Frog polarity wire broken. Quick question.

[CDRC]

Hi all,
I was moving a point today and caught the frog polarity wire against the edge of layout and pullI gotta the wire out of the point. Is it possible to solder it back?  My soldering skills are somewhat limited and the space is where the wire goes is quite tiny. If not is there an alternative way of attaching wire or wires to the frog?  Having looked under the point I am also unsure where the wire has to be soldered. Or should I just forget it and buy a replacement and chalk it up to experience.
Thanks 

Charles 

Sent from my iPad

[Chrissaf]

Is there an alternative way of attaching wire or wires to the frog?

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Yes there is an alternative easier access location where the frog power wire can be soldered. With reference the image below:

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The two white arrows represent the rails that form the frog. On this image, the factory frog wire is still attached and can be seen towards the left hand side of the white arrow in the 8 o'clock to 2 o'clock orientation. This shows its normal factory fitted location where it has broken off from.

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At the far right hand side of the two white arrows, you can see the double red arrow I have added.

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Now if you remove (snip out with side cutters or a modelling scapel knife) the black plastic webbing under both of the two red arrow heads. Then you will reveal the shiny underside of the two rails forming the frog. You should now be able to solder a wire across these two rails (where the double red arrow is) and extend the wire soldered there to form the new replacement frog wire.

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I am assuming that the horizontal wire links to the right of the double red arrow have been 'broken / removed' on your Electrofrog point to electrically isolate the frog. These links have been broken on the point in this photo, but you have to look very closely to see the breaks. I am not referring to the two longer vertical wire links that are even further to the right (see note below).

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Note: Do not solder your frog wire to either of the two vertical bridging links (if fitted on your point) shown to the far right of the double red arrow. These links are on the main layout track and not the frog.

/media/tinymce_upload/91c5e6a97aba5dec5f2d60576346530c.jpg

Where the original frog wire broke away, check that the cross-over rail link wires are still intact, else part of the frog rails might become power dead rail.

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[CDRC]

Hi Chrissaf

thanks very much for your reply. I think I understand what you are advising. The point has been prepped by cutting the connecting joining wires and I have resolderd new joins in the appropriate places. I attach a pic of the underside of the point which is a little different from the one you have shown. I have positioned a piece of black wire pointing to where I think you say I need to re attached the new polarity wire and that it has to bridge those 2 brass pieces? I'm not really clear on your last sentance though, I re the crossover I have examined the frog with a magnifying glass but I cannot see the wires you mention. 

link wire are intact I /media/tinymce_upload/bfd8794da104785dd7bd45ec9f54153c.jpghave examined the frog with a magnifying glass but I cannot see the wires you mention. Apologies for 

[CDRC]

Hi Chrissaf,

Thanks very much for your reply. I have replied with a photo but both that and the text seem to have disappeared, is that usual? It might just be the server checking the content causing the delay, so I'll wait until the morning before trying again. The text though was as follows 

Charles

 

Hi Chrissaf,

thanks very much for your reply. I think I understand what you are advising. The point has been prepped by cutting the connecting joining wires and I have resolderd new joins in the appropriate places. I attach a pic of the underside of the point which is a little different from the one you have shown. I have positioned a piece of black wire pointing to where I think you say I need to re attached the new polarity wire and that it has to bridge those 2 brass pieces? I'm not really clear on your last sentance though, I re the crossover I have examined the frog with a magnifying glass but I cannot see the wires you mention. 

[Chrissaf]

I have replied with a photo but both that and the text seem to have disappeared, is that usual?

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Yes for those that do not have 'instant image posting rights'. For the majority, posts with images are held back for Admin approval. A Hornby staff member has to approve the image posts (not a ComMod). In the current 'lockdown' situation with Hornby staff working from home. This approval can currently take up to 5 days. You also have to use the official Hornby image uploader tool. The Black & White Hill icon to the left of the Smiley face. This forum does not support 'drag n drop' nor 'cut n paste' for posting images.

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I have examined the frog with a magnifying glass but I cannot see the wires you mention.

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As far as my example image is concerned, these are the 'cross-over' wires I am referring to. They provide the electrical connectivity to electrically join together the four rails that form the frog.

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Here is the same image without my previous overlay added. This makes the wires I am referring to easier to see.

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/media/tinymce_upload/46478f30ab657c3cfd02ed8e3c41631b.jpg

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[CDRC]

Thanks again, 

As said the underneath of my point appears different to yours. It's a new SL-E91 if that helps. I cannot see the two wires you mention though. Hopefully if my photo passes Hornby's scrutiny it will show what I mean. thanks again

Charles

[Chrissaf]

Same point, different manufacturing date .... probably later ... as the thin delicate wires have been replaced with more robust metal strips.

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You shouldn't need to bridge the two contact pads you are pointing at with your wire. They should already be in electrical contact with each other via that bridging pad you can see towards the right. You can see the solder blob where the original frog wire has broken off from (highlighted in green) on the top half of the bridging pad.

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/media/tinymce_upload/7530d96e5a358d1f8b28def6485feed8.jpg

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Since the pad your wire is pointing at has a larger pad area with easier access, then connecting a new frog wire there will be electrically the same. But do use a much thinner wire than the one you are using to point with. The original wire was a fraction of the size.

[CDRC]

Thanks Chrissaf 

that much clearer. I will give it a go

Charles

[CDRC]

Hi Chrissaf,

referring to the above photo. I have at last got around to trying to replace the frog polarity wire. I have prepared the point by following the instructions found on the web for Peco electrofrog points. All well and good so far. I thought I would test the continuity of the frog connections between my black wire and your green square. There is continuity between my wire and the top half of the pad on your green square. There is a very thin brown plastic strip that separates the top half of the pad from the bottom half and bottom half of the pad connects to the upper frog rail. (I believe it is not actually a blob of solder but the thin plastic separator) As you can see the 2 frog rails, the upper and lower, are isolated by a very thin gap. The bottom half of the frog setup being the mirror of the upper half. In light of this do you still recommend I solder the frog polarity wire to the pad opposite my black wire.  Logic would dictate if this is the case the upper frog would be powered but the bottom half wouldn't be. It would seem the polarity wire has to be connected at some point to both upper and lower frog rails and the polarity changed by the Cobalt point motors inner workings. The question is, where. If I connect the polarity wire to the pad where my black wire is because of the very thin plastic strip the upper frog rail wouldn't become live regardless of the change in polarity. (This would also be the same on the bottom half). So somewhere along the line I feel the polarity wire should be connected to both the upper and lower frog rails. So there must be more than one place of contact but again where might this be? I might have this all wrong but would appreciate some advice.......again.

thanks 

Charles

[Chrissaf]

Just use a multimeter set to measure resistance or continuity. At the end of the day you want your wire to be in direct electrical contact between the wire attachment point and the two metal rails that form the isolated electrofrog frog.

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Use your meter to see first of all ... are the two frog rails connected electrically together even without any wire connected.

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If they are connected together, then which pad on the underside also has connectivity with both rails. Then attach your wire to that pad location.

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If the two rails are not electrically bonded together, then which pad on the underside is electrically connected to which rail. Then just make sure that the wire you add is also connected to those pads.

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Simples.....

[CDRC]

The frogs a not connected together. So connecting the polarity wire to the top pad (where my wire is pointing) in isolation does not power any other part of the frog, similarly connection to the bottom pad results in the same outcome. I surmise the frog requires multiple points of contact.  The polarity wire therefore has to be connected to 4 different parts of the frog. Looking at the 2nd photo in this post, the one with the 2 broad arrows pointing down (its the photo you posted) it appears the polarity wire is attached to the frog in those 4 places. As previously said the layout underneath my point is different so it's knowing where along those points I would need to connect the polarity wire that would feed the frog when my point motor changes the direction of the blades on the point is what is puzz me.

thanks

Charles

[CDRC]

Ps.

the connecting wires shown in your photo are missing

[Chrissaf]

My electrofrog points are the same as my original photo. I do not have access to the type of point your photo shows. Without a physical example of your point type to test for myself I cannot help further. If you can't work it out for yourself, you may have to 'bite the bullet' and just purchase a new Electrofrog replacement.

[CDRC]

Thanks

Thanks Chrissaf

It would seem I have little to lose by trying it. If it doesn't work I would have to buy a new one in any case. What is a real bonus is that by writing down the question and thinking about the problem you arrive at a stage where you can understand the problem better. So the mere fact of formulating a query gives insight and understanding.

thanks again 

Charles

[Mac-_-]

Hi CDRC, would it be posible to solder a wire back onto the old spot where the wire broke of?

 

If your not comfortable with soldering, maybe your a member of a club, or have a club sorta close, you could take it there. I'm sure they'd be happy to help.