# CV values for a HO Spectrum 4-8-4 J with Tsunami Sound?



## RT_Coker (Dec 6, 2012)

I have a HO Spectrum 4-8-4 J with Tsunami Sound that was purchased used and had CV values that had been changed by the prior owner. I was happy using it the way it came; until I started using it on a downgrade at less than maximum speed. It speeds up and then slows down when going down a ~3% grade, at ~2 second cycle. It is enough that the passenger cars are doing a very unpleasant in/out dance.

I am hoping that someone knows the CV settings that will stop or at least reduce this downhill oscillation in speed. Thank you in advance!

I have no way to read CVs, so I reset the sound decoder (CV8=8). But this is apparently a general default and not what I would expect to see delivered in a new unit. I have set CV113 to 120, and like this “Quiet Mode” setting. I then set CV3 and CV4 to 64. I like the acceleration setting, but was surprised to find the deceleration noticeable different.

(The default setting information I have seems to be correct. It gives:
BEMF_CUTOUT 0 /* CV 10, Back EMF Cutout */
/* BACK EMF CONTROL */ 
KP 25 /* CV 209, PID Kp Coefficient */ 
KI 20 /* CV 210, PID Ki Coefficient */ 
KD 0 /* CV 211, PID Kd Coefficient */ 
BEMF_INTENSITY 255 /* CV 212, BEMF Feedback Intensity */ 
BEMF_SAMPLE_PER 15 /* CV 213, BEMF Sample Period */ 
BEMF_APERTURE_TIME 15 /* CV 214, BEMF Sample Window Size */ 
BEMF_GAIN 0 /* CV 215, BEMF Gain Coefficient */
)

Bob


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## NIMT (Jan 6, 2011)

Bob,
If you go on Soundtraxx's website you can download all the variables.
Unless you have a enginering degree you need to leave these values at factory settings.
KP 25 /* CV 209, PID Kp Coefficient */ 
KI 20 /* CV 210, PID Ki Coefficient */ 
KD 0 /* CV 211, PID Kd Coefficient */ 

Reset on an OEM Tsunami is CV 30 = 2

Setting thew BEMF will keep it from running away but if it's surging then BEMF is set too high.


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## RT_Coker (Dec 6, 2012)

Thanks!!
I have changed enough CVs that I don’t think this is a problem of not using the right CV values; but because I can’t read CVs I won’t argue this. It will probably be a good while before I have a CV read capability and enough spare time that I am willing to use to research HO motor control. So I will just be limiting this loco to high speed down grade runs for now.
Bob


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## NIMT (Jan 6, 2011)

Pm me when you want to be able to read the CV's. I sell the programming track booster to do that.


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