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Frog Polarity issues with Tortoise motors


Halgate1964
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Hello, I'm new to RMWeb.  I am building a DCC railway using Tortoise motors and electrofrog turnouts. The turnouts Open or Throw with each command correctly, however the polarity of the frog changes to the contrary position. Oddly, one turnout of 12 so far installed, is installed under the boards facing a different direction to the other 11 and it is the only one with the polarity in the right place. Any ideas please? I operate a Digitrax system assisted by DS64s if that's any help.

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Hi, I agree with you and have tried that but regardless, the polarity of the frog changes also, so it's always different. I even tried changing the power feeds to the frog (connectors 2 & 3) but of course that just creates a short circuit. These are tortoises that I have had operating perfectly on a previous layout.

 

Cheers,

 

Allan

 

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Each Tortoise has two changeover switches. With the contacts facing you below the motor, 2 and 3 are the inputs and 4 is the output to the frog on one switch. 6 and 7 are the inputs, and 5 the output to the frog on the other. I feel this is not intuitive, and it is easy to think the output is the middle of the three. As Dave says - check your wiring is right? 

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Addiing to Allan Andi & Oldddubbers .

Depending on which way the tortoises are mounted, I.E. before the throw bar or after will determine which connection on the Tortoise (2 or 3) goes to railA

In the drawing if the Tortoise on the LH gives the wrong frog polarity then change the wires from the DCC bus to the Tortiose as shown on the RH side

tortise.png.d7731bb10cf55a676ad002b8f46ffdc5.png

hope this helps 

John

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Have tried switching the input wires over, result was a short circuit. Another common (no pun intended) denominator is that the problem turnouts all had the motor power leads 1 & 8 switched over to coincide with the correct action of the command on the throttle (throw or close). I will concentrate on that being the problem for the time being as I have checked all the wiring (input wires to the frog 2 & 3) and they are correctly wired. Thanks for all the advise guys, I appreciate your thoughts.

 

Allan

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I'm confused as to why swapping the wires to terminals 2 and 3 causes a short.  Assuming @Oldddudders and the diagram provided by @Dagworth are correct, my understanding of the Tortoise is simply that there is a switch that connects terminal 4 to either terminal 2 or terminal 3.  Thus the frog will be connected to one or other stock rail.  Irrespective of whether or not the frog polarity is correct for the direction of the switch blades, it should not cause a short (until a piece of rolling stock runs through the turnout).

 

It's probably a stupid question, but have you definitely inserted isolated rail joiners on both rails at the V, so that the frog is completely isolated and only being powered through the switch on the Tortoise?

 

Are these Electrofrog points being used as supplied by Peco, or have you modified the wiring under the turnout?

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Have you completely isolated the frog, ie not only put insulated rail joiners on both vee-rails, but also cut the wires underneath which link the blade rails to the frog? If you haven't done the latter then power to the frog is still being supplied via the blades. I therefore wonder if there's a possibility that the internal switch in the Tortoise is managing to change the polarity of its feed whilst the blade rail is still in contact with the stock rail, thereby tripping out the DCC command station. This could happen if the springs are still in, meaning there might be a delay before the blades switch. 

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Like others I am somewhat confused as to why a short would occur. Maybe some photos of the points and where the isolated rail joiners are may help us come to the cause of the issue. As a side note some users do modify the tortoise pcb tracks to stop such issues, personally I have not done so, another thought and a shot in the dark is some sort of electrical tracking between the contacts on the pcb

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If the point blades are making contact with the stock rails then creating a short circuit is dead easy, just get the power wires the wrong way round. But obviously the solution is just as easy, swap the power wires around.

 

John P

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A few questions

What scale are the points?

Are you using separate Track bus & accessory busses? If so then the frog wiring should come from the track bus not the accessory bus

If OO peco have you cut the links under the rails from the point blade to the frog?

 

I have a few OO9 points on my OO/HO layout & had problems with the frog shorting

The blades are not isolated from the frog which meant that if the point motor was not aligned properly the the switch in the point motor would change over before the blade moved away from the rail causing a short until the blade moved away  from the rail

6 hours ago, Halgate1964 said:

Another common (no pun intended) denominator is that the problem turnouts all had the motor power leads 1 & 8 switched over to coincide with the correct action of the command on the throttle (throw or close)

I don't see how this can cause a short, they are 2 different circuits

John

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All the turnouts were used perfectly on my previous layout prior to a house move, they are peco electrofrog, they have all been altered and plastic joiners connect the frog rails. All the tortoises were used on my previous layout and were also perfect plus the wiring is the same (I use chocolate boxes so I do not have to unsolder the wires from the tortoise. I dont believe for a minute that the problem is with the tortoise. BTW, its the same with 11 other turnouts. Going out there shortly to go over EVERYTHING again. You guys are scratching your heads and so am I as I fully understand the workings (although not as fully as I thought, obviously). I have not been to the train shed in the garden for 24 hrs due to having to sleep then go to work. Haha, not had much sleep I can tell you.

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1 hour ago, Halgate1964 said:

All the turnouts were used perfectly on my previous layout prior to a house move, they are peco electrofrog, they have all been altered and plastic joiners connect the frog rails. All the tortoises were used on my previous layout and were also perfect plus the wiring is the same (I use chocolate boxes so I do not have to unsolder the wires from the tortoise. I dont believe for a minute that the problem is with the tortoise. BTW, its the same with 11 other turnouts. Going out there shortly to go over EVERYTHING again. You guys are scratching your heads and so am I as I fully understand the workings (although not as fully as I thought, obviously). I have not been to the train shed in the garden for 24 hrs due to having to sleep then go to work. Haha, not had much sleep I can tell you.

I think that you are going to find out, that the same error has been repeated 11 times!

 

Good luck.

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The fact that the one tortoise that is reversed is the only one working does strongly suggest that the wires from the bus to the tortoise switch ‘inputs’ are connected the wrong way round.

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I'd agree that it sounds as though the two switch inputs (terminals 2 and 3) are connected to the wrong stock rails.  When switching these over, did you change the connections on all 11 that don't work at the same time, or was the short a consequence of only swapping the connections on one turnout? 

 

Would it be worthwhile disconnecting the frog wires on all 11 turnouts that don't work and starting again with these one at a time, checking the polarity is correct on the first one you reconnect before moving on to the next one?

 

Alternatively, is it possible to change the orientation of the motors that don't work to be the same as the one that does?  Simply swapping the wires to terminals 2 and 3 should achieve the same thing, but if that doesn't work, then physically changing the orientation of the motor might (although I'm not sure why it should).

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AS a matter of fact David, after finding 11 frogs were wrongly polarized by using the multi meter, I started trying to correct just the one. That could have caused the short circuit. I am away at the moment but will attend to ALL the turnouts on my return. Thankyou.

 

Allan (Halgate 64)

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Just correcting one (as you tried to do), shouldn't really be a problem if the frogs are all correctly isolated, but it's a possibility that the one that you tried swapping the wires on is one where the frog is not properly isolated and somehow being fed from an adjacent turnout / frog.  The approach that I'd take would be to disconnect all of the ones where the polarity of the frog is wrong and then start up connecting the one that is furthest away from the one you were trying to switch the stock rail wires over.  Test that and if it now works correctly, move on until you find one that doesn't work.  Disconnect that once and skip to the next.  Let us know how you get on.

 

 

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