Atlas MP15 and ESU

[Lackawannae8]

so ive been cramming ESU into my MP15s recently and have been annoyed by motor preformace with 3 pt table and speed curve tables has anyone experienced the wobbly or jerky ish motor effect? i dont run fast at most cv5 would be 125-160 at most. looking for ideas here I believe I tried auto tune in the past and the results were trash.. I wonder if im basiclly SOL?

[tehachapifan]

As much as I LOVE ESU decoders, I agree that the auto-tune feature is basically useless. That said, without it you are kind of stuck with throwing #### at a wall and seeing with sticks with regards to motor parameters, BEMF and such. Still, I'm certain that you can eventually get it running like a Swiss watch. Do you have a LokProgrammer?

[Jim Starbuck]

My experience when an engine is jerky at slow speeds with an ESU it’s due to BEMF settings.
Try looking at CV52 and try it at around a value of 5.
Try CV51 at a value about 8 and see if that changes anything.

[Lackawannae8]

As much as I LOVE ESU decoders, I agree that the auto-tune feature is basically useless. That said, without it you are kind of stuck with throwing #### at a wall and seeing with sticks with regards to motor parameters, BEMF and such. Still, I'm certain that you can eventually get it running like a Swiss watch. Do you have a LokProgrammer?

Lokpro is like my best friend and money maker LOL

[jdcolombo]

It's almost certainly a problem with the BEMF settings in the decoder, unless your engine has a mechanical problem.

Let's assume it's a BEMF issue.  The key BEMF parameters are CV's 51, 52, 53, 54, and 55.  If you can read the values of those CV's and report back, it might help isolate the problem.

The standard values for BEMF in a LokSound V5 put CVs 51 and 52 at 10; CV 53 at 130, CV 54 at 50 and CV 55 at 100.  First, check to make sure these are the values in your decoder.  If not, set them there as a start.  CV's 51 and 52 control very low speed performance; CV 53 should always be left at 130.  Jerkiness at higher than a creep speed implicates CV's 54 and 55, which will affect the entire speed range.

So the next question is whether the jerkiness you are experiencing at all speeds or only very slow speeds?  If it is only at slow speeds, then you need to adjust CV's 51 and 52.  If it is all all speeds (or at least at speeds higher than a creep), zero in on CV's 54 and 55 and leave CVs 51 and 52 alone.

Adjustment of these CV's is trial and error.  What I do is start with the factory values, and then try increasing and decreasing those values by large amounts to start with, to see if I get better performance.  Then iterate until you get smooth motor performance.  For example, if I notice jerkiness at speeds above a creep, then what I will do is reduce CV54 to, say, 20 and CV55 to, say, 50.  Is it better or worse?  If better, try increasing each value by 15.  Do this one CV at a time.  E.g., try increasing CV54 by 15 and observe.  Better or worse?  If better, then increase CV55 by 15.  If worse, go back to where you were on CV54 and increase CV55 while leaving CV54 alone.  If increasing the values doesn't help, try decreasing.  Repeat ad nauseum until you have best performance, and as you zero in on smooth performance, reduce the amount you change - I start with increments of 15 and end up with increments of 5.  There is no pattern to any of this; it all depends on individual motor response.  I've had engines where best performance required CV54 at 15 and CV55 at 100.  Others had CV54 at 50 and CV55 at 20.  You can't know until you try.

This will take a while.  Do NOT use the LokProgrammer.  Instead, do all the programming changes with programming on the main so you can immediately observe the results (I make these changes with the engine running at a "jerky" speed so I can immediately see if it is making things better or worse).  Take all other engines off the layout so you don't accidentally screw them up.  Expect to spend 2-3 HOURS finding the right combo.  The upside is that once you figure this out for one of the MP's, you can enter those same values in the others and probably get equal performance with only minor tweaks.  Note the "probably."

I know this sounds awful.  It is.  But if you do this iteration process and keep at it until you find the best combo, you will fix your issue (unless your issue is a mechanical one; the only way to test that is to remove the decoder, wire it for DC operation, and run it on a DC power pack to see if it runs smoothly on DC.  If not, you've got a mechanical issue.)

John C.

[Lackawannae8]

appreciate the responses wont be til next week when I get home from "vacation" and look deeper into the motor programming side of things.

[GGNInNScale]

You might try running in 128 mode if you are only driving at low speeds.