I am having a problem getting good slow speed control with a locomotive. It runs extremely even and slow in reverse, but when I run it forward, it jerks constantly. Could this be a weight distribution issue? I have removed some heavy components from the rear of the loco. My normal DCC tricks aren't working. A bit of help would be great eh!
JJF
Prototypically modeling the Great Northern in Minnesota with just a hint of freelancing.
Yesterday is History.
Tomorrow is a Mystery.
But today is a Gift, that is why it is called the Present.
Did you check to see if anything is binding mechanically? Also, did you install the decoder yourself, or did it come pre-installed?
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
tstage Did you check to see if anything is binding mechanically? Also, did you install the decoder yourself, or did it come pre-installed? Tom
The install is my own handiwork. I've looked but I can't see anything that would bind.
Hi JJF,
Is this a steam locomotive? If so, I would start where Tom suggested. You may have binding side rods or the wheels might be out of quarter. The best way to make sure the mechanism is running properly (assuming it is steam) is to remove the shell and the motor so that you can push the drive system back and forth on a piece of track.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
The problem is the motor itself. I removed it and it runs smooth one way, and jerky another.
JDawg The problem is the motor itself. I removed it and it runs smooth one way, and jerky another.
My first thought was that you had a gear meashing problem...
Simon
Lastspikemike When directly powered by DC voltage or through the decoder?
When directly powered by DC voltage or through the decoder?
Through the decoder. I am trying my best to turn off BEMF, because the motor spun nicely before conversion (DC power), but now.... I can't get CV 49 to the correct value to turn it off. . As of now my options are BEMF on, (aka the miniature engineer rides the bucking bronco) or trying to remotor a motor that performs well!
Not to be obvious... but what happens when you swap leads to the motor with everything else unchanged. Does it then 'hesitate' only in the reverse direction?
If this weren't something only happening on DCC, it would sound to me like a cocked or broken brush, that 'trails' properly in one direction of rotation but hangs up, perhaps on slightly high commutator segments, in the other direction.
You might pull the brushes, look carefully at and perhaps stone and clean the comm, and then put a light filed bevel on the leading edges of the brushes in the 'forward' engaging direction.
There may be something on the armature like a loose wire or tab that is acting like a 'ratchet' as the armature rotates. You should be able to feel this by gently rotating the motor shaft in both directions...
What type of decoder and engine?
Since the motor and loco ran well on straight DC, it's likely the decoder (unless, of course, you did a bad while installing the decoder).
I'm pretty sure there's a "special trick" to do to solve it. If no one here can help, I'd go to the group.io people, and ask them. There's an ESU group, and a Soundtraxx group, 'cause I'm in both.
Oh, yeah. As asked previously: what decoder, what loco?
Sometimes problems go away with a decoder reset. You might have to do it more than once to get things to "stick". Or in this case, "unstick".
I find it very odd that you say you can't change CV49.
Ed
Ok. Couple of point. 1. Walthers Plymout is the loco.
2. Esu loksound 5 micro. 3. I can change the value of cv 49, but then the loco doesn't run. It defaults to 17. To disable BEMF you change the first bit from 1 to zero. Thus a value of 16. Howver then the loco no do the runs!
4. I've done a decoder reset, 5 infact.
5. I will now swap motor leads and see what happens.
6. I know that this is an atypical loco, but that is not the problem here. The motor is a 5 pole skew wound, like many others.
7. Many, Many, MANY thanks to all who submtted a reply. I was about ready to punt the little thing through the window.
JDawg I was about ready to punt the little thing through the window.
Way too early for that, though if you must, punt it in my direction, please.
If you/we can't get it figured out, try:
https://groups.io/g/Loksound
There's some good people there who know things.
JDawg3. I can change the value of cv 49, but then the loco doesn't run. It defaults to 17. To disable BEMF you change the first bit from 1 to zero. Thus a value of 16. Howver then the loco no do the runs!
These conflated CVs use the position of binary digits as individual settings -- remember the inchworm song? That "16" represents the binary digit in a particular position... ESU makes a note about this in their discussion of these multiple CVs. ISTR there is a big vs. little endian convention of bit order here, at least potentially, although I apologize in advance if you know how this works.
The 'value' of the CV, which is the thing you see reported, is the decimal equivalent of the individual bit 'switches' added together in positional notation, so that '17' represents a 1 in the positions for binary 1 and binary 2-to-the-4th but a zero for all the others (see the thread about turning the prime-mover start sequence on or off and note what the difference between 0 and 16 vs. 4 and 20 actually represents).
Look at the manual to see what is packed in CV49 and set the bits accordingly, then see what the decimal equivalent ought to be.
7j43k JDawg I was about ready to punt the little thing through the window. Way too early for that, though if you must, punt it in my direction, please. If you/we can't get it figured out, try: https://groups.io/g/Loksound There's some good people there who know things. Ed
You're right of course. I was adjusting cvs all afternoon with no luck so I was a bit frustrated.
JDawg2. Esu loksound 5 micro. 3. I can change the value of cv 49, but then the loco doesn't run. It defaults to 17. To disable BEMF you change the first bit from 1 to zero. Thus a value of 16. Howver then the loco no do the runs!
According to the LokSound 5 manual on the ESU website, the default value of CV 49 is 19, not 17. That would have bits 0, 1, and 4 set. By chnaging it to 16, you turned off bit 1 as well as 0. The manual does not say what bit 1 is for (it says it's reserved), but maybe that's why it wouldn't run.
Ok. So, after re-examining the Manuel you appear to be correct. Maybe I will swap to a value of 19 and see what happens.
Signing in so I can remember to follow this thread. Gonna be interesting to see if it is the decoder settings and not the motor itself.
Good luck.
Rich
Alton Junction
JDawg Ok. So, after re-examining the Manuel you appear to be correct. Maybe I will swap to a value of 19 and see what happens.
If you want to try it without bemf compensation try a value of 18, that would turn off the bemf compensation bit (bit 0) and leave bit 1 and 4 on.
Ok, default setting for cv 49 is 17. Programming 19 or 18 defaults to 17 and 16 respectively.
So here is the working theory. The decoder is kicking or pulsing the motor. That is why it is Running jerky. Not going to lie, CV 49 is throwing me
I figured it out!
Hello All,
JDawgI figured it out!
And...
"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"
Manuel chapter 11.1.3 titled EMF measurement principle. Basically the decoder cuts power and measures the EMF voltage. That is why the motor stops and starts. I played around with CV 116 and depending on the value, the motor stopped for a longer or a shorter time.
Problem is far from fixed but we are making progress.
The loco now runs perfectly in reverse, but going forward it stalls?, catches?, anyway it stops rotating and hums. Can't see any obstruction,
Update, I marked the motor and it always stops in the same spot. Note, I don't think that this was totally the problem, more of a contributing factor.
JDawgManuel (SIC) chapter 11.1.3 titled EMF measurement principle. Basically the decoder cuts power and measures the EMF voltage. That is why the motor stops and starts. I played around with CV 116 and depending on the value, the motor stopped for a longer or a shorter time.
JDawgProblem is far from fixed but we are making progress.
Good to know!
Thanks for the update!!!
Hope this helps.
Update to the previous updates update...
Going to let motor run for a while. See if the trouble grinds itself out. Thanks for everyone's paitence and help. This has been my most difficult install by far
JDawg ...the motor spun nicely before conversion (DC power), but now....
...the motor spun nicely before conversion (DC power), but now....
I wonder at the point of seeing "if the trouble grinds itself out."
In DC, there was nothing to "grind out", since it ran well. If there IS something, it would have to be something you did while you were working on the conversion.
It ran fine before you did it.
One problem is that according the Loksound 5 manual, there are 10 different CVs whose settings affect load compensation. For example, it says lowering the value in CV 56 can make the engine run more smoothly in the lower speed step range.
This may be an example of where having Decoder Pro would be a great help, as you most likely could just like uncheck a box to turn off BEMF and Decoder Pro would do the calculation of what goes into what bit for you.
Of course, since you said you installed a Loksound decoder, maybe you already have the LokProgrammer set up? That's almost a necessity with ESU sound decoders.
Otherwise, page 72 of the Loksound 5 manual (11.1.4) explains how to do the "Automatic calibration of the motor" where the decoder basically sets itself. Might not hurt to try that and see. Otherwise, CV 49's default value is 19. Maybe just do trial-and-error; set it at 0 and see what happens, then 1, then 2 etc. and see how it goes. Or turn the other BEMF related CVs like 53-54-55-56 to zero and see if that shuts it down.
7j43k JDawg ...the motor spun nicely before conversion (DC power), but now.... I wonder at the point of seeing "if the trouble grinds itself out." In DC, there was nothing to "grind out", since it ran well. If there IS something, it would have to be something you did while you were working on the conversion. It ran fine before you did it. Ed
In dc the motor spun much faster, not allowing the catch. After running it a while, it is improving.
wjstixThis may be an example of where having Decoder Pro would be a great help, as you most likely could just like uncheck a box to turn off BEMF and Decoder Pro would do the calculation of what goes into what bit for you.
As has been suggested, download DecoderPro for your computer; Mac, PC or Linux.
Open DecoderPro, add a loco and assign it the decoder you are using from the list of folders. When opening the program you might get an error message saying that you are not connected..." disregard this.
You will need to assign it an ID like "ESU Test" (upper right).
Go to the "Open comprehensive programmer" (lower right).
Once the programming pane opens, look under the "Motor" tab and turn BEMF "Off".
Then go to the CVs tab and look for the value in the CV(s) you want to change. Hint: look for the CV(s) that are highlighted. Those are the values you are looking for.
Use your throttle to change those CV values as you would normally.