I recently purchased a DCC system and started the layout conversion from DC block control. The operations are fine with the DC blocks. I thought I would convert the front-most track of my classification yard to a switchable programming track. I isolated what was the common rail and used the existing double pole block switch. But, I could not read the loco addresses correctly. At first I thought the wire run from the system through the block switch to the track was too long perhaps as the system is several feet from the control panel.
To make sure I could still read the addresses, I hooked up a couple of test leads with alligator clips to the command station and connected the clips to a piece of track. This was successful (and is how I programmed the addresses originally).
So then I attached the test lead clips to the programming track on the layout with the block switch in the "off" position. No address read! This track is completely isolated but for some reason I can't program on it, but I can program on a 2 foot piece of loose track.
In researching this I did see some forum entries that recommend the on-layout programming track should be about 1 1/2 times the length of the longest locomotive. But I just made my prog track the length of the yard track - about 8 feet.
Can track length affect the programming track? The locomotive was right next to the alligator clips. I polished up the track also to make sure that wasn't the problem. Anyone have thoughts on this?
George V.
The length isn't the problem.
So, make 100% sure that the track is isolated. I know, you did that, but do it again. Then make sure that you have a good connection from the command station to the rails. Also, make sure you have clean wheels.
Jeff But it's a dry heat!
Would a resistor across the rails help in this particular case?
-Crandell
selector Would a resistor across the rails help in this particular case?
What worked on the stand-alone track should work on the programming track.... assuming the same loco, etc. So, in my opinion, I would not add more variables. More info on the setup would be useful.
Doh! Found the problem... I dug out ye digital VOM again. The track section itself still had no leakage across the rails. Then for some reason I tested resistance between the programming track and other rails, including from the common rail on another track to the former common rail of the programming track section..... Whaddya know, there's a number on that there meter.
Normally my track feeders stick out like some sort of growth on the rails. But not the second common rail feeder that went to this track section .....
To answer the comments about need for an on layout programming track - while you can program everything on the main, I just don't have a space for a physically separate track. Switching out one of the yard tracks seemed like a relatively simple solution (at the time!) I did read about wiring dead sections on either side of the programming track. That was going to be the next step.
You got lucky. Always test with a meter before going live. Many times shorting track power to the programming outputs will fry the command station's programming output. That's why David recommended a separate programming track. Mine is on the workbench.
I don't see anything wrong with an on-layout programming track, provided it's properly isolated. I plan to have one in a loco service facility planned in my yard. The loco service facility becomes an actual function!
I agree, but one must have a good idea of the risks involved with an on-layout programming track, particularly if that section comprises part of the layout's tracks, as I did in my case. Gaps are necessary, and an electrical switch to isolate/cut out the power to the tracks around so that no DCC signals are received by other decoders at the same time. You only want the programming signals going to the one length of track. It is just that a metal wheel inadvertently bridging the two "districts" that is part of the electrical pickup base for the engine or passenger car with lighting will act just like it was a soldered jumper between your two districts, and your other locos will commence their sounds if they have those types of decoders. They'll also get your Paged/Service Mode programming address changes and everything else. Not good.
So, you need some positive way to keep your one needy engine strictly isolated, and that means some mechanical way to prevent the inadvertent programming by bridging. You need a block at each end beyond which the engine can't go, or you need a dead length of track as more insurance. The longer that length of dead track, the more likely you'l need to feed it separately to restore full function to engines, particularly small ones, needing to cross that length of track.