Curious new DCC wiring problem

[yelrow]

Hi, Have Frateschi turntable, Chipped with decoder, as no 22. That continues to work, perfectly. However, today, re introduced it into the layout, with point off outer loop. When loco commences on TT. there is a short, and Error on Elite. So, used a 12 volt tester, with a strange outcome. Bulb lights up on tester on same rail, throughout layout, but when connecting to Just TT, and loco sheds that connect to it, from other end, all these are reversed. EG. bulb lights up on opposite rail. Hence the short. The only thing i have changed, is the path from TT, to layout. It still enters the outer loop, but from a different part of the layout. I have 3 loco sheds, coming off 3 exits from TT, which have their own feeds, to enable them to depart from sheds, and as with . TT, they are lighting up on opposite rail. What have i done wrong. New point has wires soldered across, same as all the others, and BUS, works fine. Help. thanks. john

[Brian]

May be worth reversing the two TT rail feed wires?

[yelrow]

Hi, FB, thanks for that. Cant fathom out, why it should suddenly have mind of its own. Will take another look tomorrow.

[Brian]

It could be???? due to moving the feeds and the split ring of the TT connection no longer being in the correct place??? Hence my suggestion of reversing the TT rail connections

[yelrow]

Yup, i thought about that. New layout feed, previously, just a siding, which worked fine. I will run it 360 degrees tomorrow, and find out where, if, polarity changes. As an aside, would it work to wire Tam valley auto reverser in. Would that eliminate prob. If so, what do i need to set up on the reverser. thanks. john

[Brian]

Hammer to crack nut seems the answer re a Reverser. John!
Try checking the TT to see if it has a split ring and where any new feed is now entering the TT. This IMO seems to be the problem especially if it worked correctly before altering feeds.

[yelrow]

Was only cos I had a reverser in a drawer, accept its ott. Will report back. Thanks john.

[RAF96]

I was going to suggest the TT was 180 out or the wrong road had been used as the in-road as presumably this sets the TT bed basic polarity.

If wrong in-road was used and the bed is moved off line then could this give the 180 degree out symptom as at some point the bed has to swap polarity via split slip rings if that is the system used.

[yelrow]

Hi Rob, TT had been disconnected for some time, and i laid track to it, connecting it to a different road. Will either try to line up with original point of entry, or may be, rotate TT, so new track lines up with road no 1. You do these things, thinking what a good idea, then repent at leisure. john

[yelrow]

Followed FB,s advice and reversed supply, with good result. As track is now on correct entry track, and TT, was still reversed, cannot understand why polarity decided to reverse. All serene now, but would like mystery explained.