Mashima Motor Rot- Wow

[u18b]

I recently acquired a BLI E8A with a Pargon 2 decoder.

Ran badly.  Worked on it a good bit.  Still poorly.

So I pulled the motor.   
It was a common Mashima motor.




Uh-oh... seems scratchy when I turn the motor by hand.

I conclude this motor is probably hosed, so I decide replace it.
I then decide to explore.... so I pull the guts out of it.  You can see that the motor brushes do not have much wear.



By the way Mark @spookshow, you often say on your site.... this is a closed motor so I don't really know what's inside.
Well, in this case, it is a skew wound 5 pole motor.

So far, nothing looks problematic.

But then I look inside the case and I am shocked.
Mind you, I cleaned this up.  I should have taken a photo like I found it.



The magnets are very thin and have a shiny silver surface.  I am thinking they may be plated Neodymium magnets.
Well, whatever they are, it appears the plating is coming off and they are rotting (link Zamac rot).

I've never encountered this before.   It was discouraging.
Thankfully, I had another Mashima motor the same size and I installed it in the loco.

[mmagliaro]

Yes, Mashima motors use Neodymium magnets, and yes, if they aren't protected from the air by a plating, they corrode.  It's not really "zinc rot".  They just oxidize and crumble.  That's a crying shame.  Mashimas are such excellent motors, but  they've been out of production a long time now.  There is little chance of finding a suitable replacement magnet.

[peteski]

I was surprised to find out that Mashima used those super-magnets back in the day (as those motors are likely 10-20 years old).  I always thought they would have standard ceramic magnets used in most non-coreless motors used in N scale models.  This also explains why those are such good motors.  Strong magnetic flux makes them more powerful than motors using ceramic magnets.

The disintegration of the magnetic material is a common problem with those Neodymium super-magnets. For  example I bought some small Neodymium magnet cubes on eBay probably 15 years ago.  They had a gold-color metal which after few years started splitting and peeling back with the Neodymium oxidizing into fuzzy magnetic material.  I guess when the coating is breached the humid ambient air causes the oxidation.



But other similar magnets are much more stable. It likely depends on the coating material's quality and integrity.

Max had some tubular magnets made to replace the rubbery magnets in Con-Cor/Rivarossi "can" motors. Hopefully those magnets are more robust.

[C855B]

Oh, great. Just great. I have four BLI E8s from the first run (2009). If this condition is endemic, which I suspect it is, then we/I need to be looking into replacement motors. Any suggestions?

[mmagliaro]

Neodymium magnets are used a lot by industry.  I can't believe this is a common problem.  I'm sure there are a lot of cheaply-plated magnets out there, but I have never had a Mashima motor fail, for any reason.  I wouldn't panic if I had them in my models (which I do).

[C855B]

Good point, and I hope you're right on this. I haven't run the Es in a while, so need to do that just to see where I stand.

Making me cringe just a little are the three PA/PBs from 2010 I just sold at a train show. They were never run - shelf queens - so I hope I've not made an un-friend if by chance they had the same thing go wrong, 'cause I obviously would have no idea.

That said, Ron may not know what sort of life his E-unit had. If there was water involved in some sort of disaster or accident, cleaning-up everything else is feasible, just not a semi-sealed unit like a can motor.

[delamaize]

This is exactly what happened to my model power 4-4-0. I still have not found a replacement motor. Makes me sad that's one of my favorite locomotives

[spookshow]

I'd be more worried about the Paragon2 decoders than the motors. Half of my old BLI E7s and E8s have died from decoder failure 

-Mark

[brokemoto]

I'd be more worried about the Paragon2 decoders than the motors.

Thank you for the heads-up.  I have a few BLI locomotives.  I use DC, only.  I will be watching out for this.  Add these to the list of alleged "smart" decoders that will not stand up to DC (B-mann).

This is exactly what happened to my model power 4-4-0.

Is this the MP under the Tagers or under MRC?  i have both.  Thank you for the update.

I recently acquired a BLI E8A with a Pargon 2 decoder.

Ran badly.  Worked on it a good bit.  Still poorly.

So I pulled the motor.   
It was a common Mashima motor.

Thank you for the update.  I have several BLI locomotives.  I will be watching out for this.  It is a shame that BLI charges premium prices, has good mechanicals but such poor electricals and uses out of productions hardware.

[randgust]

we all know the pain of zinc pest, and that probably 50% of the original Atlas/Rivarossi frames are subject to it by now.

And now there was a specific 'date range' when MT was most certainly having issues with zinc frames as well....hard to believe but I've had some in my hands now to study as a 'bad batch'.

So to me the next logical question which can be surveyed here is trying to determine if this is a time-dependent across-the-board magnet fail that's only waiting to happen on nearly all of them, or one that's annoyingly batch-dependent, like MT.   And part b will be the time lapse estimates.

I've had a few Mashimas, including some that are in storage I have to check for damage, but that's discouraging as I always considered their motors to be at least B+ grade, if not A.   The two most failure-prone motors I've had to deal with are the round Atlas/Rivarossi 'cans' (gummy magnets), and the original Trix F-unit motors (commutator damage/fire rings from soft brushes).   Those were both 100%, plan on it, fails.   The biggest A+ motors I've seen were the original Sekesui five-poles that were in the PA's, I've repowered several vintage units with those and never had a fail or maintenance needed beyond lubrication.   Same deal with some vintage Sagamis, I put one in my original 1970 Trix F-unit, still going after at least 40 years.  All ceramic magnets as far as I can tell.

[OldEastRR]

I'd be more worried about the Paragon2 decoders than the motors. Half of my old BLI E7s and E8s have died from decoder failure 

-Mark

Are these BLI or PCM E units?

[Jim Costello]

One of my Lifelike/Walthers SW1200's stopped running, the motor jammed up internally as one of the magnets disintegrated and parts of it got
caught up between the frame and armature. Hadn't seen that before.

Jim

[peteski]

One of my Lifelike/Walthers SW1200's stopped running, the motor jammed up internally as one of the magnets disintegrated and parts of it got
caught up between the frame and armature. Hadn't seen that before.

Jim

In my SW1200s the open frame motors (similar to Kato and Atlas) use black ceramic magnets, not the Neodymium magnets discussed here. Ceramic magnets aren't prone to the type of damage seen here, but they can shatter like glass when exposed to external force.  Unless at some point LifeLike/Walthers changed the type of magnets used in their open frame motors?

[spookshow]

Are these BLI or PCM E units?

PCM didn't use Paragon decoders, they used LokSound. My dead ones are all BLI's with Paragon2.

-Mark

[u18b]

One of my Lifelike/Walthers SW1200's stopped running, the motor jammed up internally as one of the magnets disintegrated and parts of it got
caught up between the frame and armature. Hadn't seen that before.

Jim

I agree with what Pete said.   What you experienced, and I have seen lists of times is the ceramic magnets coming unglued and so they float around.   I’m guessing that what may have happened to yours and how they got damaged.