Bachmann NScale HHP8 Decoder Problem

[herc driver]

I just set up my Digitrax Zephyr DCC system last night.  When I tried to either "read" or "overwrite" the factory set 03 address on the HHP8, the system couldn't do it.  I consistently received an error message that said there was a problem "reading" the address.  I was trying to change the decoder address to the engine's 4-digit road number, but wasn't successful.  No matter what programming track I used (just in case it was a track issue) I couldn't read the decoder.  I continually received an error that said there was an electrical problem with the programming track/decoder/engine.  But using the 03 address, I could use the engine on the layout and all functions (speed, direction, lights) worked fine. 

I really need to change this engine's address because I'd like to buy another one with a different road number.  I can't have two engines with the factory set 03 address.  Has anyone else had this problem and what was the fix? 

[Conrail Quality]

Try putting a 1000 ohm resistor across the rails when programming it. Bachmann decoders usually cannot be read by a Zephyr without one (the decoder does not draw enough current for the Zephyr to acknowledge it).

Timothy

[herc driver]

Thank you Tim for the quick reply..........just wondering when the Bach Man might shed some light on this as well. 

Forgive my electical ignorance, but let me make sure I get this; I need to place a resistor (one lead touching each track) to add resistance to the overall decoder/resistor/track programming track so that the Zephyr's electrical signal will be "stepped down" enough to actually realize the decoder is there?  Well...then how does the Zephyr "see" the HHP8's decoder when it's on the layout now?  As it is now, I can run the HHP8 on cv03 and everything works just fine.  It is also recognized by a seperate "jump" cab.  Why wouldn't the programming track discover the decoder when the layout does?  I understand the programming track doesn't carry the same electrical load to make the train move - just read the decoder.  (As a side note, when I was first trying to change the decoder address, the engine started moving when I entered the "programming" program.  It did that maybe three times, and each time I powered everything off while the engine tried to move down the 10 inch flex track programming track.  It hasn't tried that since...but I can't understand why it tried doing this or why it hasn't since.  Additionally, I've successfully programmed two other decoders (a Lenz and Digitrax)...so at least I've proven to myself that I can follow the directions in the manual.)

This is probably an obvious answer to anyone in DCC for a while...but I've got a total of 16 hours experience and haven't found the answer in any written material (either in the manual or online). 

Thanks again Tim for a "fix" for this.  Are there other Bachmann decoders that have this problem too?

[taz-of-boyds]

Herc driver,

For normal operation the DCC power pack only sends commands and has no idea if the commands have been received by the addressed DCC decoder, the commands are sent repeatedly.  I took a quick look at reading CV's and what might be the issue of needing an additional load on the track for reading CV's.  But that will have to wait for another day.  Unless you get a reply from some of the other guys.

Charles

[herc driver]

Again - I sincerely appreciate the info - thanks!  Unfortunately, Digitrax sent me two Zephyr Starter Manuals and omitted to send the Decoder Manual, so whatever decoder knowledge I'm gaining is coming from the internet and the more knowledgable people like yourself on the forums.  I just downloaded the Decoder Manual from the Digitrax website so I'll read it and see if there's anything regarding this error in programming a decoder.  I'm hoping to get a "fix" for this, so I'll make the trip to Radio Shack for that resistor and try Tim's idea out.  Hopefully, the Bmann DD40AAX I've got on order with "DCC Installed" won't have this problem...but I'm not betting on that.

[herc driver]

Update!

Thanks for your idea about adding resistance Tim - It worked!

I didn't have a 1000 ohm resistor lying around, but I did have a Bachmann lighted Amtrak passenger car.  So I added length to the programming track and placed both the car and engine on it, went through the reprogramming steps, and successfully changed the engine's cv 03 address number to the engine's road number on the first try!  Thank you very much for that suggestion...your idea fixed a problem!   

[Conrail Quality]

I'm glad I could help. This comes up every few months or so (usually in the HO forum), and it seems to be a problem exclusive to Bachmann decoders and the Digitrax Zephyr. Most other combination seems to work fine. I'd like to be able to explain why this happens, but I really don't know.

Timothy

Edit: According to Jim banner on the HO forum, the problem is that the Zephyr cannot read the acknowledgment signal from the decoder to the Zephyr without the resistor.