I started a thread in the Layouts Forum a few days ago about some Intermountain F3 locomotives equipped with Digitrax DZ143PS decoders that seem to run way too slow compared to F3 locomotives equipped with other decoders.
After receiving several replies, some of which mentioned CV values as a potential source of the problem, I decided to start this thread in the Electronics and DCC Forum to focus on the CV values of this particular decoder. I am attaching a list of default CV values for the DZ143PS decoder which have been summarized in a Decoder Pro chart.
Of particular interest are CV54 to CV57, scaleable speed stabilization values, CV67 to CV93, speed table values and CV94, maximum speed table step.
Could any of these CV values restrict the speed of the F3 loco, causing it to run slower than expected?
I would appreciate your comments.
Rich
Alton Junction
bavrail gave you the best answer. When running Digitrax decoders in consist program a value of CV57=102 into every decoders. I would reset the decoders to default and start with this setting first and go from there.
Jack W.
You probably have scale speed motors in the IM units that run slower than units with regular speed motors. I have several locos, Diesel and steam, that run slower at top speed than other locos from the same manufacturer. I only adjust CV's 2,3,4,5,and 6 when programming speed settings. I don't think that adjusting the values of 106 CV's is necessary and probably is only done bya few nit picking, rivit counting perfectionist freaks. I know several people who have those IM locos and they are happy with just programming the CV's I mentioned.
jalajoie bavrail gave you the best answer. When running Digitrax decoders in consist program a value of CV57=102 into every decoders. I would reset the decoders to default and start with this setting first and go from there.
Yeah, that comment by bavrail was in the other thread in the Layouts Forum.
I found this article on the Digitrax web site, and it discusses CV 55, 56, and 57 in detail.
http://www.digitrax.com/tsd/KB902/scaleable-speed-stabilization-back-emf-in-digitrax/
I am becoming more convinced that the decoder settings are holding this loco to slower speeds.
Top speed with BEMF turned on will be slightly slower than without it - some headroom must be maintained so that the speed can be increased if the load increases. All you have to do is set CV57=0 to turn it off completely and try that. You're already slowing down under load though so there might not be any more to give. And without BEMF, slow speed performance will suffer. And if you aren't going to use BEMF, then save the money and get a cheaper decoder like the NCE D13SRJ. Try one with GOOD BEMF, like TCS, or a Lokpilot. Not sure I trust that the new 6 series decoders from Digitrax have improved on their less than steller BEMF implementation, they claim to, but I've been very happy with TCS and have no reason to use anything else at the moment. Nice thing about TCS is you get BEMF at startup but it drops off at higher speeds so no 'cruise control' effect at road speed.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I don't buy or use Digitrax decoders just because of the complication they have built into the product.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
There are no 'complications' in Digitrax decoders. Just a rather poor implementation of BEMF, at least up to the Series 5 decoders.Primary problem is grouping all the rounding error you get trying to do precision decimal math with a binary device into two spots in the speed range, resulting in rather noticeable jumps in speed at two certain points of the throttle range, which never goes completely away no matter how much you adjust the BEMF parameters. Turning off BEMF solves it, but then why would you pay the extra money for a decoder with BEMF if you aren't going to use it?