Hello,
I just installed a Digitrax SDN144PS N scale decoder in my Athearn HO 1500 switcher. I am using a Zephyr Xtra for the command station. The problem I have is that the decoder lags the throttle commands. When I put the throttle up, it takes just under a second to start responding and then when I go to stop from a medium/high throttle setting, the loco continues for about 2-3" before stopping. It says that it includes a 330uF capacitor, but when I opened the package one was already installed. Red instead of blue and physically smaller than the 330uF. The track is clean and to double check it, I ran a few locos with various decoders in them around and they all function normal. Any idea what could be causing this lag from command to actual movement? Thanks for any help.
Check and make sure CV3 and CV4 are set to 0. CV3 is acceleration momentum and CV4 is deceleration momentum. Values here cause the loco to speed up or slow down slower than you move the throttle.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
What I was going to say. Great suggestion.
What I do not understand is why Digitrax has not corrected this problem. I had installed a SDN144K1E into a Kato SD40-2 unit. When I blew the horn the unit would stop and reset- So I had to turn off the BEMF (CV57 set to zero), At least now whenever I blow the horn the unit does not stop and reset. I also had very poor running with this unit, it would run and then stop. Very picky about clean track, the slightest bit of dirt or debris would cause the unit to sop and then restart. I have noted that the description states that there is a 330 uF capacitor with the decoder. The one I installed had a 100 uF cap. I figured Digitrax figured that there was no way you were going to get the 330 cap to fit and went to the 100 cap. Still the cap is too large to fit into the SD40-2 that I worked on. I switched to a surface mount 100uF. Not sure if the difference of the capacitor capacity size made the problem of stopping and resetting. So I guess that this is a problem with all the SDN144 decoders? Why have BEMF a feature that you must turn off?
What I do not understand is why Digitrax has not corrected this problem.
I had installed a SDN144K1E into a Kato SD40-2 unit. When I blew the horn the unit would stop and reset- So I had to turn off the BEMF (CV57 set to zero), At least now whenever I blow the horn the unit does not stop and reset. I also had very poor running with this unit, it would run and then stop. Very picky about clean track, the slightest bit of dirt or debris would cause the unit to sop and then restart. I have noted that the description states that there is a 330 uF capacitor with the decoder. The one I installed had a 100 uF cap. I figured Digitrax figured that there was no way you were going to get the 330 cap to fit and went to the 100 cap. Still the cap is too large to fit into the SD40-2 that I worked on. I switched to a surface mount 100uF. Not sure if the difference of the capacitor capacity size made the problem of stopping and resetting.
So I guess that this is a problem with all the SDN144 decoders? Why have BEMF a feature that you must turn off?
I also have that Digitrax decoder, and after the issues I have had with the SDN144KE and the SDN144PS, I will never buy another Digitrax decoder again.
I would not either. There is such a demand for sound decoders for the narrow hood diesel locomotives that people buy these or the MRC units as they are the only game in town.
The new QSI Titan series decoder is supposed to be a better decoder, but are just now hitting the dealers shelves. So I have seen no feed back on them at this time. They took a long time to get this product to the market.
A lot of people don't like the hard-wired decoders, especially in a tight space in a diesel. I prefer a drop-in decoder to diesels, but that's just me.
Yes, David I have seen the Sourroundtraxx in action. It did slip my mind. Might be a better way to go in the long run. Hard to dig up the funds to purchase has it is a large investment.
thanks for the posts. I have been trying and trying to fix this thing with no luck. I think I might just get a different decoder and give it a try. I set CV 3 and 4 to zero then tried BEMF off (CV 57 to zero) and it was even worse. Very erratic. would lurch forward and back then work normal, then stop and not respond to commands. sometimes when I put the throttle back to zero it would just keep going for a couple more feet then finally stop and then stop responding again. I tried other locos to make sure it wasn't the track and they ran with no problems. I also thought it might be the connections on the loco since they have those cheap plastic clips instead of solder so I soldered all motor and pickup connections, did a reset on the decoder and still same thing. just erratic, jerky ops. tried again to set cv 3, 4, 55, 56, and 57 to zero and same thing. This decoder just seems to not want to work. thanks again for the help!
Jerky operation like that usually means dirty wheels, tracks, or pickups. Or poor contact, but soldering all the wires instead of using the plastic caps should solve that issue at least.