New motor and sound decoder in Athearn challenger

[propmeup1]

question. I'm thinking about replacing the motor in a used challenger I picked up a year ago. It never ran properly.  Anyone have a suggestion on what kind of motor to use. I have two challengers both with the same problem.                    I also am changing the sound decoder out.  No big deal with that, it's the motor I need advice on please.
       i purchased it privately and got screwed.  I even called him back to let him know. He did pick up. i told him he knew going into this deal he was screwing me. He did not seem to care and because it wasn't done on ebay and I can really do nothing about it.   Time to move on and rebuild it. I did tell him he is going on the bad trader alert. He did seem to care about that either.
   

[peteski]

I have not had any problems with my Athearn Big Boy and Challenger motors, nor I recall having heard anybody else having problems.

What specifically is the problem with the motor? Are you sure the motor is the culprit?  If the motor is really defective, why not replace it with the factory original motor, and save any hassles of retrofitting another motor?

If this thread is mainly about the motor, it would be better fit in the N/Z section rather than in DCC section.

[Mike C]

    So what is the problem with the Loco ? Does the motor run at all ?


    OOPS 1 min late LOL

[propmeup1]

Both challengers will run and stall, run and stall. The latest one i got a year ago is worst of the two. It hardly moves and the sound is dead.  I was told on the site probably two years ago that it's inside the motor. to clean the brushes and armeture ect.  I've done that but it still runs the same. The last One i got is worst.  Yu are most likely correct about the motor.  I did remove it and it seemed to be fine.

Athearn said it's probably the decoder, MRC in both and both big boys. Big boys run fine but i can't stand the MRC sound, well the whistles at least.

So you would probably recommend replacing the decoders.  Ok.

[Mike C]

   Try a cheep non sound decoder first .  If that cures the problem then do the sound . I bet that a keep alive would fit too .      Mike

[propmeup1]

Yeah for sure. i'm doing the speakers over too.

[NDave]

My 2017 issue challenger wore thru its brushes in <1 year, and the accumulated graphite dust caused internal shorts in the commutator. I replaced it with a factory motor from Athearn about 2 years ago, and replaced the 1st gen Tsunami decoder with a Tsunami 2 Steam 2 decoder shortly thereafter. It has been running great for the last two years. I posted separate threads with pics for the motor swap (Dec 2019) and decoder install (Mar 2020) on nscale.net (I was previously asked not to post links to other MRR websites on RailWire, but I use the same screen name on both sites, so you should be able to find them. message me if you can't).

At the time, I seriously considered trying to install a coreless motor from Tramfabriek in the UK (https://tramfabriek.nl/motors.html). They sell an number of motor sizes with adaptors ("motor casings") and shaft adaptors. Altho' it would not be a drop in, I thought that I would be able to modify something to fit. That project is still on my radar as something to try... the open frame motor Athearn used is a current hog, and doesn't respond as well to the "dynamic digital exhaust" of the Tsunami decoder as the coreless motors in my other steamers.

Good luck!

[peteski]

Both challengers will run and stall, run and stall. The latest one i got a year ago is worst of the two. It hardly moves and the sound is dead.  I was told on the site probably two years ago that it's inside the motor. to clean the brushes and armeture ect.  I've done that but it still runs the same. The last One i got is worst.  Yu are most likely correct about the motor.  I did remove it and it seemed to be fine.

Exactly, in the scenarios you described, motor is likely the least of your worries. Yes if the commutator segment gaps fill up with oily graphite or carbon brush dust, that can cause poor performance, but more likely problems are elsewhere in the loco. For example the decoder can be faulty, or  the drive train can be binding.  DC electric motors are very simple (and robust) devices - not much can go wrong in them. But if if a binding drive train creates heavy load on the motor (while it is running for extended time), that can burn the motor out. But it is not the motor that was at fault.

Of course a faultily decoder can make the motor appear faulty.

It would make sense to actually perform some basic troubleshooting to pinpoint the cause of the problem.  I would remove worms from both engines and see if the drivers move freely.  If they are ok, reinstall the worms and take the decoder out of the equation. Run the loco using DC. And I don't mean run the decoder in DC mode - electrically disconnect the motor from the decoder and temporarily wire it to the track pickups.

That should give you some more insight as to what the problem is.

[woodone]

The key words here are MRC decoder. I have over the years replaced the MRC sound decoders with something different, which was much better. The speaker and enclosure in these seemed to be OK. I sure would do has Mike C said -try a non-sound decoder before looking at changing the motor.- Or has Peteski said, try running on DC -with no decoder.

[jdcolombo]

If you're going to change the decoder anyway, try that FIRST.  Add a keep alive (A TCS KA-1 will fit easily in the tender along with either an ESU LokSound micro or a Tsunami 2 1100.  For a speaker, use a 13x18 cell-phone type in an enclosure that is at least 8mm deep (with a 1mm bottom, 9mm overall).  You've got enough room in that tender for an aircraft carrier, so use it.

If the decoder swap doesn't cure your problem, then look elsewhere.  But my money is on the overall electrical pickup (cured by the keep-alive) and the decoder itself (cured by a new one) being the problems.

John C.

[peteski]

If the decoder swap doesn't cure your problem, then look elsewhere.  But my money is on the overall electrical pickup (cured by the keep-alive) and the decoder itself (cured by a new one) being the problems.

John C.

That is why it really makes sense, before swapping the electronics, to make sure the model is otherwise mechanically and electrically reliable (running on DC with decoder bypassed or not installed).

[NDave]

Perhaps I should share the symptoms my 2017-release challenger exhibited, and how I narrowed the problem down to motor failure...

My challenger was a bit of a problem from the start, with 3 trips back to Athearn in it's first 15 months or so (spending more than 9 of its first 15 months at Athearn):
First, nearly all of the axles, loco and tender, were out of gauge on the narrow side... causing it to derail or mechanically hang up in many of the turnouts on my layout. That was trip #1 back to Athearn (in retrospect, I could have re-gauged the wheels myself... but I was just getting back into N scale after 40 years, and didn't want to screw up such a complicated loco). Next, the sound output of the decoder died... loco ran, just completely silently. That was trip #2 back to Athearn. Then, the front gearbox froze. That was trip #3 back to Athearn, and it ended up going all the way back to China for "refurbishment."

So when the loco started running erratically again just 6 months after I got it back from its third service trip,  there was no way I was sending it back a fourth time. This time, the loco might run for a while, but as it "warmed up" it would start slowing erratically, even coming to a stuttering stop. My NCE Powercab has a setting that allows the controller to display the current draw, and as the loco started behaving erratically and "stalled"  the current draw would shoot way up... even exceeding the stall current of the motor. This was the first indication to me that the issue was NOT a bind in the running gear...

So I proceeded to remove the motor (first removing the shell, then disconnecting the light PCB to access the motor). Once the motor was exposed, I could see that it and the cavity it sits in were coated thick layer with fine brown-red powder, and the powder was all over inside the open frame motor as well. I concluded that the powder was worn from the brushes, and that it had accumulated in/on the commutator and was causing the motor to short out while running (causing the massive current draw). After pulling the motor out, I connected it to a straight DC powerpack, and it exhibited the same sort of erratic behavior as it did in the loco. I also connected a 40 year old motor from an old N-scale Atlas loco I had in my parts box to the decoder... and it seemed to be controlled just fine by the decoder.

I pulled the brushes, and cleaned up the commutator with a Q-tip and alcohol, but the brushes were worn down to nubs. Athearn did not stock replacement brushes for the motor, but did have "replacement" motors in stock... the factory motor in the 2017 release was a 5 pole, what they had were 3-pole motors from the earlier release. But the replacement motor ended up fitting and functioning just fine, once it was all back together. It's been running great for nearly two years now.

I was able to scavenge some brushes to fit the old motor... and after cleaning it up it seems to run OK now, so I have it in my parts box as a backup. But, if the currently installed motor does fail, I might try to retrofit the loco with a coreless motor: the open-frame motor  is REALLY noisy and a major current hog compared to the coreless motors in all my other steamers. I also think a coreless motor will work better with the dynamic digital exhaust of the Tsunami 2 decoder I have installed.

[peteski]

Yes, I have seen brush dust mixed with oil very negatively affect the motor (since that "goop" is conductive, it will provide low-resistance (but not zero ohm short) between the commutator segments, draining the current away from the windings.

I have not had to examine my Big Boy or Challenger motors yet, but I wonder if those are typical "Kato clone" motors and they use standard size brushes, so any brand brush would fit (like a Kato)? It is possible that the Athearn brushes are very soft, wear out quickly, turning into dust?

[NDave]

Old motor on top (after it was cleaned up), replacement on the bottom:

[peteski]

Thanks!
These are like motors used in Walthers/Life-Like Mallets. Not the standard Kato/Atlas motors.

Not to long ago I have serviced a Mallet and the Commutator was also causing shorts, which then caused the brush spring to get so hot that it lost its temper. It compressed and no longer applied pressure to the brush causing the motor to be very intermittent.    But I don't recall whether the brushes were same dimensions as the Kato/Atlas motors.