite to those wired for DCC, in effect. They are wired the same but the reversing effect is opposite.

DCC locomotives control their own direction by decoding the DCC signal. DCC are smart locomotives. The decoder decides which DC polarity to feed to the motor. But only when running in DCC mode.

DC locomotives are not that smart. They change direction with the track polarity. Dual decoder DCC locomotives revert to dumb mode when they receive DC power from the rails. Without a DCC signal the brainy part of the decoder is basically disabled.

Because DCC does not "reverse polarity" to change locomotive direction the reversing wiring can change the polarity inside the reversing loop or outside, it doesn't affect the locomotive direction.  Because of the possibility of current draw outside the reversing loop being much higher than within the reversing loop most DCC layouts reverse rail power phase (DCC equivalent of the DC powerpack reversing switch) inside the loop where only one set of locomotives will generally be running. But that is arbitrary. It works either way. Autoreversers reverse power phase throughout the layout that booster is powering. DCC locomotives don't care about phase as long as the phase matches correctly for each rail. Phase reversal doesn't faze a decoder equipped locomotive, they keep on going.  

For DC reversing loops the polarity is only reversed outside the reversing loop and only after the entire train is within the loop. Any locomotive operating on the main line will reverse direction including all the DCC dual decoder equipped locomotives that are running in DC mode. 

Your DC powered locomotive is reversing the entire layout polarity (not the rail power phase) when it trips the auto reverser with its lead axle. The locomotive naturally changes direction.

It doesn't matter whether the locomotive is decoder equipped because it is running in DC mode. You can't use a short circuit type auto reverser in a DC powered circuit. You can use optical types.

Alyth Yard

Canada

  • Member since
    December 2005
  • From: west of Portland Oreg.( the city of Roses
  • 549 posts
Posted by TrainsRMe1 on Wednesday, March 31, 2021 10:55 AM

My layout is DCCCool

  • Member since
    December 2005
  • From: west of Portland Oreg.( the city of Roses
  • 549 posts
Posted by TrainsRMe1 on Wednesday, March 31, 2021 11:03 AM
It's DCC
  • Member since
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  • From: Dearborn Station
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Posted by richhotrain on Wednesday, March 31, 2021 11:04 AM

TrainsRMe1

My layout is DCC 

Well, that is weird then if it was a DCC loco on your DCC layout. There would be no reason for the loco to go in the opposite direction. I have had AR-1 auto-reversers on my DCC layout, and that never happened.

Was it a DC loco that performed that way?

Rich

Alton Junction

  • Member since
    December 2004
  • From: Bedford, MA, USA
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Posted by MisterBeasley on Wednesday, March 31, 2021 11:16 AM

TrainsRMe1

I ran an analog loco first, I do have four DCC locos, I'll test my DCC locos, would my Big Boy have problems,  it's DCC equipped.??

If you used an analog DC engine on a DCC system, that's probably the result you would get.   A DCC engine should work properly.

It takes an iron man to play with a toy iron horse. 

  • Member since
    December 2015
  • From: Shenandoah Valley
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Posted by BigDaddy on Wednesday, March 31, 2021 11:32 AM

If we had some understanding of your previous problem, where there was a short in the return loop, we might be able to give better advice

Henry

COB Potomac & Northern

Shenandoah Valley

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Posted by hornblower on Wednesday, March 31, 2021 2:29 PM

I use Digitrax AR1 reversers on my DCC layout and they all work as designed.  However, I never run analog locos on my DCC layout. Since your layout is already DCC powered, I would recommend converting all of your DC analog locos to DCC as soon as possible. If your budget is getting in the way, the NCE D13 decoder is pretty cheap and quite reliable (no sound though).  They are not hard to install and most analog locos don't require much, if any, work to isolate the motor.  

Hornblower

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Posted by mfm37 on Wednesday, March 31, 2021 5:08 PM
Your AR1 worked perfectly. It changed the phase to match that of the adjacent track to correct the short and your DC (analog) engine reversed because the (polarity) was now reversed. If you were powering the track with analog DC, the AR1 would do the same except each time the DC engine reversed across the gap, the short would re-occur. Auto reversers won't work properly with analog engines even when using address 00.

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