NEW Bachmann Plus HO B23-7 UP Diesel 156 -- WON'T RUN

[BadgerRDF]

I bought a brand new Bachmann Plus HO B23-7 Union Pacific Diesel 156 in the box already set up with Digitrax DH123.  My layout is set up for DC only.  New loco won't do anything on powered track -- do I need to have a digital control unit to make some kind of modification to the programming so it will run on a DC system?  I thought that this loco would run out of the box on either DCC or DC.  Please help.

[rich1998]

Apparently the decoder was programmed to not run via DC. You will have to find someone with a DCC system to modify the proper CV.

Rich

[BadgerRDF]

Thank you for this information.

[Gearedenginefreak]

I have had a few dcc locs that I wanted to run on dc that seemed to not want to run on dc, but they just needed a lot more voltage than expected and so the throttle had to be turned way up to get any response from them.  I expect that for sure from sound units, but it was strange on non sound units. 

[RAM]

Will  Digitrax DH123 run on DC?

[rich1998]

The microprocessor needs five volts DC just to wake up and the loco needs about two volts more to begin to move. Nature of the beast. I think the decoder manual mentions that.
Many have reported this in other forums and has been mentioned here in the past.
There is a CV that can be shut off because a decoder can run wire open on DCC sometimes under certain conditions is why some turn off the DC option.

Rich

[emde5]

The DH123 is an old decoder.  No longer produced.  The decoder manual states it does run analog, but will take a lot of volts to get moving.  Was not put in Bachmann locomotives as a stock decoder.  Bachmann used a modified Lenz decoder and a modified Soundtraxx decoder.  Some Spectrum steam came with full Soundtraxx.

[jward]

In my experience with the DH123 decoders, they DO run on DC as factory default. However, if you are running DCC and power is interrupted, sometimes these see the resumption of power as a switch to DC and behave accordingly. After several incidents of locomotives taking off at full throttle with no way to slow them down short of cutting off track power, i reset all mine to DCC only. Problem solved.

I suspect whoever had this locomotive before you did the same. You have several solutions:

1. remove the decoder and wiring harness. This is alot of work as you have to rewire the locomotive.

2. Look for a dummy plug for a JST connector. The Digitrax decoder plugs directly into the wiring harness using this connector, and Digitrax makes dummy plugs to fit. This will restore your locomotive to full DC operation without rewiring.

3. Do a factory default reset on the decoder. This requires a DCC system capable of programming decoders which i assume you do not have. Even after reprogramming, the locomotive will run sluggishly as the decoder will eat about 5 volts befoer the locomotive starts to move. That is almost half of your throttle arc.

Your easiest option would probably be number 2.