NCE D15SR decoder: Not what I expected

[tstage]

Hi everyone,

I am trying an NCE D15SR decoder in my Proto 2000 H10-44 switcher.  However, I'm having a difficult time getting the switcher to run at prototypical switching speeds.

Previously, I had a TCS T1 decoder in it and it ran very slowly at speed step 001.  (I wasn't crazy about the buzzing of the T1 when running it in BEMF mode so I thought I'd try a NCE D15SR.)  Even with the Vstart (CV2) set at "0", speed step 001 of the H10-44 with the D15SR is probably in the 8-10 sMPH range.

I've gone down most of the list of things to adjust, as listed on pg. 3 of the manual:

• Vstart (CV2)
• Torque compensation kick rate (CV116)
• Torque compensation kick strength (CV117)
• Vmax (CV5)

However, any changes only speed things up and the best result are when the above is set to the default of "0".  I also have the Power Cab throttle set to 128-step.

Any ideas of what I'm missing?  It's just too quick out of the gate.  Thanks.

Tom

[cacole]

CVs 116 and 117 set to anything higher than 0 is giving the motor a lot of starting voltage kick.  Try CV 3, Acceleration, to slow down the engine's jack-rabbit starts.  Start with a value of 8 and increase from there as necessary to slow down the locomotive.

[tstage]

cacole

CVs 116 and 117 set to anything higher than 0 is giving the motor a lot of starting voltage kick.

Thanks, Chuck.  Yea, that's what I quickly found out.  I did try Vmid (CV6) and that did seem to help some.  However, it's still nowhere near where I'd like it to be.

I also installed the identical decoder into an Athearn RS-3 and it has the opposite problem: It doesn't start out till speed step 015.  I'm wondering: Is it partly due to different gear ratios?

Tom

[cacole]

For the Athearn RS-3 you need to increase the value of CV 2, Start Voltage.  This could be related to the gear ratio, but my guess is that it has more to do with the quality of the motors used.

[tstage]

cacole

For the Athearn RS-3 you need to increase the value of CV 2, Start Voltage.

Yea, I was going to do that but it was late so I had to get to bed.  I'll play with it more tonight when I get home.

Tom

[rrinker]

 Hmm, my one Stewart F7 still had a D13SRJ in it and it ran great at slow speed. Not sure what I had set for the various motor control things, but that's the place to look. If it moves on step 1 with CV2 at 0, adjust the kick strength and rate for smooth slow operation. Not much to do but play around with it.

 The only other non-BEMF decoder I had was in my Walthers FA, I had an old TCS T1 from before they had BEMF, it too ran great, but for consistency sake I repalced it with a newer one. Obviously I had messed around a lot with the dither settings to get it to run smooth, because when I turned off BEMF it ran horribly on the default settings.

 I'm sure thre is actually some science to this, however since we are not privy to the code used in the decoders to know EXACTLY how the user configurable values are used in regards to motor control, it's tough to do more than just adjust and adjust until it works the way we want. Luckily there is Ops Mode programming.

                               --Randy