bachmann 4-8-2 decoder

[Rick64]

I've spent the last three days trying to figure out how to describe my problem, so here goes. I have a Bachmann heavy mountain with a digitrax DH163P decoder that worked fine on my previous layout. My new layout is in 4 power districts as per the PM42 with one district set for AR, which is district 1. The loco runs fine on district one. As soon as it gets to the double gap to district 2 it stalls and takes short jerky motions, with the PM42 clicking a short. If I crank the throttle (Zephyr) to half the loco takes off and runs through that section of track. The same thing happens on district 3, the yard area. district 4 is not built yet. All of my other locos run fine on the entire layout, including an IHC 2-10-2. I have dropped feeders all over the place, which did help some areas that were weak but had no effect for that loco. My feeders are 20 gauge leading, in some cases to 16 gauge secondary feeders or directly to the 14 gauge bus lines. A possibility I hope is not the answer is that district 1 has solid core bus wire while the rest is stranded and twisted. That would be a lot of work to re do for one loco. Could the decoder have gone "sour" somehow? any thoughts would be greatly appreciated. Rick

[DouglasJMeyer]

Not sure it has anything to do with this case. But I know that some of the bachmann 4-8-2s had wireing issues. They would work on DC but not on DCC. Some of the wires where crossed. I had one that runs backwards as wired (need to swap the wires to the moter on that on) and on that had some wire crossed that ran on DC but the decoder shorted out when you conected the tender to the engine. The sound decoder in the tender worked (and worked when connected to other Backmann engines) but shorted as soon as you hooked it up to the engine. Had to trace the wires on that one and rework it.

So thier may be something funny about the wireing in the engine. Not sure  how that would have the result you are seeing but I do know some really odd things happens with that engine and it's wireing when it is used on DCC. And being as it is only that engine.

Does you system have a way of reseting what is called forward with out having to rewire ot change setting in the decoder. I know some systems used to have that. So if on sections things forward is backward and the other thinks it is the other way each section could be telling it something different or some such. Not really sure how you system works. And this is just a thought.

So anyway while I doubt the above has anything to do with it, I do think you may want to look at the wires on the engine, those are a known issue.

Doug M

[Rick64]

That has certainly given me something to look at. As per your suggestion I will also try resetting the decoder back to original settings. I guess i need to check again just in case I have a feeder out of place somewhere. I don't think so but who knows. thanks again. Rick

[Jacktal]

I'm no DCC guru but the fact that only one of your locos is affected has me thinking.Since it goes fine on section one tells me the loco is OK but it trips on section 2 and 3 while other locos don't....puzzling indeed.OK...here's my theory...could it be that this loco has a higher current draw than the others AND that sector 2 and 3 PM-42's sensitivity is set a little too low.I know that the PM-42 allows specific settings for each of its four districts...just a wild guess.

One quick way to check if it makes sense is to disconnect sectors 2 and 3 from the PM-42 and run them through sector 1 via jumpers between tracks.If everything goes right this way,you have faulty settings or a defective PM-42,wich I doubt since your other locos run fine on all sectors.