Atlas DC MP15DC Died

[tehachapifan]

OK, hasn't been the greatest couple of days with the hobby. Tonight I was running my Atlas MP15DC when is suddenly died, triggering the short protection in the power pack. Took it apart looking for an obvious problem and couldn't find anything, although I cleaned a bunch of oil off some things that connected both frame halves (screw bushings, etc.) in case that was conductive (is LaBelle Light Oil conductive?). I'm usually really good about applying small amounts of oil but I guess I over did it....and the frame bushings and screws are right next to the worm end bushings if that can, indeed, lead to a short. At any rate, it came to life briefly a couple of times until an audible "sizzle" could be heard before it died again. Now it's dead, dead, dead. Any ideas? Sound like the motor itself or the (DC) light board?

I should mention that this unit always had a bit of a hitch in its giddyup when it was cold and I would first start running it....sort of like a partial short that would then subside suddenly...almost like a switch was thrown. If I had it lashed to something else when it did it, they would both have reduced power and a dim  headlight until it cleared and..bam..it was like they shifted gears and the lights came on brighter.

[Ed Kapuscinski]

Did you check the motor brushes?

They're not slugs the way most are, but are little fingers that can wear down in time. If one of them breaks and jams in the commutator, you could very easily see a short.

[Ian MacMillan]

I had this exact thing happen about 4 years.ago to mine and the issue was what Ed explained. The communicator broke off and jammed the motor and f'ed up some other things. A replacement motor fixed the issue.

[peteski]

Sounds like something inside the motor (as other 2 posts have already mentioned).  Besides a broken or worn out brushes, if there is oil on the commutator, it can attract the carbon dust from the brushes. If enough carbon dust accumulates between the commutator segments, it can short them out (but that is quite rare).

As far as hobby oils being conducive - don't worry, they are not. No hobby oils or lubricants that I know of are electrically conductive.  The manufacturers usually tout that the lubricants "improve electrical conductivity". That is a sales pitch. It does not imply that the lubricant is conductive.  They improve conductivity by coating the metal parts with a film of oil which prevents metal oxidation. That results in a more reliable electrical contact between the metal parts.

Electrically conductive lubricants do exist. But those are specialty lubricants. The really good ones use powdered silver, mixed with lubricating substance. Those are quite expensive and not usually used in model trains.

[tehachapifan]

Thanks for the info, guys! Sounds like a new motor is in order. Hope this was just a fluke as that unit didn't have a ton of run time on it. I would hate to think that the brushes might wear down that fast again....if that's what happened.

[peteski]

Thanks for the info, guys! Sounds like a new motor is in order. Hope this was just a fluke as that unit didn't have a ton of run time on it. I would hate to think that the brushes might wear down that fast again....if that's what happened.

Once you get the model fixed, why not do a postmortem on the motor, to see what failed? It is fun to take things apart. 

[reinhardtjh]

Once you get the model fixed, why not do a postmortem on the motor, to see what failed? It is fun to take things apart. 

It's getting them back together again (in running condition) that is the b*tch.   

[peteski]

It's getting them back together again (in running condition) that is the b*tch.   

That is true, but in this case, there will be no need to ever put that motor back together. 

[Teditor]

That is true, but in this case, there will be no need to ever put that motor back together. 

As Peteski says, Post Mortems are not done on Live Things, but the gutteral research can lead to a better understanding of faults in motors.

First thing, pull the motor out and check it out of the frame, spray out with contact cleaner, relube bearings lightly, at this stage you can also check the brushes and/or any visual defects (broken armature wire/s).

Ted (Teditor) Freeman
From the land down under.

[Chris333]

Victor told you there'd be days like these. 

[Ian MacMillan]

It's only an issue if you have extra parts when everything is put back together.

[peteski]

It's only an issue if you have extra parts when everything is put back together.

...or don't have enough, because some fell down into the carpet. 

[mmagliaro]

I have no dog in this hunt except that I am always keenly interested in why motors fail, particularly
ones that use little metal finger brushes.    I agree, pull the motor, spray it out with contact cleaner, particularly
on the commutator, and see if you can get it running again.  If you do go for a replacement motor,
I'd love to see close-up photos of the inside of this one.  If you don't want to do it, mail it to me and I'll take it
apart and post photos.

[primavw]

I agree with what others are saying. If you get some time figure out what went wrong, so the rest of us can do something preventative to our MP15DC's!

[tehachapifan]

I wonder if my power pack might have anything to do with this. I've also lost some light boards in units that were on a track ran by an older (like 20 year old) MRC Tech II 2800 dual cab control. I think I heard somewhere that this pack has a "pulse" feature that may not be good for modern N scale locos. Any knowledge on this? Do all or any newer power packs lack this possibly-damaging "pulse" feature?