I have been attempting to speed match my fleet of N scale locomotives and the more I delve into it the more confused I get. First off, I have a MRC Prodigy Advanced and almost 90% of my decoders are Digitrax. The group of locos (about 25) I have speed matched work very well together. They start to move at speed step 01. They run pretty close together at steps 02-28. I have them behaving in consists like real locos. This leads me to my first question. Why, after all the work adjusting all these CVs do my locos not act the same when their addresses are dialed up as individual units? It seems as if when dialed up individually, the CV 5 and 6 settings get thrown out and they run as fast as they would without any decoder adjustment. A typical adjustment on my locomotives is SV 040, ACC 003, DEC 003, TV 120 and CV06-065. In a similar way, a typical start voltage setting of 040 makes the loco barely start to move on speed step 01. It provides a full speed range and works well. Problem is, that this again is only when in an advanced consist. When the loco is dialed up as an individual unit it leaps ahead at speed step one. Why is this? The only way I have found to get around this is to run consists of one locomotive. Is this really what has to be done or did I miss something?
It sounds to me like it is your BEMF settings. The simple answer is try programming CV57 to 0. The longer answer: In Digitrax decoders CV57 is the BEMF intensity. If you look at it as a hexadecimal number, the left digit is the value used when part of an advanced consist and the right digit is used when not part of an advanced consist. The default value is 06(hex), so there is no compensation when part of a consist, but there is some when not part of a consist. If you use BEMF you are supposed to program the start voltage to 0. If you do not have it, download the "Digitrax Decoder Manual" from the Digitrax website. It has a lot of information that the sheet that comes with the decoder does not.
I want to thank you Robert for your timely advise. It was exactly what was the problem. The bad news is that every loco I have speed matched will have to be done over again. It seems that when you set CV57 to 00 it throws off the existing adjustments a bit. A small price to pay to now have locos that not only run like prototypes but all run together too. Thanks!
Great to see members helping members like this!!!!!!! :thumbs_up: :thumbs_up: :thumbs_up: :thumbs_up:
speed matching locos is a real time consuming task. just don't think you're doing it once !! depending on how often your locos are used you will match them more or less. drives wear out over time influencing the running characteristics. also almost all engines change their characteristigs in one operating session . a cold loco acts different than one which is warm (after 1 or 2 hours of non-stop running). try to match them as close as possible but don't expect your locos to act the same under all circumstances.
Yes. The first thing I am doing is letting the locos I want to match along with my alpha (target speed) loco do 3 circuits of my layout to get them loosened and warmed up. Most of the drives in my locos need to wear in before they start to wear out. Then I start with the starting voltage to get the locos moving by step #2. Then I go for top speed followed by CV06. After this, acceleration and deceleration are usually a snap.
Removing BEMF does help but you are also loosing a great function, especially important when creeping across multiple turnouts that often slows engines down or even worse, stalls them. A better solution would be a decoder that allows you to limit BEMF to a selectable value above a specific speed step. That would allow you to take full advantage of BEMF at low speeds (very you really need it) and reduce (or remove) it at higher speeds. As to speed matching: A simpler method is used by ZIMO in the MX620 and MX690 decoders. The decoder can be set to actual smph or skph so that each loco equipped with that decoder travels at the exact same speed at a given throttle setting. For example, a throttle setting of “50” would set each loco speed to 50smph, no fussing around with speed tables ;-)
A better option is to program the locos using JMRI. You can save 2 files to your computer, one for individual running and one for a consist. If you put the locos in a consist, load the cinfig in JMRI and do a write all. When you go back to individual running, load the individual file into the program and do write all again. Easy to change, you don't have to write anything down because the settings are stored in the computer file. Plus, you don't have to program in hexadecimal either. Makes life much easier. JMRI- http://jmri.sourceforge.net/
