DH123 Decoder in Athearn RTR


M

midrange

Steam & Diesel Fan
I bought a Athearn RTR SD40-2 and installed a DH123 Decoder in it.

I put it on the tracks, and was not impressed with the performance. (i'm new to DCC) It takes almost half my throttle to get it moving (Zephyr Xtra), and the motor hums loud from Stop - to between 2-3. Once i get to almost 3, it starts moving.

So I was told to edit and change the CV's. SOmething about speed steps, Voltage etc etc.

I was sugested to change to these settings. CV2 = 20. CV3 = 40, CV4 = 40, CV5 = 125, CV6 = 80, CV54 = 0, CV55 = 128, CV56 = 80, CV57 = 6, CV65 = 1.

Well I tried that, and the trainran even worse and I don't want to tell the guy helping me as he has beentrying hard to make my train run better.

With those settings, the train ran way slower, took forever to get it moving.. still took half my throttle to get it moving, and switching from forward to reverse, even the light was delayed changing.

So Does anyone have any suggestions what my CV's should be set at?

Thanks
Brian
 
As my buddy Clyde on the old WP(american crane operator) once told the fella that was perstering him to run the crane: go on get up in there,,,now ya see those two levers there,fella says ya, Well the one on your left is lever A -go on pull it back --see how that works-fella says yeah ,boy that's somethin. Clyde tellsthe man now see lever B,,yeah says the fella,,,Good says Clyde get down out of that thing and lever her B...Guess the cv's are kinda like them levers............leave em b. I've adjusted cv 2 with the old power cab set er to 1 in the program mode if it mves real fast adjust er down or no movement adjust er up . IF fine adjustment is needed for 3 and four then proceed.
 
midrange said:
...I was sugested to change to these settings. CV2 = 20. CV3 = 40, CV4 = 40, CV5 = 125, CV6 = 80, CV54 = 0, CV55 = 128, CV56 = 80, CV57 = 6, CV65 = 1.
Click to expand...

Hmmmm....... My 02c, FWIW, YMMV etc etc.......

I think you're changing *way* too much stuff here. In addition those settings for CV2, 5 and 6 are gonna mess with you (we'll get back to the others);

CV02; V start
CV06; V mid
CV05; V max

[Yes, it goes 2,6,5!] - They can all be set between 0 (default) and 255 and define the different voltages at different throttle settings. CV05 for example is set to 125 = ~50% top speed. You've also changed acceleration & deceleration rates which will indeed make things seem "sluggish" to respond - Valid values are 0 (default) thru 31decimal - So at 20, things are gonna take *forever*......

Here's what I'd do;

- Factory reset. [Set CV08=8]
- Now we want to get 'er moving at speed step 1 - A couple of ideas;
- Set Vstart CV02 = 10 ; Try that [Be careful - she may take off like a jet if this is set too high.....]
- Set a "kick start" [CV65 =1]; Try that.

If she's still not moving, increase CV02 to, say, 40 and repeat.

Once she gets going we can mess with some of the other stuff.

Hopefully the above will get it moving and running close to what you expect - We can dial in inertia, mess with speed tables and so on later.

Got JMRI?

Good luck,
Cheers,
Ian
 
Last edited by a moderator:
Try NCE. I do not like digitrax decoders, I prefer NCE. You should be able to get one that will plug into the same plug as the digitrax.

Otherwise, I recommend resetting the decoder and changing one variable at a time until you get it to run properly.
 
There is NO DIFFERENCE in performance regardless of decoder brands! You will need to make the following adjustments regardless of what brand your decoder is.

Reset the decoder (CV 8 to 8 for Digitrax, or CV 30 to 2 for NCE) then program the address in again.

ONLY change CV 2 to get it to start crawling when you move the throttle a little bit. In my experience, Athearn motors need a value between 40 and 50, or slightly higher if the engine is old/frequently used. Start low and work your way up!

The engine hums because the motor is receiving power, but not enough power to get it to start turning and so the energy is being released as sound and heat. Once you get your start speed up to the point where the engine starts moving at speed step 1, the hum should quiet down if not disappear.

Changing the speed tables, mid and high speeds are only necessary if you're trying to match different locomotives/brands (which is usually unnecessary) or trying to set a max speed.
 
I have to respectfully disagree to that. I have seen the same locomotive run differently with different brands of decoder. In my experience, I like the way my locomotives run (smoother) with NCE vs. Digitrax.
 
Ok, if you say so.

I've tried NCE and Digitrax decoders and I've found them both to be the same as far as motor control except that Digitrax is stuck in the stone age and doesn't have an LED compensation mode for the lighting functions, but if you don't need any flashing lights, Digitrax decoders are less expensive.

What I have found with both brands is that they're both stuck in the stone age in the fact that their ditch light logic is hard coded into F0 so that if you program ditch lights, they cannot be turned on independently of F0.

NCE is the best brand if you want realistic flashing LED ditch lights. TCS is a close second, but flashes sightly too fast at the lowest speed setting. Get Digitrax if you want to be disappointed :D (been there, done that!)

Oh, and if Lenz is still selling decoders, don't get them. They don't like to speed match with other brands even with manual adjustment of the speed curve. (been there and done that too!). Lenz also makes decoders for Atlas (non-sound), and Bachmann (non-sound).
 
thaddeusthudpucker said:
I have to respectfully disagree to that. I have seen the same locomotive run differently with different brands of decoder. In my experience, I like the way my locomotives run (smoother) with NCE vs. Digitrax.
Click to expand...

i have to respectfully disagree. i seen same exact car driven differently by different drivers, so? locomotives differ and decoder configurations differ. if you configure it right digitrax will be as smooth as nce. on other hand you can configure enough kick into nce and it will run all jagged. both decoders are silent and both equipped with all the modern PID technology (actually, does NCE have BEMF?).
so your advice to the OP's to solve the problem by replacing decoder is just not right.



OP there was no need to touch all those CVs at once. you don't start randomly turning options on and off when your TV is not loud enough do you? so, start by resetting the decoder to factory settings as suggested above. in a nutshell (again , as explained above) you want to bring your CV2 up just enough to get the train moving on step 1. in case you have significant stickiness in your loco, you will want to compensate for it with kick rate and ammount. stickiness is when your locomotive moves at speed 1 if it is already moving, but will not start moving if standing still. unless i find step by step guide on speed configuration already posted here before i get home, i will post the article from JMRI help document on this.

and as far as efforts of person who suggested you the fix, it is almost as if you had a doctor diagnose you over the phone. he might be not professional enough to do that. but you have enough common sense to realize that troubles such as this one can not be resolved remotely.
 
Nope, NCE does not have BEMF, the SR in the decoder designation stands for "silent running" Seeing how almost all of the NCE decoders have SR in their designation, it's safe to say that NONE of them have BEMF.

Digitrax decoders have Scalable Speed Stabilization which is their fancy word for BEMF with the exception of the economy decoders such as the DH123.

I do not use BEMF so it's of no concern to me.
 
You know, the OP didn't ask anybody's opinion of his choice of decoder , he asked for help with what he had. The way this thread has gone so far looks like what I see on car forums when somebody asks what tires he should put on his Ford, inevitably somebody will tell him to junk the Ford and buy a Chevy.
To the OP, reset the decoder you have by setting cv8 to 8, and don't change any other settings except cv2. Start at 10, and work your way up until the locomotive starts to move at speed step 1. After that you can fiddle with other settings such as address and momentum.
 
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