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Power Pack Short ?

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  • Member since
    February 2003
  • From: New Jersey, US
  • 379 posts
Power Pack Short ?
Posted by topcopdoc on Monday, August 17, 2009 3:18 PM

After adding five new storage tracks and six new turnouts I found I had a short across the tracks. I got out my trusty VOM meter and checked everything. I took every thing apart and cut the rails to the main line and followed the short circuit back to the DC power pack. 

 

 I get continuity across the variable DC connecting screws even when it is not plugged in. I checked another power pack and had no continuity on the meter. Would I be correct thinking that the power pack is faulty? It runs the trains okay. 

 

Doc

 

Pennsylvania Railroad The Standard Railroad of the World
  • Member since
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  • From: Western, MA
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Posted by richg1998 on Monday, August 17, 2009 4:08 PM

Continuity has to do with resistance, not voltage. There will be DC voltage if the pack is plugged in and the direction switch is in forward or reverse. Unplug and there will be resistance using the ohm meter selection with the direction switch in forward or reverse.

What is the actual resistance reading you measure?

The second pack may be in center, no direction selected or a defective pack. If the pack hums, and is quite warm, you would probably have a short if the circuit breaker did not trip. What are the brands of pack's?

This is a little confusing. Which one runs the trains just fine?

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

  • Member since
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  • From: New Jersey, US
  • 379 posts
Posted by topcopdoc on Monday, August 17, 2009 6:00 PM
The Power Pack is a “Spectrum” which seemed to run a test loco around the tracks okay. As a last step to see if there were any shorts or dead spots I checked with a VOM meter and found continuity between both rails. Nothing was found shorting the rails except the “Spectrum” power pack. 

 

The VOM meter on 1 ohm reads 50 on the variable connecting screws on the power pack while the unit is off and unplugged. A check of a “Railpower” power pack reads 0 under the same conditions.

 

 Doc

 

Pennsylvania Railroad The Standard Railroad of the World
  • Member since
    September 2007
  • From: Charlotte, NC
  • 6,099 posts
Posted by Phoebe Vet on Monday, August 17, 2009 6:11 PM

You can't check your new track for shorts with the power pack attached, even turned off.

Disconnect the power pack, remove all powered or lighted stock from the track, disconnect anything that is getting it's power from the track, and then check the track for shorts.  If you find the track shorted start removing the new track you just added,one piece at a time until the short is gone.

You probably created a reverse loop or shorted switch when you added the new track.

With a diagram of the old and new, we can probably see where it is.

On a simpler note.  Make sure you haven't left a tool on the track somewhere.

Dave

Lackawanna Route of the Phoebe Snow

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  • From: Charlotte, NC
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Posted by Phoebe Vet on Monday, August 17, 2009 6:14 PM

After reading your second post I am confused.  If you can run a train on the track why do you think it has a short?  If it had a short the train would not run.

Dave

Lackawanna Route of the Phoebe Snow

  • Member since
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  • From: Western, MA
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Posted by richg1998 on Monday, August 17, 2009 8:07 PM

Without nothing connected to the packs, put your VOM on DC volts. Connect the meter to the track terminals on the pack. Plug in the pack, turn the pack on, switch to forward or reverse. Turn up the speed. The voltage should vary as you vary the control. No reading would mean the pack is no good. It could be shorted and it would heat up, a circuit breaker or fuse is open, defective connection in the pack.

With nothing on the track, there should be no resistance indicated on the VOM when measuring between rails.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

  • Member since
    September 2007
  • From: Charlotte, NC
  • 6,099 posts
Posted by Phoebe Vet on Monday, August 17, 2009 8:22 PM

richg1998

Without nothing connected to the packs, put your VOM on DC volts. Connect the meter to the track terminals on the pack. Plug in the pack, turn the pack on, switch to forward or reverse. Turn up the speed. The voltage should vary as you vary the control. No reading would mean the pack is no good. It could be shorted and it would heat up, a circuit breaker or fuse is open, defective connection in the pack.

With nothing on the track, there should be no resistance indicated on the VOM when measuring between rails.

Rich

You are in error.  With nothing on the track there would be infinite resistance.  No resistance would be a short.

Dave

Lackawanna Route of the Phoebe Snow

  • Member since
    October 2006
  • From: Western, MA
  • 8,571 posts
Posted by richg1998 on Monday, August 17, 2009 8:54 PM

 Yes, I was thinking infinite and wrote no. My mistake. Thanks for the corection.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

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