Large Scale Central

Track power short problem

Electronics Power and Sound
#1

I’m having a problem with a short somewhere on the track I’ve recently laid. First some background.
We’ve moved to a new location, so I’ve decided to go from track power with a TE to track power & TMCC. I’m using the Lionel base & remote, but I’m using the boards from Train America Studios for my LGB & USA locos. Lionel SC-2’s control my LGB switch machines. I decided on the TAS/TMCC combo after a lot of research into DCC (didn’t like the prices & with the TAS boards I can control coil couplers on any loco or car).
I laid the track from my storage shed out beyond my 1st passing siding & up to the entrance to the main yard. After wiring the turnouts & running power to the track, I tested with an LGB loco. Everything worked fine, with full control of all functions of the TAS board in the loco. So I laid track in the yard until I ran out of ballast (Mount Airy Starter Grit). When I switched on power to test the new track, a fuse blew in the power supply. After checking to make sure I hadn’t left any metal tools laying across the tracks, I replaced the fuse & tried again, with the same result.
I powered off, removed the loco from the track & put an ohmmeter across the rails. It showed approx. 26 ohms! I rechecked all connections & still had 26 ohms. After disconnecting all power leads, the meter was still reading 26ohms! So just for grins, I put one lead on a rail & the other into the ground - you guessed it, except the reading was approx. 128 ohms.
I’ve checked for ground contact with the rails & none is apparent - does anyone have any suggestions for a cure?

Vance

#2

First thing that comes to mind is a reverse loop. Baring that, maybe a bad turnout?

#3

You have any ballast?
Is it wet?
Or, worse, concreted?

Can you disconnect track?
Go to the first turnout and unplug the track.
Test.
If okay, plug it back in, and go to the next turnout.
Reverse loop, maybe, wet ballast, maybe, bad switch, maybe, screwdriver left across the rails at the far end, maybe.

That 128 ohms…power pack unplugged from the track or not?

#4

Take your turnouts (1 at a time) out of the layout, reconnect the gap where the turnouts were with jumper wires and test again. That is to eliminate the turnouts as a possibility.
As TOC stated, it can even be ballast in some instances.

TOG

#5

I have ballast & it’s a bit damp. No reverse loops, power pack disconnected, & nothing across the rails.

What sort of problem with a turnout do I look for that might be causing my shorting?

#6

Ballast can be a far bigger issue than you think.
However, disconnecting turnouts (this is the third time in this thread it has been recommended), isolated possible miswires or shorting issues (live steam, clockwork and battery users don’t have to worry).

On ballast:

Many years ago a businessman in Tigard, Oregon built an outdoor railroad for a customer.
Calculated the needs of the customer, as far as desired run time, types of locomotives.
On-board radio, with 12V battery power to the track.
BIG deep-cycle battery.
He figured is would run for weeks.
Flat in 20 minutes.
Re-charged, flat in 20 minutes.

Ballast.

And, it really makes little difference if it’s soaking wet or what you may think is dry.
If you have mixed any bonding agent, like Portland Cement, you will have to remove it with a chisel.
If using Aristo track with the screws under the tie bonds, it can short to those screws.
All ballast in a track-powered setup needs to be BELOW the bottom of the rails.

If it’s loose ballast, get a wet/dry shop-vac, and take it all up.

#7

Regarding the ballast… Take a magnet and touch it to the ballast. If you pickup anything, you have iron particles in the rock. This will hasten the shorting problem. It will also cause problems with the locomotives when the magnets in the motors pick up the rocks and put them where you don’t want them.

It is an easy check at the rock store. Just double check when it is delivered, if you don’t pick it up yourself.

Don’t ask how I found out about this one.

madwolf

#8

Did you put an insulated gap in that first passing siding? Or is there a hidden siding somewhere in your track plan?

#9
Steve Featherkile said:
Regarding the ballast... Take a magnet and touch it to the ballast. If you pickup anything, you have iron particles in the rock. This will hasten the shorting problem. It will also cause problems with the locomotives when the magnets in the motors pick up the rocks and put them where you don't want them.

It is an easy check at the rock store. Just double check when it is delivered, if you don’t pick it up yourself.

Don’t ask how I found out about this one.

madwolf


I really disagree with the part about motors picking up ballast particles. The ballast that I used to build most of my railroad came in bags from Home Depot (used for leveling patio blocks) - basically stone dust in a bag. I tested with a magnet long after I had a lot of it down and it stuck to the magnet. I’ve been watching ever since and have never seen any of it stuck to working parts of a loco or inside a motor. I think the distance from the motors to the ballast is just to far from the magnets to attract the ballast. Your mileage may vary.

I’ve since changed over to bulk “stone sand” and “process” from the local quarry outlet but never bothered to test it for iron content because of the above findings.

Also - my Aristo track is buried in this stuff up to the top of the ties. I also have a crossing buried in concrete. I can’t say that there isn’t some current leakage into the ballast and concrete, but it has never been enough to suck down the power supply and keep the trains from running. I don’t run in the rain and my drainage is very good so that may be a factor.

JR