Digitrax DCC

DCC system

I don't have a lot of comments on this system, their early radio control was simplex, i.e. one way from the throttle to the command station, and you had no idea if your commands reached the system or not.

The screen has fewer characters than the NCE and the commands are more arcane.

One thing I learned is that you need to remove the battery from the unit to keep it from running down when not plugged in. Some people reverse the contacts of the battery, which apparently works, but sometimes they swap the battery left to right, and the springs that keep the 9v battery against the contacts will short out the battery and melt your case in the process.

Again on the simplex radio system, you must plug the throttle into the throttle bus cabling system in order to acquire a locomotive. Man, I did not realize this years ago when I made my decision between NCE and Digitrax. That is just nuts. Now I know why people walking around with the throttles always had a 1 foot cable hanging out of the top.

To be fair, I need to see if the more modern duplex radio needs this, probably not.



Z Scale decoders

DZ123Z0 - for certain AZL diesels

Top view..

DZ123Z0 top


Bottom view


DZ123Z0 bottom


 measured contacts on stock azl board, 0.027" thick.

You can see the solder blobs on the top side of the Digitrax board, which measured about 0.034".




DZ123M0 - 1 amp, 1.25 amp peak, 2 function, 500 ma

one we worked on was firmware version 51, went into a GP7






drop in decoder for MT GP35, MT GP7

3 speed step tables, bemf,


installation tip, this decoder JUST fits, and requires some modification of the stock "posts", which is not mentioned in the manual.


CV6 = mid speed

CV8 = 8 does reset

CV54 = 1 sets switching speed to be controlled by F6 (set to 0 to disable) speed is reduced by about 50%, and momentum by 25%.

CV57 controls bemf, 0= off, 15 = maximum




This is a quad stationary decoder. It's been around for a while, is reliable and a reasonable price. Handles both impulse, and steady state turnouts, and can be programmed fairly easily.


The nomenclature in the manual may not match what your system "says", and it was confusing to me at first.

closed = 1 = "normal" on NCE

open    = 2 = "reverse" on NCE

Programming options

First you need to decide if you have a constant output or momentary. This is called stall or solenoid type.

Programming for stall motors - option 1

Default from the factory is momentary.

Press the option button about 3 seconds, then the red and green LEDs blink alternately.. select accessory 1 (option 1)  and then closed=1=normal

(open=2=reverse is back to momentary)

Programming reset

option 7, closed=1normal

Programming Turnout addresses

Press id button 3 sec until it flashes, then select the accessory number for the first set of terminals, and either normal or reverse (does not matter)

Repeat for the remaining 3 sets of terminals.

As you program each address, the ID LED flashes faster. After the 4th address, it returns to normal "heartbeat" random blinking.



This is a small, single decoder for Kato Unbitrack bipolar turnouts. It appears to be a pulsed unit. I ordered 3 of them so I will report back.


Weather Underground PWS KCACARLS78