# Dead Spots on 4x8 oval HO DCC



## robz (Feb 8, 2017)

Now for some reason, I have two dead spots. A few nights ago every thing was fine. Now in two spots both locos, a steam and a diesel both stall. 
The spots are separated, half way round The layout. Same spot every time. I just added three Caboose thows to the Atlas snap turnouts on the near side of the 8'x4' layout. The stalls are on the outside oval. Most of the track is soldered. I did not solder the turnouts. The stalls are few inches from the feeders.
When a locomotive stalls the digitrax flashes and both locos stop.


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## Cycleops (Dec 6, 2014)

It sounds like a short activated by your loco's wheels. I don't have any experience of Atlas turnouts but this video might help you.


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## DonR (Oct 18, 2012)

I agree with Cycleops. If your Digitrax controller flashes
at the point the locos stop, there is some sort of short,
if only momentary.

You might try the same procedure we use to find why
a derail at certain spots.

Run your loco as slow as it will go to the point where
it stops. You should be able to see what is touching
what that could cause a short. There may be a stray
piece of wire, or metal shaving. The weight of the loco
could cause a slight track movement resulting in
an electrical contact.

If that doesn't uncover the culprit you might try
simply pressing with your hand at the spot of
stop. If that also causes the Digitrax to show short,
there has to be some stray contact.

Don


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## traction fan (Oct 5, 2014)

*Shorts at turnouts?*



robz said:


> Now for some reason, I have two dead spots. A few nights ago every thing was fine. Now in two spots both locos, a steam and a diesel both stall.
> The spots are separated, half way round The layout. Same spot every time. I just added three Caboose thows to the Atlas snap turnouts on the near side of the 8'x4' layout. The stalls are on the outside oval. Most of the track is soldered. I did not solder the turnouts. The stalls are few inches from the feeders.
> When a locomotive stalls the digitrax flashes and both locos stop.


robz; 

Are your locos stalling while on top of the turnouts? Have you tried temporarily disconnecting one of the Caboose Industries ground throws? Do your ground throws have built-in electrical contacts, and, if so, are the contacts wired to your turnouts? It's possible that a wheel is shorting between two rails where they almost meet at the frog. This usually happens when the frog's plastic is worn down by long use, or sanded down by misguided modelers. If the rails show at the point of a plastic frog, try painting the top of the frog and see if that helps. 

Regards;

Traction Fan:smilie_daumenpos:


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## Lemonhawk (Sep 24, 2013)

You can make a really nice tester using an alligator clip test wire (cut in two) then use a 1200 ohm resistor in series with a bi-color (usually red-green) two lead LED. It will glow yellow in normal DCC and either red or green on DC. Great for detecting phase problems on DCC track! Use mine a lot.







You can actually the individual red and green LED's so it easy to see which way the track phase is. I mainly used it when testing the frog power to get the phase right.


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## DonR (Oct 18, 2012)

Lemonhawk's tester got me to thinking.

Stop the locos far away from the stop spots and
let them park but with the track 'hot'.

Use your multimeter set to AC and read the
voltage at the track drops. Then slide them along
toward the stop point and see if there is any kind
of reading change. 

Any change means a trouble spot.

If no change do the same but additionally
press on the track as you move to the stop spot.

What happens?

Unless you used the ground throws to change
frogs etc. they should have no effect on the
track. Could you have inadvertently changed
the track drops when you installed the ground throws?

Don


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## Lemonhawk (Sep 24, 2013)

here is an example of a bi-color 2 lead LED
https://www.jameco.com/z/LHG2062-LED-Bi-Color-Green-Red-565nm-697nm-2-Pin_94553.html


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## robz (Feb 8, 2017)

Thank you all for your help. I have isolated the problem three new box cars, one in particular is an issue. When ever that car is being pulled, and that car is passing through two particular turnouts, that's when the problem occurs. I bought three Bachman HO silver series 40ft box cars from M.B. Klein. One car was an issue from the start, kept derailing on the curves, one wheel truck seemed a little loose, but the screw was very tight. I took it off and put a sliver of electrical tape around the post and put the wheel truck back on. It seemed to help, no more derailments. Then the stopping issue became apparent. The other two were okay, but now they are occasionally shorting over the other two mainline turnouts, (no ground throws). I moved them up behind the tender and now they seem okay, only a quick flash on the digi controller. 
The problem car I am not running, going to find out if I can return it.
Thank you all.


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## robz (Feb 8, 2017)

I ordered some last week, should have them by 4/4. I am going to use them inline with a tortise to indicate turnout position on a panel.




Lemonhawk said:


> here is an example of a bi-color 2 lead LED
> https://www.jameco.com/z/LHG2062-LED-Bi-Color-Green-Red-565nm-697nm-2-Pin_94553.html


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## DonR (Oct 18, 2012)

It appears that you may have some out of
gauge wheel sets. Sometimes this happens
on a turnout frog with the thin insulator. One
solution is to put a tiny dab of clear finger nail
polish on the rail EITHER side (but not both)
of the insulator. This will prevent the metal
wheels from shorting. Others have used a fine
file on ONE rail.


Don


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## robz (Feb 8, 2017)

13 volts consistent.





DonR said:


> Lemonhawk's tester got me to thinking.
> 
> Stop the locos far away from the stop spots and
> let them park but with the track 'hot'.
> ...


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## jlc41 (Feb 16, 2016)

robz, by chance have you check the wheels for proper gauge???


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## robz (Feb 8, 2017)

"It's possible that a wheel is shorting between two rails where they almost meet at the frog. "
This what I think is happening on the new box car.

The ground throws are not wired.
The Atlas snap turnouts are about a month old. I do not see any metal at the plastic frog.

Are your locos stalling while on top of the turnouts?
For this issue they are not, occasionally they do stall when backing through for switching. Its annoying but livable.

I am running very slowly the loco with two of the new cars and have not had a stop for about 45 minutes.




traction fan said:


> robz;
> 
> Are your locos stalling while on top of the turnouts? Have you tried temporarily disconnecting one of the Caboose Industries ground throws? Do your ground throws have built-in electrical contacts, and, if so, are the contacts wired to your turnouts? It's possible that a wheel is shorting between two rails where they almost meet at the frog. This usually happens when the frog's plastic is worn down by long use, or sanded down by misguided modelers. If the rails show at the point of a plastic frog, try painting the top of the frog and see if that helps.
> 
> ...


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## robz (Feb 8, 2017)

What is a phase problem? Would that be a bad controller?




Lemonhawk said:


> You can make a really nice tester using an alligator clip test wire (cut in two) then use a 1200 ohm resistor in series with a bi-color (usually red-green) two lead LED. It will glow yellow in normal DCC and either red or green on DC. Great for detecting phase problems on DCC track! Use mine a lot.
> View attachment 295417
> 
> You can actually the individual red and green LED's so it easy to see which way the track phase is. I mainly used it when testing the frog power to get the phase right.


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## robz (Feb 8, 2017)

I do have a gauge, and checked the wheels when the derailing problem was an issue. Not sure if I am doing it right, using the notches marked wheels, put the flanges in the slots and they fit squarely.



jlc41 said:


> robz, by chance have you check the wheels for proper gauge???


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## Lemonhawk (Sep 24, 2013)

We typically talk about connecting the red output to the right rail and the black to the left rail, but if you have a reverse loop or a switched frog sometimes across an insulated joint the red side meets the black side and when the loc crossed the insulated gap it shorts. Since DCC is an A/C waveform they are out of phase. A reverser quickly detects this phase difference and switches the power to the rails to get it in phase.


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## robz (Feb 8, 2017)

Can I switch out the metal wheels on the problem box car with plastic? Would that "fix" the car?


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## MtRR75 (Nov 27, 2013)

robz said:


> Can I switch out the metal wheels on the problem box car with plastic? Would that "fix" the car?


That should definitely fix the problem -- if it is being caused by the metal wheels momentarily touching BOTH rails at the frog. If the problem persists, then we start over figuring it out.

What kind of turnouts are you using? There are some possible modifications to the turnouts that should eliminate the problem and allow you to keep your metal wheels.


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## jlc41 (Feb 16, 2016)

robz said:


> I do have a gauge, and checked the wheels when the derailing problem was an issue. Not sure if I am doing it right, using the notches marked wheels, put the flanges in the slots and they fit squarely.


That would be correct.


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## CTValleyRR (Jul 26, 2014)

robz said:


> Can I switch out the metal wheels on the problem box car with plastic? Would that "fix" the car?


I would not advocate this as a permanent fix. Most of us would advise you to convert to metal wheels because they generally perform better all around.

However, this might be an excellent way to identify whether it is in fact the wheels that are shorting, then you can figure out a fix for it.


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## robz (Feb 8, 2017)

I am using Atlas snap switches. (I know, for now on I will only get Peco). I put some plastic wheels from a car I bought used and now no problems.




MtRR75 said:


> That should definitely fix the problem -- if it is being caused by the metal wheels momentarily touching BOTH rails at the frog. If the problem persists, then we start over figuring it out.
> 
> What kind of turnouts are you using? There are some possible modifications to the turnouts that should eliminate the problem and allow you to keep your metal wheels.


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## jlc41 (Feb 16, 2016)

Glad you got that sorted out. good job.


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## traction fan (Oct 5, 2014)

*Shorts at turnouts?*



robz said:


> I am using Atlas snap switches. (I know, for now on I will only get Peco). I put some plastic wheels from a car I bought used and now no problems.


robz;

First of all it's good to hear you are no longer having the problem. Since that happened by replacing the metal wheels with plastic ones; then you must have had some sort of wheel-related problem. It would be nice to find out what actually caused the stall. As CTValley said, metal wheels are better, (more free rolling, add some weight where it does the most good, at the bottom, and are slightly less likely to pick up dirt) than plastic. Of course you could simply leave the plastic wheels on and call it a day, but that won't identify the source of the problem. Your railroad, your decision. I'd like for you to be able to get the benefit of metal wheels, if you wish to. If you meter across those metal wheels you took off, do any show a short circuit, aka. zero resistance? They should each read open, that is very high resistance. If the wheels themselves are not shorted, it may be some interaction between the wheels and the track that caused the problem. The most likely place for this to happen is the one that's been mentioned several times, at the frog of a turnout. In your diagram though, the area where you had the short does not appear to be on a turnout, but before your train gets to the turnout. Very puzzling!

Good luck;

Traction Fan:smilie_daumenpos:


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## MtRR75 (Nov 27, 2013)

traction fan said:


> robz;
> If the wheels themselves are not shorted, it may be some interaction between the wheels and the track that caused the problem. The most likely place for this to happen is the one that's been mentioned several times, at the frog of a turnout. In your diagram though, the area where you had the short does not appear to be on a turnout, but before your train gets to the turnout. Very puzzling!


I think that Robz marked where his loco stalled in his diagram, then later discovered that one of the cars was causing the short at the turnout. Note that at the two problem locations are the same distance past a turnout (given his counterclockwise train movement).


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## MtRR75 (Nov 27, 2013)

robz said:


> I am using Atlas snap switches. (I know, for now on I will only get Peco). I put some plastic wheels from a car I bought used and now no problems.


I inherited a layout full of Atlas Snap Switches and have spent much time troubleshooting them.

Atlas snap switches have some design shortcomings. But the bigger problem is a lack of consistency in their manufacturing. Look at the end of the frog where the two tracks diverge from each other. You will see two rails that get very close to each other. Those two rails are of opposite polarity, because one is a "left" rail and the other is a "right" rail (Right and left is relative to the direction of train travel.)

If you look at all of your Snap Switches, you will probably find that on some Snap Switches those two rails are closer to each other than on other Snap Switches (inconsistent manufacturing). If the rails are too close, metal wheels can contact both rails at the same time, shorting your power supply.

Take your offending car and hand-roll it slowly across the offending Snap Switch. I'll bet that you will find that the wheel touches both rails.

How to fix this? I take a tiny, triangular file and gently file the OUTSIDE edges of both rails so as to make the rails thinner (NOT shorter), and farther apart. By outside edge, I mean the outside of the TRACK, not the outside of the frog. Another way to describe it is to file the sides of the rails where the wheel flanges do NOT run.

I have read that others will use a Dremel tool with a thin cutting disc to separate these two rails farther, but I do not own a Dremel, and I like going slower, by hand. It is too easy to cut too fast and too much with power tools.

You can test whether this solution will help your trains run better, before you file the rails, by putting a dab of clear nail polish on the tops of the offending rails. If your trains run fine, then that is where the problem was. But the nail polish is only a temporary fix. It will wear off quickly.

I suggest that you address the track issue, even though changing to plastic wheels solved the problem. Your locos have metal wheels (for power pick-up) and can sometimes stall at the frog for the same reason -- especially if you have steamers.

Also, the reason that changing the order of cars in your consist reduced the problem is because there is always a little bit of slop in how wheels fit track. The amount of drag on a given car will vary depending on how many cars are behind it. The differences in drag will cause wheels to shift a little left or right as they go around curves. So the bottom line here is that moving cars around is not a permanent fix.


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## robz (Feb 8, 2017)

Is this the trouble spot? (red circle)


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## Tom17 (Jan 14, 2016)

No, it is where the line from the word frog and the v shape meet.
The drawing you posted shows the frog is insulated, which Atlas snap switch is not.
Th frogs rails come to a point near the frog is where you have to look at.

Look at this video and go to the 7:36 mark or could use a file as MtRR75 posted or use nail polish.


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## robz (Feb 8, 2017)

Great video, I think that will help a lot!



Tom17 said:


> ......Look at this video and go to the 7:36 mark or could use a file as MtRR75 posted or use nail polish. https://www.youtube.com/watch?v=fC3rm_HSu8c&list=PLrnIcagrY_uskGlQhR2g9yrWaJfweROVJ


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