Adjusting start speed

ModelRailroadForums.com is a free Model Railroad Discussion Forum and photo gallery. We cover all scales and sizes of model railroads. Whether you're a master model railroader or just getting started, you'll find something of interest here.


tnolan55

CSXfan96
I have an Sd70mac from athearn genesisand i would like to change the speed step it starts moving at to step 1. I do not know how to do this so I would like some help.
 
Last edited by a moderator:

fast_ian

Member
"Start speed" is always zero! :) [Sorry - Couldn't resist ;)]

What you're looking to change is the start voltage - This is set in CV02, and (generally) defaults to 0.

I don't know what decoder you've got, but I'd try setting CV02=02 and see what happens - If it still doesn't move, you can increase the value of CV02 until it does (On Digitrax decoders at least it can go as high as 255!) - Beware however - Setting it too high will result in it taking off at top speed at speed step 1.....

Once you've got CV02 set, CV06 will set the mid voltage and CV05 the maximum. [Setting CV05 to ~150 slows the the top end down for me such that folk can't pretend they're at Daytona for example!]

HTH, cheers,
Ian
 

fast_ian

Member
...I am using a tsunami tsu-gn1000 decoder.
Hmmm - I had a quick look at the manual and it seems only VStart (CV02) is supported - They simply don't show CV06 and CV05 in their listing.

So, I was correct about setting CV02, but if you want to go further it seems you're going to need to load a complete speed table (CV's 67 thru 94).

Got JMRI?......

Cheers,
Ian
 

Selector

Well-Known Member
I have a BLI J Class with a Tsunami 'heavy' in it. It was jerky at low speeds, and I had CV2 set at zero.

I have learned that with CV2 at 0, put a single speed step on your throttle with the loco clear to run forward close to level for several feet on the rails.

Enter programming on the main, to CV209, and enter a value near 30. Then enter CV210 and enter a value just a bit higher, say 40. You should find that the mechansim smooths out quite a bit. If not, go back to 209 and double the value of 30 to 60, and do the same for 210. At some point your engine's drive should smooth out. Exit, and you should have your engine moving on speed step 1. If not, add 1 or more to the value already in CV2.

It seems involved, but once you do this you will never forget both the procedure and how useful it is. Worked like a hot damn for my slightly jerky and annoying J.
 

fast_ian

Member
Enter programming on the main, to CV209, and enter a value near 30. Then enter CV210 and enter a value just a bit higher, say 40. You should find that the mechansim smooths out quite a bit.
I don't have any Tsunami's, but the above prompted another look at their CV's - 209 is "Kp coefficient" and 210 "Ki coefficient".

Are these "kick start" parameter(s)? Why two?

Cheers,
Ian
 

Selector

Well-Known Member
I have no idea, Ian, not being a DCC guru, but they may also affect BEMF somehow. It would be a good question for the Tsunami interest group on yahoo or someplace like that.
 

diburning

AlcoHaulic
I don't have any Tsunami's, but the above prompted another look at their CV's - 209 is "Kp coefficient" and 210 "Ki coefficient".

Are these "kick start" parameter(s)? Why two?

Cheers,
Ian
I think that's for the BackEMF settings. I don't use BackEMF (unless it's turned on by default) so I wouldn't know.
 

tnolan55

CSXfan96
Okay i got it to work for the sd70 athearn genesis model. but it wont work with my Bachman spectrum with the factory equiped decoder. any suggestions on what to do?
 

diburning

AlcoHaulic
Does your Bachmann have a tsunami or a regular non-sound decoder? The non-sound decoders are what I would consider to be "crippled" (in the sense that theres not much that you can adjust)
 

Cjcrescent

Master Mechanic
I just checked a basic Bachmann decoder on JMRI. CV 2 as well as 3&4 are supported. According to JMRI these decoders support staring voltages only, with no speed table adjustment available.
 

fast_ian

Member
With apologies for the hijack....

... the above prompted another look at their CV's - 209 is "Kp coefficient" and 210 "Ki coefficient".
I have no idea, Ian, not being a DCC guru, but they may also affect BEMF somehow.
I think that's for the BackEMF settings.
So, I couldn't let that rest! They're not BEMF but "related"..

CV209 contains a value between 0 and 255 that specifies a gain factor for the proportional part of the PID motor control equation.

CV210 contains a value between 0 and 255 that specifies a gain factor for the integral part of the PID motor control equation.

CV214 contains a value between 0 and 255 that specifies a gain factor for the derivative part of the PID motor control equation.
Now, if I could find the "PID motor control equation" I'd be happy. I suspect most have gone glassy eyed by now, but I love a good equation! :)

Okay i got it to work for the sd70 athearn genesis model.
Did you adjust CV02? Or did you tweak it as suggested by Selector? Both?

Cheers,
Ian
 




Affiliate Disclosure: We may receive a commision from some of the links and ads shown on this website (Learn More Here)


ModelRailroadForums.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com

RailroadBookstore.com - An online railroad bookstore featuring a curated selection of new and used railroad books. Railroad pictorials, railroad history, steam locomotives, passenger trains, modern railroading. Hundreds of titles available, most at discount prices! We also have a video and children's book section.

ModelRailroadBookstore.com - An online model railroad bookstore featuring a curated selection of new and used books. Layout design, track plans, scenery and structure building, wiring, DCC, Tinplate, Toy Trains, Price Guides and more.

Top