Motor Control - CV Settings

[russ daley]

I understand there are many variables, but curious where you guys and gals who run the older (2000-2005) Spectrum 2-8-0's and 4-6-0's, with no sound and on a 28 Speed step mode, set CV2, CV6 and CV5 for a realistic speed? I also have some engines that have decoders in them with CV6 identified as Page/Pointer Register whatever that is...I'm slowly replacing them as I believe they are giving me issues like stalling...speed changes...etc.

Thank you...     

[jward]

Would these perhaps have the Bachmann factory installed decoders? The ones used in the diesels do not support CV5 or CV6 so setting a speed curve or slowing their top speed is not possible. To be able to do that you;d have to replace the decoder with one that supports those CVs.

[russ daley]

Lenz 1025 Gold...They are probably 20 years old...Anyways, I replace two engines today with brand new decoders, engine performance  greatly improved with Factory Defaults. I just wanted to make sure that my settings were adequate in a few existing and I was getting full benefit of a speed curve. For several engines, I was setting Start Voltage at 3, Mid Voltage at 175, Max at 250. Results were acceptable.     

[jward]

My approach was to take a benchmark locomotive, run it at top speed over a timed course to calculate its speed in scale mph, figure out where I wanted top speed to be as a percentage of that (i.e.100 mph actual versus 50 mph desired + 50%) then adjust cvs 5 and 6 to that percentage. Test run to see how it performs, then make any adjustments from there. Once that was done, I'd do the same to the rest of the fleet, and tweak them so they ran at exactly the same speed as the benchmark loco. I run diesels mostly, so speed matching is necessary to run consists. For steam, unless you intend to doublehead them it's not as critical that they perform exactly alike.

[russ daley]

Thanks for the input...I was thinking along the same line of thought...I just wanted to assure I wasn't missing something that would hinder performance. To be honest...and to obtain realism, if the train looks like it's going to fast...I slow it down. 

[Tenwheeler01]

I got tired of having to adjusting v.start to get a loco to start moving at speed step one.

So I switched out all my old decoders with ones that have "locoMotion" or "hyperdrive" I have not had to mess with the speed tables or starting voltage if I turn on BEMF. And these new decoders have the ability to use a F button to switch between "Switching speed" and "Mainline speed"  Now some times I have to tweak the BEMF settings.  This has only been with one of my very old Spectrum 2-8-0s.  All my locos start creeping at speed step 1 with default motor settings.   And if you want you can set a top speed.  And on some decoders if you turn on speed tables it turns off BEMF. 

       

[trainman203]

This will work for any sound value engine, and for Tsunami before series 2 (light steam, medium steam, heavy steam)

1.  Get engine on a track controlled by a system that can change cv settings (no EZ Command)
2.  Set cv 2 (starting voltage), 3 and 4 (momentum), 209 and 210 (motor control) to 0.
3.  Set throttle to step 1.  Engine won't move yet.
4.  Try gradually increasing cv 210 value until engine barely starts to move.  It will be jerky.
5.  Slowly increase cv 209 value until jerkiness smooths out.
6.  Set momentum values for smooth start and stop.  I like cv3=50 and cv 4=35 but you may want more or less, experiment.

At this point that baby ought to start and stop silky smooth and crawl like an ant.

If things get catawampus you can always reset with cv8=8 plus track power interupption.

[trainman203]

On the newer tsunami 2–2 and Blunami decoders, I found that the following actions work fairly well.

Leave CV 9 at 48 for the moment, set 210 at 10.  Try 211 at 120 and 215 between 51 and 75.  You can run these up and down till you get the engine where you want it, I found slight variation between my engines with these CVs. You can also drop 212 down a little bit from 255 to maybe around 220.  After all of this, you may find that you need to raise CV 209 to above the default 48. I've had to set some of my engines higher than that. Only through trial and error will you find the right setting for that.

When you get these settings right, I have found the switching speed function to be very unnecessary.

And as aside, F9 is a pre-programmed grade crossing signal.  I don't know who is so lazy that they had to program it so that you don't need to press the whistle button a couple of extra times, but I believe that the coupling crash should've been down in those lower numbers instead of something ridiculous like a Whistle signal function for lazy people.

[Tenwheeler01]

Trainman203 thanks for given the info on how to adjusted the BEMF setting.  (I use Decoder pro So I have to hover over the description to see the CV numbers).
 CV 209 is Motor Kp Coefficient
 CV 210 is Motor Ki Coefficient
 CV 211 is Low-Speed Compensation
 CV 212 is BEMF Feedback Intensity
 CV 215 is BEMF Reference Voltage

I have found that the defaults work very will with most locos.  But the older Spectrum 2-8-0 is a bit jerky at speed step 1 on the defaults setting for the TSU2.

[trainman203]

The motor control CV defaults on the older decapods with DCC/sound on board were terrible.  The engines ran horribly and couldn't pull a thing because the CVs were all fighting each other.  Once they were straightened out using the method I outlined they were beautiful performers.  What I don't know is why they couldn't have been set correctly at the factory.

The consolidation was a little better, but once you tuned it up as per what I posted, they were beautiful, would crawl like an ant.