Thursday 24 July 2014

Turnout problem continues

Its all about resistance or is it capacitance

Per my earlier post, Im still having issues with the hand built turnouts and block detection.

I also posted a question on the RailWire Forum to seek help there also.
http://www.therailwire.net/forum/index.php?topic=33418.0

I changed the detection threashold on the BDL's to high / 10K with little change to the issue.

I then did some testing and I think I have found the problem.. But the solution eludes me for the moment.

I tested 4 newly cut copper ties and found the gaps to be all open circuit.
I then just placed the tie in the Fast Tracks jig as I would normally do and added a dab of flux..

BINGO.. The tie now is no longer open circuit and now has resistance across the gap. I think the flux is wiking into the fiberglass tie and is causing it to conduct.. All be it with a high resistance.

Here is the flux I am using..

Here is an example of a meter reading.. It is important to note that each join gives a different reading.

I have not tried to clean the tie as yet.. I have just applied the flux and let it dry..

Now to find the bext way to clean the flux off and then find a way to apply it to the built turnouts..

Thanks for checking in.

Posted by at
Labels:

2 comments:

  1. Ron McF24 July 2014 at 17:17

    Can't help thinkin' if all else fails, read the instructions..

    "(4) Remove flux residue with water." LOL

    Jaycar sells a product called Circuit Board Cleaner (http://www.jaycar.com.au/productView.asp?ID=NA1008). I notice that in their product description, Jaycar says "many circuit problems occur when flux and other contaminents (even finger prints) remain on the PCB causing 'leakage' between tracks".

    I doubt that they meant RAILROAD "tracks" but the message is the same. I have a can of this and it seems to work a treat.

    Regards,
    Ron

    ReplyDelete
  2. Rod Warren24 July 2014 at 19:23

    Brendan
    When I modified all 108 of turnouts back in 2003 / 4 I did not use a liquid flux. I used resin cored solder and never had an issue such as you. Then I used Carrs Green label flux available from Brunell and no spray.
    On those that I have fail during ops sessions I use flux from Brunell models, sprayed with the same stuff Ron is referring to and it does not seem to have caused any issues and you know how many I have done.
    Move away from that flux and purchase the best rosin cored solder you can.
    Rod.

    ReplyDelete

Subscribe to: Post Comments (Atom)