Old Athearn Challenger Ran Funny on DCC but OK on DC

[conrad]

Happy 4th to all.

As a part of breaking in my new DCC-EX Programmer I took out my Challenger for a run.  It was very slow on DCC, even at max throttle.  Read all the CV’s no change.  Ran it on DC and it ran properly.  Back to DCC and it ran properly.  A mystery to be solved??

Start Voltage CV2 = 0 as I’m using the speed table with a linear run from CV67 = 9 to CV94 = 255.

Forward and reverse trims are set at CV66/95 = 128.

Accel/Decel CV3/4 = 20    BEMF Cutout CV10 = 0

Motor parameters are:

Kp = 25, Ki = 20, Intensity = 128, Sample Period = 15, and Sample Aperture Time = 15

All the DCC running takes place on my Digitrax DB150 “command station” with JMRI DecoderPro and Engine Driver.  DC running was with a Bachmann Magnum transformer (10va).  AND programming is done on my new DCC-EX system – Arduino UNO, Arduino Motor Shield, DecoderPro on Windows 11.  I must note the CV reading is a lot faster with DCC-EX than my old DCC++ or Digitrax PR3 Systems.

Here’s some history of this beautiful looking and running loco:

My 2009 Athearn Challenger with a MRC OEM sound decoder lasted until until 2017 when the decoder caught fire and melted part of the tender and some connector pins.  I replaced the tender and connector and installed a Tsunami TSU-4664N Challenger decoder.  Somewhere in time the headlight died and recently the rear light died also. 

Notes from DecoderPro:

1/28/09: purchased ($300).  original mrc decoder fried 2017.

12/12/17: new tsunami decoder, now seems to work.  start voltage (CV=2) set
                 to 5. no more decoder lockup.  headlight still dead.

10/21/19: CV's 213&214 reduced from 15 to 2.  Slower speed.

3/29/24: set accel/decel to 20, no challenger or big boy whistle.

4/6/24: master reset, loco still slow, lost rear light but have short whistle.

7/2/24: long whistle working. slow speed cured by running on DC then DCC

7/3/24: set cv's, both challenger and big boy whistles working.

Ps: Too bad I’m old (80) or I would try u18b’s fabulous thread “Athearn Challenger (1st Run) Disasembly guide (& bulb replacement) Big Boy too?”  and get those lights working.  Wait, wait, maybe a younger member of my LINtrak club will do it!

Conrad

[conrad]

No nibbles on my two week old post but here’s an update to “funny running” on DCC-EX.

Seems I experienced a similar problem with my HobbyTrain Vectron AlpPiercer (Zimo decoder).  Check out my post on ZIMO-DCC@groups.io for the gory details.  The threat is titled “MX658N18 Decoder Not Working with DCC-EX”.

In a nutshell the Vectron overloaded both of my new DCC-EX systems until, apparently, I ran the motor (w/o decoder) on my legacy Bachmann Magnum DC transformer.  Then after reassembly, DCC-EX worked perfectly.

So, two different locos with different decoders (Tsunami & ZIMO), same DC “fix” (Bachmann DC) and with the same DCC system (DCC-EX) they run.

Is this a mystery of life or am I missing something here?

Conrad

[peteski]

I would blame it on what seems to be "moody" DCC-EX.    I assume they also run ok when on straight Digitrax DCC.

I didn't respond earlier because DecoderPro is not my thing.

PS. I did see your post on the Zimo group.io.

EDIT:  like Sumner I was going to suggest getting some support from DCC-EX end.

[Sumner]

How much current are the two locos drawing.  DCC-EX running with out changing any paramters will trip the current at about 1.8-2 amps.  I can't imagine they could be drawing that much but worth a look.  I haven't had anything similar happen with my DCC-EX command station or hear of something similar from anyone else.

If you haven't I post the problem on the DCC-EX Discord's site....

https://discord.com/invite/PuPnNMp8Qf

... where most of the developers are.  There is usually someone there almost 24-7 as the guys are from all around the globe.  Post under the 'support-and-issues' section or 'new-user-help-and- information.

I run my test track on the output from the DCC-EX command station.  That same DCC signal goes to the main layout and goes to boosters for different power districts there.  I've heard of guys running 6-8 N scale locos off just the command station power and now if you want it they have a motor shield that can go on the command station build for I think under $50 that puts out 5 amps from the command station.

Sumner

[conrad]

Peteski:

When you say "moody DCC-EX" are you speaking about my experience or have you heard other similar stories?
The locos did run on Digi DCC and DCC++ prior to my "upgrade".  I'll set up the Digi again and check.

Sumner:

As I've stated on ZIMO-DCC@groups.io DCC-EX appears to be sketchy to say the least.  See the Swiss guys IoTT YouTube videos for his take on the situation.  However these are n scale locos and draw in the low ma range.  As I remember, the original DCC++ also had a current monitor that seemed to be stable.  What I remember is maybe 250ma max at that time for various locos and that system never exhibited a short. 

As for DCC-EX customer support I did an email ticket and received an email from Fred Decker of DCC-EX.  His take is to adjust the trip settings of the current monitor.  This assumes that the trip is real.  I have doubts as there was no smoke or sparks or heat damage.  Also, as he states the "The default overcurrent trip protection is set to 1500mA, which is reasonable for the L298P motor shields."  The new systems ran fine with a lot of my other locos and now runs fine with many locos.  Look, they have both run the Bachmann 44 tonner (2 function E-Z Command decoder) and Dash 9W (MRC 1645 sound decoder) plus ESU and Digitrax decoder locos.  I only had two strange occurrences that are now gone.  A mystery.

And Discord.  Unfortunately I just can't my head around Discord.  I am signed up but stymied by all the screens.  Both DCC-EX web site and Fred Decker have sent me detailed instructions but I still get lost.  I will plug on but the heat wave here in NYC is somewhat frying my brain.

As I write this I see a flaw in my logic:  I have two DCC-EX system and they both responded in the same way.
Thus something must be up with the locos, MAYBE.

Right how I'm sticking with Peteski's technical analysis "Moody DCC-EX".  Sometimes you fiddle with things and, wow, they start working.

Conrad

[peteski]

Peteski:

When you say "moody DCC-EX" are you speaking about my experience or have you heard other similar stories?
The locos did run on Digi DCC and DCC++ prior to my "upgrade".  I'll set up the Digi again and check.

Conrad,
I have no experience with DCC-EX (either personal, or by reading about other's experiences with it). There was some discussions about it on TRW, but that was more like description of its price and features than actual operating experience.

My "analysis" was strictly based on your problem description, and my experience as a troubleshooter of computer hardware and software (both as a profession and hobby).  In the 40+ years of dealing with electronics I have seen my share or unrepeatable, weird, unexplained or intermittent problems. Nothing really surprises me.