Is this a TCS Decoder Anomoly?

Hello,

Well in my other post I was asking about the momentum settings on the TCS decoders. I found out the answer there, but now something strange is happening.

I did not do all of the extended momentum becasue I just didn't see a real need on a yard switcher like this Altas RSD 4/5 unit with the older non-scale speed motor.

It has the TCS CN installed and programmed similar to the way I have programmed every other locomotive.

CV3 = 6
CV4 = 6

Using BEMF set to 110

Speed table step 1 = 4 and step 28 = 139 using the log curve in Decoder Pro.

Here is the issue, as I increase the throttle to say 25% the loco starts out slow and smooth. But as I increase it to 30% it suddenly takes off like a spooked jackrabbit and does not settle down until I drop the speed to below 30% throttle. I should say that does not go all the way to max speed, but it isn't too far off that.

I do not try to run the locomotives very fast, I like more prototypical scale speeds. But it seems to just jump from smooth to rocketship in the difference of a 1% throttle change from 29% to 30%.

So does this sound like I need to reset the decoder, or do I have a suspect decoder?

Thanks!

 

I have seen this problem also while using the linear curve. My heavy-handed work around was to stop using the speed table and use the start, mid and max volts CVs, thinking someday I will revisit the issue.

Except for this anomaly I like the TCS decoders.

 

I had the same issue with both a CN and a CN-GP. I gave up to.

 

Interesting thread but leaves me wondering about the best, current, up-to-date DCC decoder theory/practice book. I've learned that there are many CVs that combine to set the actual speed program vs. throttle setting. For example, there's the lo-mid-hi speed setting, speed tables, acc/decel trimmers and whatever else.

So far, I only do a decoder reset and then bang the lo-mid-hi CVs until things look better ... not best results at all ... MUs are matched only in a narrow speed range ...

So how about it, what's the best current reference book? I use digitrax, TCS, Lenz, and have one unknown decoder ...

I'm looking for one simple method that works for all. Would like to match all locos, whether MU'd or not. Would like to treat the throttle on my DigiZephr the same for all locos ...

 

I have had similar results trying to use the 28 step speed table with TCS decoders when BEMF compensation is enabled. Unfortunately, I also have not had good results using Vmid and Vmax, I get uneven speed changes between steps, sometimes even having the engine slow down when I increase the throttle one step. One thing I have not tried yet is to modify the 28 step table, making it non linear, to see if I can get rid of the sudden jump in speed.

There seems to be something not quite right with the Bemf logic on TCS decoders when you try to slow the speed range down, at least on some of them, and it seems to affect different motors differently. There was a rather lengthy discussion about it on the NCE-DCC yahoo group back in January(if your a member there you can find it by searching for "TCS BEMF"). There was also some discussion about it on the TCS-decoders group at the same time.

 

I just turned everything off and reset the speed table curve. Now it jackrabbits at a throttle setting of about 65%. That is not an issue anymore because I do not use the yard switcher on anything higher than about 45%

No more TCS decoders for me.

 

TCS Anomoly

Just curious on your issue with the TCS decoders. I don't understand one half of what you said was the problem. And by the way I am not in any way arguing with what you said, you obviously have a far greater grasp of these issues than I have. But what I do understand is that you are not going to use TCS decoders any more. Have you, or have you any plans to, talk to TCS so that they could be better prepared to serve your (our) needs in the future?

Old Fat Robert

 

Had the same issue with all 5 of the 5 TCS CN-GP decoders I purchased.
When I contacted TCS they were real nice and helpful — in the beginning. Then, when they couldn’t solve the problem, they treated me like I was some sort of imbecile that didn’’t know how to install a measly decoder and told me to find someone who could.

Try turning off/disabling the BEMF and see what happens.

 

Thank you for the above information on TCS, I am about to buy my first decoders. That company is now off my short list of manufactures.

 

Except for this speed anomaly I like the TCS decoders. They have longer acceleration/deceleration times than my Digitrax decoders. I set the Digitrax decoders to the maximum value 32 and the accel/decel time is not long enough.

 

Keep this last point in mind David in terms of decoder programming conflicts created by user CV settings. In plain English it is possible to have "contradictory decoder settings". What we see as unexplained is perfectly logical at the programming level. As an example I have found BEMF logic override certain CV settings and be overridden by certain CV settings. That is just the tip of the iceberg.

My definition of a decoder is: Pandora's Box. Don’t expect too much from any manufacturer with these types of issues. IMO TCS produces as good a decoder as the rest of the manufacturers. With that said, I tend to follow a KISS approach when setting CV's.

Jerry

 

I understand what you are saying, but that is not the case here. There is simply a bug in the Bemf logic in at least some of the TCS decoders. You absolutely should be able to use CV5 and CV6 or a 28 step speed table to adjust the speed curve AND have Bemf enabled, but these combinations don't work quite right with these decoders.

 

I agree with you entirely, it should work and there is a logic problem at the programming chip level with these decoders. Hopefully it will be addressed by TCS, however until such time that it is resolved we have arrived back at my point.

Jerry

 

Count me as another with the same problem with these decoders. I was able to use Vstart, mid, max. I'm not too picky about my speed matching, but this was still disappointing.

 

Like I meant to say earlier, mine performed considerably better when I turned off (disabled) BEMF. You guys might give it a try. You can always turn it back on if it doesn’t help.

 

The TCS decoders I have do not exhibit the odd behavior when Bemf is disabled; however, I have some locos that really benefit from bemf so disabling it is not an acceptable answer.

 

i recently bought 20 brand new tcs cn-gp decoders. they all work such as turning on the light and spinning the motor at full throttle.

NONE of the 20 decoders could be read or programmed with decoder pro !!

guess this is a DOA rate of 100%.


of course i sent an email to tcs describing exactly what happened. guess what. they don't even think of replying !


no more tcs decoders for me.....

 

All of my correspondence with them was by email also. I bet they wouldn’t care for me posting the text anywhere.

Probably why they haven’t responded to you. They don’t seem to have the ability to ever be wrong, so its in their better interest to say nothing.

Rick

 

I had the same problem CSX Robert had where the loco, running at a slow speed, would actually slow down when I moved to the next higher speed step. I called TCS and they told me that the decoder did not behave well with the top speed set too low. Mine is because all my locomotives are computer controlled and top speed needs to be around 45 MPH or so for the computer software to move the loco in a very smooth manner.

TCS told me there was no fix to this problem except to jack up the top speed. No more TCS for me either. ....Tom