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Electrical Feedback Problem

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  • Member since
    February, 2005
  • From: WNY
  • 86 posts
Electrical Feedback Problem
Posted by ACRR46 on Saturday, March 22, 2008 5:10 PM

I recently completed attaching feeders to the two main 14 gauge buss wires.  Since my new Digitrax Super Chief system is located near the center of my layout my buss wires from the left and right meet at terminal strips.  From the terminal strip I run two 14 gauge wires to the Rail A and Rail B conections on the Digitrax unit.  The system is not connected to the transformer or power scource.

 To test my wiring I built a buzzer powered by a double AA battery.  By touching the test leeds to my black buss wires is buzzes.  I did the same with the red buss wire. 

 Much to my surprise when I touch the black wire connections at the terminal strip to the red buss wire terminal strip I hear a very faint buzz or scratchy sound.

My next test was to disconnect all busses and test the Power A an B connections on the Digitrax Control System. I was surprised when touching both connections they also made a faint buzzing sound.  Is that a problem?

 I'm at a loss how to solve my problem.  Any suggestions would be appreciated.

ACRR46

 

 

 

  • Member since
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  • 385 posts
Posted by UpNorth on Saturday, March 22, 2008 5:51 PM

The way  I  understand your note ( or it may not be clear enought )  this is not a problem.

Your simply putting 3V  into the  Super Chief  rail A, B and the internal resistance of the unit  is what causes the faint buzz. Don't do this too often thow.  Or I fail to undestand some of your testing  methods. 

  • Member since
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  • From: Charlotte, NC
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Posted by Phoebe Vet on Saturday, March 22, 2008 6:04 PM

For what possible reason would you put voltage from an outside source across the track leads of a digital controller?

What, exactly, do you think you are testing for?

If you are testing for shorts in your buss, DISCONNECT the controller, remove all powered or lighted stock from the track, and anything else that draws power from the buss, and then test the buss for shorts.

For less than the cost of a battery and a buzzer you could have bought a cheap multimeter.

Why are you testing, anyway?  Isn't it working?  What problem are you trying to diagnose?

Dave

Lackawanna Route of the Phoebe Snow

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Posted by john galt on Saturday, March 22, 2008 6:17 PM

i agree.. how about maybe, if you dont connect a speaker/buzzer you wont hear it.  unless it is feeding thru your engine speakers??? so what exactly is your problem?

 

  • Member since
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  • From: WNY
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Posted by ACRR46 on Saturday, March 22, 2008 6:44 PM

I guess I did not explain my problem clearly. All I'm trying to do is test my buss wires.

If I touch black to black or red to red buss wires I the buzzer beeps. 

However if I should touch a black to red buss wire I hear a faint buzzer sound, which to means I have a problem, but I don't see any crossed feeder wires.

 

  • Member since
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  • From: Vail, AZ
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Posted by Vail and Southwestern RR on Saturday, March 22, 2008 6:58 PM

The relevant question is whether the command station is hooked to the bus.  If so, unhook it and go again.  As someone else said, I think you are seeing the resistance of the command station.  You don't want to put power on the bus while it is connected to the command station.

 

Jeff But it's a dry heat!

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  • From: Orig: Tyler Texas. Lived in seven countries, now live in Sundown, Louisiana
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Posted by jeffrey-wimberly on Saturday, March 22, 2008 7:15 PM
As stated above, make sure the wires are disconnected from the command station, also make sure that there's nothing on the track and I mean NOTHING. I was testing my layout one time with a multi-meter to see if I had a short anywhere and it kept showing a dead short. I checked the wires I don't remember how many times then was checking the track to see if a tool was shorting rails outs when I saw it, a small 4 wheel switcher that my nephew had been messing around with was on a spur. I removed it and there was no more short.

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  • Member since
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  • From: Charlotte, NC
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Posted by Phoebe Vet on Saturday, March 22, 2008 7:47 PM
 ACRR46 wrote:

I guess I did not explain my problem clearly. All I'm trying to do is test my buss wires.

If I touch black to black or red to red buss wires I the buzzer beeps. 

However if I should touch a black to red buss wire I hear a faint buzzer sound, which to means I have a problem, but I don't see any crossed feeder wires.

 

 

I repeat:

If you are testing for shorts in your buss, DISCONNECT the controller, remove all powered or lighted stock from the track, and anything else that draws power from the buss including any loconet devices or sensors that are connected to the track or the buss, and then test the buss for shorts.

Digitrax controllers are short circuit protected.  Turn it on.  If you have a short anywhere, it will trip and beep.

Dave

Lackawanna Route of the Phoebe Snow

  • Member since
    January, 2001
  • From: Kansas
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Posted by jamnest on Saturday, March 22, 2008 8:37 PM

I agree with the others, you should not be putting a current on the wiring buss with your command station connected.

You have a Digitrax DCS-100 command station.  If you power up your command station and there is a short in your wiring, your command station will beep three times and shut down until the short is removed. I would not use this method to test your wiring.  Get a multi meter.

Jim, Modeling the Kansas City Southern Lines in HO scale.

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    February, 2008
  • 385 posts
Posted by UpNorth on Sunday, March 23, 2008 12:59 AM
 ACRR46 wrote:

I guess I did not explain my problem clearly. All I'm trying to do is test my buss wires.

If I touch black to black or red to red buss wires I the buzzer beeps. 

However if I should touch a black to red buss wire I hear a faint buzzer sound, which to means I have a problem, but I don't see any crossed feeder wires.    

I'm certain you will get to the bottom of it. Start over.

  • Member since
    October, 2004
  • From: Colorful Colorado
  • 8,639 posts
Posted by Texas Zepher on Wednesday, March 26, 2008 8:06 PM

 ACRR46 wrote:
To test my wiring
To test it for what, continutity, shorts, current draw????

test the Power A an B connections on the Digitrax Control System. I was surprised when touching both connections they also made a faint buzzing sound.
Why were you surprised, you are feeding power into an electronic device "backwards" anything can happen?

Is that a problem?
It could be hard on your Super Chief unit.

I'm at a loss how to solve my problem.
I don't think you have a problem.  Why don't you connect the Super Chief to the bus and test in a normal way.  Put a locomotive on the track and see if it gets power and runs?

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