28/128 is the same setting. 14 steps is different - and causes very obvious issues like the headlight going on and off with alternate steps.
If there is only mild bucking when the locos are coupled together with no train - put a load on them. Having a train to pull, especially one that needs more than one loco to move, smooths out operation greatly as each pulls its weight.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I took the offending unit apart and checked the motor ......it seamed a bit tight.......I was able to work it look a bit ......put it back together so I`ll see if it runs better.........as for the other two.........I think there was an issue with one being set at 28 speed steps and the other at 128.
Dennis Blank Jr.
CEO,COO,CFO,CMO,Bossman,Slavedriver,Engineer,Trackforeman,Grunt. Birdsboro & Reading Railroad
MisterBeasley Is the engine performance jerky only when they are consisted and coupled together? Or do they have the problem when separated?
Is the engine performance jerky only when they are consisted and coupled together? Or do they have the problem when separated?
They are not consisted.......all three are programed with the same loco number.
It takes an iron man to play with a toy iron horse.
They always use PWM. QSI may use that term to describe a mode without BEMF, but to my knowledge every deocer's motor drive uses PWM. There may be some oddballs that don't but is so, only in larger scales, as the components to handle even a 1 amp motor using straight dissipation techniques are much larger than what is found on an HO decoder. PWM in a way 'cheats' to allow smaller components to handle much greater loads than they could stand on a continuous basis.
QSI witht he upgrade chip have standard throttle control (PWM with no BEMF), RTC which uses BEMF to maintain specific speeds per speed step, and BEMF, same thing but not as strong a BEMF so the speeds will vary somewhat with load - this one is not 'cruise control'. I may be off, I'm writing this off the top of my head without consulting the QSI manual, but the manual explains it all - the full manual, not the quick start you generally get with the loco.
Would setting the decoders with PWM help ?
No BEMF may help, but I ran a consist of a pair of Proto Geeps with TCS decoders (BEMF enabled) plus an Atlas Trainmaster (QSI with BEMF) and they ran fine for a week long club show, no jerky motion when starting out and I rarely hit speed step 50 on them.
Digitrax decoders are the only ones I know that have seperate BEMF settings for single or consist, and the consist setting only matter when CV19 is used, so it comes into play when using NCE.
davidmbedardAs said before, the problem is the smooth running drive. Solution? Turn off BEMF. David B
Would that be under CV 56.5 ?
You may need to adjust the speed settings at the lower end. I never expect a set of units to all run at the same speeds until matched, even identical units with the same decoders. Have only found one pair out all I have done that ran the same..
Peter
I seem to remember Randy telling us to disable BEMF when a consist is jerky. If one loco is a bit tight and doesn't move as fast as the other(s) in the consist for a given throttle setting, the others will use BEMF cyclically to slow or speed up, resulting in a conflict that also cycles. They'll fight each other under BEMF, IOW.
Or, so I understood.
Crandell
It could be a back EMF problem. Perform a full decoder reset and then try again. If the jerkiness is still there you could have cracked gears, or they may need lubing.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
Hi all,
I have a 3 unit (ABA) set of Walthers Proto F7`s from a run in 2011.
They are equipped with QSI sound decoders.......version 7.
I noticed that when I run 128 speed steps with my NCE Power Cab and Smart Booster (SB3) that they are jerky up to speed step 50....then they tend to "smooth out".
The wheels are clean........would I need to program Pulse Width Modulation?
Thank you.