DCC acceleration problem

[rlandry6]

I recently installed a Digitrax DZ143 in an Atlas RS-1. The loco ran fine in DC mode. It still runs very smooth in DCC at all speeds. The issue is that when I go from "brake" to "forward" or " reverse" ( I have the decel/accel spped set at the slowest setting), it accelerates smoothly until it hits a certain spot, does a little jump to a hiher speed and then completes the smooth acceleration. It happens in both forward and reverse, and always at the same point in the acceleration regardless of the location on the track, so I know it's not a track problem. I called Digitrax tech support, and all the guy could suggest was resetting the decoder to the factory default settings, which did not help. It's like it skipping over a section of steps while it's accelerating. I have another Atlas loco with a DZ123 decoder and it runs like a champ. I havn't swapped decoders with the locos to see if the problem moves. They're hardwired and its too much of a hassle. I was wondering if anyone has experienced this and how you resolved it.

Any ideas are appreciated..
Thanks
Bob

[scole100]

I had a similar problem with a MRC decoder. Unfortunately I was never able to resolve it. I eventually swapped it for a Digitrax decoder and it worked fine. Sorry I am no help, but I will be interested to see if anyone does have a fix. I still have the old decoder. I am to cheap to discard it.

[rrinker]

Well, the reset is always the first thing - no matter that the decoder was new in the package, all CV's migth not hae been set to default. But since you've already done that...

You are setting anyting in CV02, CV05, and CV06 are you? That's Start Voltage, Max Voltage, and Mid-point Voltage, respectively. If the response curve is not set to a linear setting, which the defaults will do, you could get a jump at the first step past midpoint both on the way up and the way down. Also make sure Bit 4 of CV229 is set to 0 - no speed table. If you are using 28/128 speed steps, 4 digit address, try CV29 as 36. Use CV29 as 2 if using 2 digit addresses with 28/128 speed steps. Both settings have NO analog conversion and NO speed tables.

There's really not much else that would make the speed steps 'jump' insteadof move smoothly.

--Randy