Kato N scale FEF TCS DCC problem

I am having issues with slow speed control on DCC. with Factory defaults, speed step 1 is way too fast. Disabling BEMF (Set CV61 to 0 ) makes it run even faster. Setting CV66 (motor trim forward) to 1 actually produces the slowest results (with BEMF CV61 set to 1), but nowhere near a creep like I can get from any of my other DCC locomotives regardless of the type of decoder or company of manufacture. This is my first locomotive on the layout with a coreless motor, and I am not sure if this has something to do with it. Beyond that, the locomotive surges randomly when BEMF is engaged, and if I turn BEMF off, it does not surge, but once again slow speed suffers. This is a beautiful model and does run really well, I just can not get slow creeping starts like I have seen on DCC. I am using a MRC Prodigy advance wireless system, and I have never had a problem with slow speed operation before, even my Bachmann S4 runs incredibly well at very slow speeds. I have contacted TCS and they suggested turning BEMF off, and that does not help. Turning to 128 speed steps does not produce slower starts or speeds, nor tweaking CV 2 5 or 6.

 

Having the same issue here. Can't adjust enough to fix it.


Sent from my iPad using Tapatalk

 

Here's a copy of what I just posted at The Railwire about this problem. It has nothing to do with the speed table or CV's 2, 5 and 6.

I got tired of waiting for my TCS "drop in" decoder, so I decided to hard-wire an ESU LokPilot (no sound) in my FEF. The LokPilot is small enough that it fit under the rear of the stock Kato board, and I used the traces on that board as solder points for the power pickup, motor leads and front LED. So far so good.

But when I started running the loco, I had the same problems you did. Speed step 1 wasn't slow enough for me and the engine ran very "jerkily" (is that a word?) until I got up to about 5 on my Digitrax DT400 throttle - then it smoothed out OK. Thinking that maybe it just needed a little break-in time, I let it run around the layout for about an hour, then coupled it up to a 30-car freight. Not only did I have the same problems at speed step 1, but with the load of the freight cars, the engine now "surged" at low-medium speeds and upward. I was not happy.

Then I remembered that this model apparently uses a new coreless motor, and began to wonder if I needed to adjust the BEMF parameters in the LokPilot for this motor. The ESU has 4 such parameters, which I won't go into here, but it turns out that three of the four parameters needed some major manual adjustment to get smooth "creep" at speed step 1, and to avoid the surging. After about 30 minutes of trial-and-error programming of these four parameters, the engine now runs like a dream - creeping at step 1, smooth as butter in the rest of the throttle range.

Now here's the problem - unlike ESU's LokPilot (or Lenz's Gold/Silver series), it doesn't appear that TCS has user-adjustable BEMF parameters. I just downloaded their general programming manual, and I don't see any CV's for BEMF parameter adjustment.

So here's my conclusion.

1. The problems we are experiencing are related to the BEMF implementation.
2. If the individual BEMF parameters are adjustable, like on my ESU LokPilot, you can smooth everything out and get tremendous performance from this engine.
3. The TCS decoders do not appear to have individually-adjustable BEMF parameters.
4. If I'm right about 3, you're basically screwed, unless you are willing to do what I did, which is buy an ESU LokPilot decoder (or a Lenz Gold/Silver mini, or some other decoder that has adjustable BEMF parameters) and hard-wire it into the standard circuit board. If you want to do this, I can lead you through the steps (which require cutting some traces on the board, scraping some insulation here and there for solder points, and so forth). It's a couple of hours of work and needs some modest soldering skills, but this will solve your problem.

Note, finally, that I'm not an expert on TCS decoders, and it may be that I'm missing how to adjust individual BEMF parameters for these decoders. Perhaps someone more familiar with TCS's BEMF implementation can chime in.

John C.

 

UPDATE:

Someone on The Railwire suggested turning off BEMF on the TCS, and instead using the "dither" control. "Dither" on a TCS board is adjustable with CV's 56 and 57. You turn off BEMF by entering the value of "0" in CV61; that automatically turns on "dither" and you can adjust the dither using CV's 56 and 57. More info here:

http://www.tcsdcc.com/BEMF.pdf

John C.

 

Thanks, Rick. I corrected my earlier post to indicate that a value of zero in CV61 turns off BEMF in the TCS decoder.

Will look for your results using dither.

John C.

 

Sorry to see these issues with TCS. Perhaps there is some idiosyncrasies with the coreless motor?

I am awaiting my ESU decoder to install. If it has issues, I have a Zimo decoder I can try as well.

 

Here is what I posted on the RW

If you set CV61 to "0" on a TCS decoder, you are actually shutting BEMF and are toggling over to Dither Control. As JD said, there is no adjustment for BEMF on a TCS decoder, it is automatic.

To help slow things down you might want to try adjusting CV56 & CV57. This is explained in this link It's from TCS's page and explains how Dither works.

http://www.tcsdcc.com/Customer_Content/Technical_Info/Tech_Info/FAQPage.php?q=21

This is also from TCS's site and and shows a little more how to adjust the Dither Control

http://www.tcsdcc.com/BEMF.pdf

I had a similar problem with a TCS chip I installed an Atlas VO-1000. The closest thing I could figure out was that the chip had both the BEMF and the Dither on at the same time, basically the chip was scrambled and I was told by DCESharkman to do a factory reset and then I adjusted the dither. The unit runs like glass at low speed now.

It takes a little playing with until you get use to how the values work and how they react. Not sure if this will help, but it 's always good to know how to set the CV's


Added:
Now one NOTE, this is what I did on the VO-1000 chip, but I would think the chip for the FEF would have the same settings.

CV61=0 BEMF is OFF.

When CV57 has a value of 0, Dither is disabled. When CV57 has a value greater then zero it is active.

​

So I think what was happening on mine is CV61 was set to 1 or higher [default] and CV57 also had a value of 1 or higher, so both the BEMF and Dither was on at the same time. This caused the loco to run very speratically. It would start out running smooth but if I increased the speed it would jump up at a very odd rate of speed and would surge, the same thing when I slowed it down. If I tried to keep it creeping it would do OK, but not as slow as I can get it running now.
One would think that if CV61 is set to a value of 1 or higher so that BEMF is on, it would cancel out CV56 & CV57 so they had no effect.

 

I'm sure it is an issue with the interaction between BEMF implementation and Kato's new motor. I've never had a problem with the ESU's motor control before this - it has been absolutely flawless in whatever installation I did. But this one had issues - correctable with fine-tuning of the BEMF parameters, which I've never, ever touched before. So this new motor is presenting some BEMF challenges. I haven't tried just turning BEMF off completely to see what happens with the ESU LokPilot, but I might experiment with that just for reference purposes. It may end up being the same with the TCS - it might perform better with BEMF turned off. I hope some of you with the TCS decoder will try it and report back.

John C.

 

Digitrax decoders with BEMF have the same problem. You must adjust CV 61 to 0 and then adjust CV 56 and CV 57 to get the desired very slow speed effect.



Shades

 

I had a real stinker of a time getting the BEMF set for the coreless motor. Still working on some very find tuning.
I had trouble with the loco jerking under load at higher speeds. If I got it running good at speed step 1, then it would surge at higher speeds. Looks like I have it running good for now. Maybe some hours of running will help. But I really don't think there is any thing that will wear or break in so to say.

 

What decoder are you using, and what things did you change? Maybe we can build a sort of database for what works . . .

John C.

 

John,
I am using a sound decoder. The LokSound Micro Select. Got another thread going on about that here too.

Any way I have set the BEMF as follows: CV 53=125, 52=5, 51=0, 54=50,55=100 and 56=255

 

Interesting. I'm using very similar settings in the ESU LokPilot, which has the same motor control circuitry as the LokSound.
CV 52 = 6
CV 53 = 120
CV 54 = 60
CV 55 = 120
CV 56 = 120

The only major difference is CV56, which is the BEMF "strength" or "cutoff" control, and I found that reducing this to about half reduced the surging at higher speeds with a significant load (30 freight cars) on the engine. You might try that and see if you notice any improvement.

I'm going to order a Zimo MX621 to try out with this engine. I've never used Zimo decoders before, but their motor control is legendary, and they seem to have made coreless motors their specialty.

And I'd note for anyone that wants to go the hard-wired route, you can order the basic DC circuit board from Kato for $5. You'll need this board if you are going to hard-wire to provide power pickup and solder points for the decoder.

John C.

PS - what sound file are you using with the LokSound? I haven't been too impressed with ESU's files for standard two-cylinder locos, although the BigBoy file that I've used in my Challenger is excellent. But that file won't work with the FEF since it is set up for a 4-cylinder articulated.

 

I agree with you John. On the install that I did ( LokSound Micro Select) I modified the light board much like you stated.
I left the motor clips soldered to the motor. I cut the traces so the motor clip pads were isolated then soldered two wires to each pad to run to the tender. I cut traces on the board and used a 1K resistor for the power to the light from the right rail. Soldered the two pick up wires and one wire for the H/L control. I ran the 5 wires under the light board to the tender on top of the draw bar. On the tender I did not cut the weight nor drill any holes in the floor. I mounted two 10X15X8 sugar cube speakers with enclosures on each end of the floor. Then I mounted the decoder to the weight with double sided tape. Made all connections to the decoder in the tender.

Matt at ESU Had me do beta test for a new sound file for the 844.

 

Hi Folks.

Here's a video of what I've been able to accomplish on the slow-speed front using an ESU LokPilot (no sound; the LokSound's motor control circuits are identical). I started at speed step 1, and ran it up to about 15 (out of 128):

[video=youtube_share;P2n4AIq7HiU]http://youtu.be/P2n4AIq7HiU[/video]

John C.

 

Wow. Would very much like to hear/see this. Photos? Video? Do you know when the file will be generally available? I might go this route for sound . . .

John

 

When you turn Bemf compensation on, it IS supposed to disable dither, and from what I've seen I believe it does, but TCS's "auto-adjusting" bemf compensation does have issues with some motors. Also, I think it is important to note that setting CV61 higher than 1 does not necessarily turn on bemf, CV61 has to be odd to enable bemf (i.e. 2, 4, 6... would turn bemf off).

Looking at your speed table, I noticed that you are not using it to significantly slow down the engine's speed curve. I wonder how many people that are having the surging issue are trying to slow the engine's speed curve. I have two TCS decoders and on both locos that I have them on, if I enable bemf compensation and try to slow them down significantly, I get uneven speed steps and surging in the lower speed settings.