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Help desperately needed to cure a short!


Andy 17
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Hi everyone, I really need some help to cure a problem with a short. It's all to do with a passing loop on my DCC 009 layout that I'm building. I am using Peco electrofrog points.

 

I have a passing loop as per the drawing. When I set the points for a loco to go straight on, I get a short. If I change the right hand point towards the loop, the short goes away. Changing the left hand point makes no difference to the short.

 

The red and black dots are track feeds, there are two IRJs on each point where indicated. The two small circles indicate where the wire from the SEEP PM1 point motor attaches to the frog. The point motors have a polarity switch and I'm using on/off/on momentary switches and a Gaugemaster CDU to change the points. I tested both of the points and they changed with no problem.

 

The point motors are wired up as per the diagram and connected to the track at the toe end of each point but the blue, white and yellow wires are not yet connected to the switches or the CDU.

 

Any help would be appreciated as I can't figure out what's going on, and I will have an identical passing loop on the other side of the layout and can anticipate problems with that one too.

 

Best Wishes

 

Andy

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2B4B5524-9F03-4717-AAF8-7CC43EDCA110_1_201_a.jpeg

Edited by Andy 17
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It happens, troubleshooting can be maddening, you check stuff you did yourself and dont notice the simple error.

 

Check that you havnt reversed a power feed to the right hand point. Also, and Im not on very solid ground here, check that the polarity change at the frog is working in the right direction when the SEEP operates. So after double checking the power feeds, disconnect the frog wires and check again. Disconnect unfortunately may mean cutting cables.

 

There are folk who will tell you that SEEPs arent that great for polarity changing anyway.

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29 minutes ago, Andy 17 said:

I have a passing loop as per the drawing. When I set the points for a loco to go straight on, I get a short. If I change the right hand point towards the loop, the short goes away. Changing the left hand point makes no difference to the short.

Andy,

 

Did you remember to remove the 2 little wires on the underside of the turnout that connect the frog to the 2 inside intermediate rails?

 

Ian

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4 minutes ago, ISW said:

Andy,

 

Did you remember to remove the 2 little wires on the underside of the turnout that connect the frog to the 2 inside intermediate rails?

 

Ian

Hi Ian,

 

I asked the same question about the 009 points to the Peco Technical people, this is their reply;

 

Thank you for your email.

We can confirm that no wires or rails should be cut on these turnouts, and only the insulated rail joiners are required on the frog rails.

 

Kind regards

A Beard

PECO Technical Advice Bureau

 

For that reason, I have not cut them, I can only just about see them!

 

Best Wishes

 

Andy

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22 minutes ago, RobinofLoxley said:

It happens, troubleshooting can be maddening, you check stuff you did yourself and dont notice the simple error.

 

Check that you havnt reversed a power feed to the right hand point. Also, and Im not on very solid ground here, check that the polarity change at the frog is working in the right direction when the SEEP operates. So after double checking the power feeds, disconnect the frog wires and check again. Disconnect unfortunately may mean cutting cables.

 

There are folk who will tell you that SEEPs arent that great for polarity changing anyway.

I've already checked the power feeds, they are correct. I'll try a new wire for the frog polarity next.

 

Best Wishes

 

Andy

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8 minutes ago, Andy 17 said:

For that reason, I have not cut them, I can only just about see them!

Andy,

 

Going back to your diagram, and in particular the turnout on the left. With the turnout set to 'normal' (ie: straight) what happens when you test for continuity between the frog feed and the BLUE dot (should be a short) and then to the RED dot (should not be a short, but I think it might be)?

 

Then try the same test on the turnout at the right of your diagram.

 

Ian

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Andy,

 

Just to add, if you are using the switchable frog function (your green wire), then you are supposed to cut the 2 little jumper wires. This is in accordance with the instructions on the 'back of the packet':

2021-01-24_144717.jpg.2ba409b732de1067c52e854e9d6a4bbc.jpg

 

I hope this helps.

Ian

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Might be worth putting a DC voltage through the bus and using a multimeter to verify polarity and making sure their is no continuity through the insulated joins.

 

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There are so many different things going on here, and a fair bit of partial (and I think likely to be misleading information). 

 

Firstly, design of Peco 009 (and N) Electrofrog turnouts:    They are DIFFERENT to the OO ones, so don't follow OO instructions with them!   
As supplied, and as intended to be used by Peco, the N/009 frog is switched by the blades of the turnout touching the running rails.   Peco do not expect an external frog switch to be fitted to them.    So, if fitting an external switch (eg. on a turnout motor), you've got to be ready for "issues"...  

 

 

If using DCC the track is powered at all times, so shorts can occur as turnouts are thrown.  Different to DC, when there is often no power on the track.   

If one then uses an external switch (eg. on a turnout motor), then there are TWO switches to the frog.   That means there is a possibility of the switches not moving exactly together (momentary short as one has moved, but not the other), or one of them not moving at all or not moving far enough to change contact (short in one direction).    Add in the fairly small throw of a N or 009 turnout, and the possibility of a short due to the switch on the motor gets quite high.  

 

So, where to start looking ?  At the motor, and its alignment with the turnout.  Can the motor be moved a little in relation to the tie-bar, and does that alter the short ?   I'm suspecting the motor is not moving enough in one direction to change it's contact.  

 

 

How to fix the problem so it doesn't occur again ?  I can think of these options :  
a)  use turnouts the way Peco intended and don't use external frog switches on motors.  Provided you don't get paint/ballast/gunge on the contact tab on the blade, the turnout will operate reliably the way Peco designed it.   

b)  modify the turnouts to fully separate the frog from the blades.  To do this requires cutting two rails (where the blade rails get near to the frog, thus splitting the frog from the blades), and installing two jumper wires (to ensure the blades are powered at all times).   This is fairly drastic work.   (The new N "Unifrog" designs get round this problem). 

c)  use an electronic frog switching device, such as a Frog Juicer (several makers offer these types of device).  This still has a minor problem (potential for out-of-spec wheel shorting at the open blade), but it fixes the problem of switch synchronisation.  As the turnout moves and makes contact at the blades, a short occurs and the electronics switch the frog power the other way.  If the blade doesn't make good electrical contact, then a loco moving onto the turnout will trigger the short and the electronics responds and switches the frog power.   

d) device a switching setup which is reliably synchronised with blade movement.  I can think how to do it with two microswitches, carefully aligned with tie-bar movement, but its a lot of faff to setup.  

e) make your own turnouts which are designed for a frog to be switched externally 

 

- Nigel

 

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  • 2 weeks later...

I've finally sorted the problem of the short. It seems that the wire to the frog from the SEEP PM1 point motor was causing the problem as it's not needed on the Peco Electrofrog 009 points.  I've disconnected the wire and everything is now working as it should.

 

Many thanks to everyone who offered me advice.

 

Best Wishes

 

Andy

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