Installed a Digitrax DZ123 decoder in a Bachman Spectrum 44 Tonner and got some odd results

Model Railroader General Discussion (Model Railroader)
1

I installed a Digitrax DZ123 decoder in a Bachman Spectrum 44 Tonner last night and got some odd results. When the locomotive is placed on the powered track, it starts moving forward uncontrollably at what appears to be full speed. It will not respond to any commands from the command station when on the main line, and is not responding when on the program track.

When installing the decoder, I removed the PC board that came with the locomotive and wired the DZ123 decoder directly to leads from the track, the motor and the lights. I’ve rechecked the wiring and it was done correctly.

My guess is that I got a bad decoder that has an internal short circuit that is allowing power to get from the track to the motor. The lights will also not function. I am curious if this has happened to anyone else.

2

Before you give up. do a ‘reset’ on the decoder and see if that resolves the problem. This will reset all CV’s to defaults and the address will be ‘03’.

Jim Bernier

3

Jim:

I tried to reset the decoder values (I think it’s CV 8). But the decoder would not respond to any CV read or write commands.

4

Is this the newer single motor unit, or the old dual motor one?

Assuming the wiring is correct - red and black to track pickups, grey and orange to motor leads, blue and white to headlight, and blue and yellow to rear light - it should run. If you are getting no response to programming commands, it’s either a dead decoder or miswired, not much else can be wrong.

–Randy

5

I just had the same thing happen with an MRC Diesel sound decoder I installed into a P1K Erie-Built. What threw me was that I had just removed a decoder that was working just fone from that same loco, so I know the loco ran just fine.

Put in on the mainline, and the thing takes off like crazy. To make a long story short, it works like a champ now… The track pickups on the loco weren’t all connected, and I think one was shorting something somewhere or making something just act goofy. I reconnected the track pickups from the trucks back up to the circuit board, and everything runs great. Hopefully your problem is something similar and not a bad decoder.