Cannot change address w/Digitrax

[pdlethbridge]

there goes another headache

[Yampa Bob]

Paul,
Consider yourself lucky...I could have wrote "the reciprocal of the sum of the reciprocals of the individual resistors,  or the product of 2 resistors divided by the sum". I started to but I know you prefer pretty pictures.   

[Jim Banner]

No, I haven't measured the resistance looking into a decoder from the rails.  I suppose the key resistance would be right at the point where the decoder applies power to the motor to acknowledge the CV update.  As far as minimum resistance is concerned, there would be two values - one below which the acknowledge pulse would be too low to read the other below which the programming circuit would be damaged.  For the Zephyr (DCS50) and the Super Chief (DCS100) the latter resistance would be zero.  The programming circuits are protected against short circuits.  They are not, however, protected against other current sources, such as the running track.

I have had no problems so far programming a Tsunami TSU-1000 with my Zephyr running barefoot.  Or with reading it back.  I don't know if Soundtraxx has made some changes or if the first batch of Zephyrs was more sensitive reading back.  All I can say at this point is that so far it works.  Same with the large scale QSI decoder, another nice noise maker.  The manuals are a bit of a killer.  Between the user manual and the technical reference manual, it was something like 270 pages.  The Tsunami is not quite as bad at about 150 pages.  No wonder people are installing these things and changing nothing but the address.

Jim

p.s. for those born in the latter half of the last century, "running barefoot" is a CB radio term meaning "running without a booster."  Some CB operators ran "a full gallon" which was a one kilowatt booster, a whole lot more power than the legal maximum of 3 or 5 watts.  With that much power, you could drown out everybody within a ten mile radius.  I got a bigger kick out of "working skip" (bouncing signals off the ionosphere) from northern Alberta down to Texas and Louisiana (about 2000 miles) with a 3 watt mobile rig.
J

[WGL]

 Thanks Bob & Jim!  All is clear to me now.

[Union Jack]

Recently acquired the 44 ton switcher w/DCC and could not change address with my Digitrax system.  I found this thread, picked up a 1000 ohm resistor, took the advice regarding alligator clips and walla I'm a happy camper.  THANX much!