DCC system debugging

Many newcomers experience erratic operation when starting. Often this is caused by poor installation. Poor installation includes poor wiring connections or techniques, poor decoder installations, etc. "Do it right the first time" is something I cannot say often enough.


Don't assume it is the DCC system or loco! Start at the beginning. You should be tired of me saying this: "The track is the foundation of your layout"

  • Make sure you have good power, MEASURE your voltage and current. . Next find the LEAST COMPLEX way to reproduce the problem. If you can make it happen on rollers on an isolated track section, debug in that environment.

Test with a different loco

Many people test the system with a loco that has somehow gone defective. If you base the health of your system on one loco, it's usually a mistake. Try a second loco.

Check the system by minimizing the variables

Put the loco right near the track feeds

disconnect other track feed

disconnect the track feeds and power a separate 3 foot section of track

use a different throttle

use a hardwired throttle

check your power supply voltage

Packet analyzers

A common issue is that you get erratic operation somewhere on the layout. Usually it is bad wiring, but occasionally it is something else.

This is where attaching a packet analyzer to the rails lets you verify what you are sending is what is being received. Also, some systems just put crappy data on the rails, poor packet timing, etc.


Pricom made a nice portable one, powered from the rails, mono LCD readable in full sun. If you find one of these for sale, buy it! There is some integration with JMRI.


NCE also made a little module to allow looking at packets. It also seems to be discontinued. I have one, but have not played with it yet, some integration with JMRI also.

Arduino - based

Here's one I was pointed to: https://rudysmodelrailway.wordpress.com/2015/10/23/dcc-sniffer-packet-analyser-with-arduino/


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