2015_10_13 Monday was spent on wiring, and wondering why my Digitrax DCC system appeared to be slowly losing its ability to control trains, or rather why I was losing control of said trains.
I had four engines on the tracks. The new 42109 as well as P11 and Y 131 . They were there for testing. Its a huge railway and takes a long time to run around. So engines were placed around the room, and called up as required.
Each modification to wiring was tested, that is until it all came to a stop!
The track tesing meter showed a DCC value of 16v with a strong signal, everywhere. However not one engine would move.
I changed out command stations and finally opened up decoder pro and then checked all engines. They were ok, but all (except Y131) had the address 3556 ??
I dont own 3556? Y131 was addressed 3131 however now it was 131 (the address it had when I bought it). It has been 3131 for a long time. Decoder pro recorded it as 3131. So I know not what happened here.
All engines were saved in their original configurations and now answer to their original address'
Whilst trying to get something to move, I rewired several sections and cleaned all track. I found an interesting dead section though. At the top of the helix I have a short section insulated from the top level district and the bottom Level District. The Helix is a third district. My DCC bus is divided into three matching sections. The droppers were not connected to this short section separating the Top level from the Helix. So I wired it back in to the Helix, long droppers connected I tested for DCC and found nothing. I got a multi meter adjusted it to AC and got 13.9 v on the top level. 14.4 v on the helix and 4.7 v on the short joining section. Swapped the leads and got a pulsing 2v or so. conected top level black rail to short section red rail and got 13.9 v switched rails and got 4.7 v ??
Tried a train... it arrived from top level and set of the circuit breakers when I entered the short section.
I reversed the red and black wires on this short section. the train still shorted out, however now it shorted as it entered the helix, and if I pushed it clear of the insulators it would restart and continue on down the helix, passing all the way down and enter the bottom district. It would reclimb the helix and short out again as it tried to enter the short section prior to the top district. push it and it continued on into the section. What is it doing? It acts like a reverse loop??
However it is not the Black bus line remains connected to the same rail that is it is the outside rail on the bottom level and because of a change in direction it is the inside rail on the top level, just as it should be. Absolutely no reversing loop here.
that short insulated section between top level and helix was actually a braking section, to prevent a train entering the helix, until the helix was clear.
Not sure why I did it, however I decided to temporarily connect a dual frog juicer with paired frogs to the short section. I ran the red and black feed wires into the DCC connector and the red and black track wires into the out put. I got a red and green light up on it. Run a train through from either direction and the red and green leds swap colours. So where the hell is the reverse loop??
No matter it works. Not only that but everything works, voltage has gone up to 16.1 volts and the DCC controllers work just fine, once again...... A WIN :D
Having DCC address changing unintentionally got me thinking about radio interference. When laying my bus I did not know about radio interference and had no idea that 30 feet of DCC bus wiring needed to be twisted loosely to minimize this interference. However having not done that, I find their is a thing called a snubber I can link between the bus wires to help improve things. However their is a consequence to using snubbers. You cannot use current detection for your signalling, because the snubbers allow a current to flow which trips the detection with false occupations.
And so if you are building a new layout you should learn about this and a fine article can be found here DCC Snubbers and lots more
I am going to use the NCE snubbers which I found in the DCC manual thanks to the good folk here on DCC Downunder
I also tried to get the android WiFi controllers working, but gave up on that. two out of three is not so bad, try wifi another day :)