Peco N gauge double slip wiring problem

[rynd2it]

I have the double slip operated by two servos using MERG controls and micro switches on the servo mount to change polarity.

 

I wired it so the right hand blades moved and switched the right hand frog and the left hand blades  switched the left side frog. Despite carefully checking that the polarity was correct for the blade setting trying to turn from say A to C or B to D would not work. If the blades we set for that routes, then the frog was the wrong polarity and it shorted out. Going straight across (A to D, B to C) worked fine.

I then discovered that Peco specifies the blades at the left should control the polarity of the right hand frog and v.v. I changed to that but I still get a wrong polarity when trying to turn rather than going straight across.

 

Layout is wired for DCC (everything live) but I was testing using DC (handles shorts better) . I'm at a loss to understand what is going on so would appreciate some guidance

 

[jpendle]

Hi,

 

First the slip must be completely isolated from the rest of the layout.

 

Second, Peco are correct, left microswitch/servo controls right frog and vice versa.

 

There are 4 dropper wires, The two on the outer rails should be wired to the DCC bus maintaining polarity with adjacent trackwork.

 

Regards,

 

John P

[rynd2it]

After another look at the Peco diagram, it shows IRJs installed on all slip approach rails, and the two supplied droppers connected to the track feeds (DCC bus). While I am willing to follow the diagram, it seems strange to isolate the stock rails then connect it directly to what it would be connected without the IRJs.

I'll have to experiment with this, it does seem counter intuitive.

 

Thanks for the help, I'll report back in due course

 

 

[Nigelcliffe]

The isolation of the stock rails is the starting position, because in many track formations there will be other turnouts just downstream from the slip which will likely have polarities changing at crossings (frogs).   

 

When you get it all straight and working, if you then find that an IRJ is doing nothing because the rails each side are always the same polarity, then that IRJ isn't needed.      But, start from an isolated slip and get that working first.  

 

Double slips are like two turnouts which have been slid over each other.  If you pull it apart (mentally) so the tie bars lie beside each other, then the control of crossings (frogs) from each tie-bar becomes more obvious. 

 

 

[rynd2it]

OK, first off it's now working ok after some studying and experimenting. There is no point (sorry) is isolating the stock rails as they are connected to the bus, any adjacent frog V-rails will have their own IRJs.

My big mistake was not following the advice to use switch A to change the polarity on Frog B. Having corrected that and run tests it was obvious that the polarity settings were reversed, simple to correct and now is all running as required.

 

Thanks for all the help and input, very much appreciated