Tortoise Machine Switches


D&J RailRoad

D&J RailRoad

Professor of HO
I have Tortoise machines all over my layout and on the modules. I use the switch features on the Tortoise for frog power and dwarf signals.
The problem I'm having is momentary shorting of track power when I throw some of the turnouts. Not all of them do it.
I have checked the polarity to the frog and it's correct, closed or thrown. The power for the frog is taken from the track buss wire. Because I use 3/4" plywood on the layout and 5/8" plywood on the module, the provided throw wire isn't stiff enough so I've replaced them with #16 piano wire.
The turnouts throw all the way and the points are held firm against the stock rail on each side.
It's just a momentary short that stops all trains during the switch transition. They all resume movement right away after the turnout finishes it's movement. The Tortoise does not stop moving during the short as they are powered by DS64s with PS14 power supplies. The locos aren't on the turnout when it's thrown. Sometimes a couple feet away other times 20 feet away or more.
 
Thanks for making my bald spot bigger. Have you tried disconnecting just the frog or signal wires on the problematic turnouts? Might be a way to isolate the problem.
 
Disconnecting the frog powering wires would leave the frogs unpowered and a long dead rail on the #10 turnouts.
I think the problem may be the brass wings on the points of the turnout. They may be making contact before the tortoise moves out of the first contact position.
I'll clip the frog lead on one and see if the problem stays or goes.
 
That actually was what I was thinking. Could the points be moving too much before the internal switching takes place. Just didn't want to sound like a dummy if I'm thinking about this wrong.
 
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But the frog should be isolated and point contact shouldn't matter unless wheels are rolling over it. Bigger bald spot.
 
The points make contact with the stock rail in each position. The Tortoise machine also provides the electrical path for the frog. The tortoise machine is a more reliable path though.
 
Yep, I can slip a knife point between them down to the plastic tie bed.
Remember now, I said the short is momentary, while the Tortoise is moving the points.. If there was contact through the rail the short would persist.
 
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Based on how you framed your question, I suspect your problem is not in the turnout, but in the internals of the Tortoise.

I assume you have this problem on just a few turnouts (you said "not all of them do it"). I assume further that it is always the same turnouts that cause the problem. I can think of two possibilities:

FIRST, you may have a few Tortoise machines that are causing a momentary internal short when they are moving. To diagnose this, simply swap Tortoises from a trouble-free turnout to a problematic turnout. If the problem follows the Tortoise, there is definitely an internal issue and you need to replace the machine. If removing and reinstalling the machine is difficult, you could try replacing the machine with a brand-new Tortoise, but that would not be definitive (the new Tortoise might have the same issue.) If you don't want to mess with changing the Tortoise, skip down to "Brute Force and Ignorance."

SECOND, if you are using edge connectors on your Tortoises, be sure the contacts are lining up exactly right. I have had issues with edge connectors bridging two contacts on the Tortoise, creating a short. If this is your problem, diagnosing and correcting will be more difficult.

Now I come to the Brute Force and Ignorance solution (named by my professor in Numerical methods, who was fond of saying "there is no problem that cannot be solved by brute force and ignorance"): disconnect the frog from the Tortoise and power the frog through a Tam Valley Frog Juicer. These babies are simple to install and they are bullet-proof. A Frog Juicer will cost you $14 - about the same as a new Tortoise. If you need more than 4 frog juicers, buy the Hex Frog Juicer, which will power six different frogs.

Good luck.
 
I'm going to install some 12v automotive brake light bulbs in series with the frog feed. Several people have suggested this to stop the shorting.
Once again, the shorting action is only momentary, i.e. a fraction of a second.
 
D&J RailRoad said:
I'm going to install some 12v automotive brake light bulbs in series with the frog feed. Several people have suggested this to stop the shorting.
Once again, the shorting action is only momentary, i.e. a fraction of a second.
Click to expand...
Yeah, the fact that the short lasts just a fraction of a second makes me think the issue is not with the edge connector, but internal to the Tortoise. I have panel indicator lights wired to the Tortoise contacts, and one light ALWAYS goes out a fraction of a second before the other light goes on; but I can imagine an internal fault (or, more properly, poor tolerance) that would cause both contacts to be energized at the same time.

Here's another "brute force" solution for you: install Keep Alives on all your locomotives. The Keep Alives will keep everything running while the DCC system recovers from the short. Doesn't exactly feel like a "best practice" though, does it?

I'll be interested to hear if the brake light does the trick. What is the theory?
 
Also, don't forget a 12V light bulb will consume enough voltage that the DCC signal disappears... You might lose power to frog anyway (although it might keep the rest of the layout running.)
 
I'll reiterate the problem.
It is a momentary short, a "fraction" of a second while the Tortoise moves the points.
 
I understand that when you operate the problematic turnouts, the DCC system shuts down for less than one second, just as it would if there were a short across the rails. Then it properly powers back up, presumably because the short has corrected itself.

Obviously, something is causing a momentary short as the turnout is moving. The only things moving are the points and the Tortoise itself. You have already discussed troubleshooting the turnout and the points, which is why I think you need to look at the Tortoise. The auxiliary contacts are supposed to close at the very end of travel, but I think it may be possible that for a very short time during travel, both sets of contacts are closed, creating a short between the rail power buses.

How many turnouts have Tortoises? How many turnouts exhibit the momentary short? Is it always the same turnouts that have the issue? Does every one cause the short every time? Does the short happen regardless of turnout direction? i.e. straight to diverging and diverging to straight?
 
All my turnouts have tortoise machines.
Only a few of them exhibit the shorting problem. Shorting occures when throwing either direction.
 
If it's always the same few turnouts causing the shorts, I still think your best best is an internal short in the Tortoise. You can confirm my diagnosis in either of two ways:

ONE: Swap the Tortoise from a malfunctioning turnout with the Tortoise from a trouble-free turnout. If I'm right, the malfunctioning turnout will now work fine, and the formerly good turnout will now malfunction. (On the off chance that both now work fine, or both now malfunction, you need to consider the edge connectors again.

TWO: Go to Yankee Dabbler ad buy a Tam Valley Frog Juicer. It'll cost $13.50 plus shipping. Disconnect the raill bus wires from the Tortoise and hook them up to the Frog Juicer. Disconnect the frog power lead from the Tortoise and connect it to the Frog Juicer. If my diagnosis is correct, the turnout will now function fine.

If the malfunctioning turnout continues to malfunction even after ONE or TWO above, then you must have a physical short in the rails.
 
Opened up a Tortoise Machine to see how the contacts are layed out.
In the picture below you can see the circuit paths. The black arm to the right of the circuit board contains the brass wipers. You can see on the circuit board where the wipers have been wiping back and forth between the circuit tracings. Each wipe is actually two prongs side by side. I can see that if one of the prongs gets bent it could possibly make contact with the opposing trace before the other wipe prong breaks contact with the first.
The Tortoise in the picture is not one that was mounted on my layout or modules. It's just an old one from another layout from decades ago that's been in the spare parts box.

To Wizz-bang. When you conducted your recommended course of action on your Tortoise machines, were you able to repair the faulty Tortoise?

20211117_082135.jpg
 
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