Trouble Shooting A Digitrax DH123AT Decoder

Model Railroader Electronics and DCC
1

I installed a Digitrax DH123 AT decoder in my 2-6-2
Put it on the programming track and let DP read the decoder type

It correctly ID’d the family of decoders
I changed the address to 200
changed the momentum to 10 each
and set up a speed curve at 100 top with matched ends

But when i tried to run it i got nothing on 200 or 03

I took it back to the table and unplugged the decoder and used a 9 volt battery
when i connected it to the orange and grey wires on the plug it ran
I checked for continunity from the track all the way to the plug and it was good, same for the tender wires

This morning I reset the decoder to default
then checked CV 29 and it was at 6 as it should be but when i tried running it
Nothing !

Any ideas ?

2

In order to run on your new address of 200, CV29 needs to have a value of 34. With CV29 set to the default value of 6, the loco should run on default address of 3. If it doesn’t, something is amiss with your installation or you have somehow destroyed the decoder.

Plugging that 9 Volt battery to the decoder’s orange and gray motor output wires possibly destroyed it because you were applying voltage to electronics circuits that are designed for voltage output only.

3

You miss understood

I unplugged the decoder and used the female plug that connects to the loco

to apply power to the motor

See photo

The decoder is plugged into the male 8 pin harness in this photo

I know better than to apply the nine volt to the decoder

So what we know so far is

1 the decoder is getting signals from decoder pro

2 the loco is wired correctly to the female plug on the loco

3 The pick ups are good from the wheels to the plug on both the loco and the tender

4 When on the mail line whit power on the zephyr shows no shorts

4

Set Cv 29=34.

And, for symantics, you just have a DH123, not the AT. The AT refers to the clip that is soldered to one of the motor leads…so just a plain DH123.

David B