MDC/Roundhouse 2-8-0 and 2-6-0

[ATSF_Ron]

I can report 99.9% success today!  It runs almost perfectly.  When I say almost, there is a brief short that happens in turns.  I know what it is and can easily fix it.  If you look at my photo of the drawbar connection to the tender, you can see the contact piece is on the wrong side of the metal post coming out of the tender.  It should be on the opposite side.  Then the contact piece won't be able to touch the front tender wheel like it is in my photo.  Chris's pics clarify the correct way to install it.  The other issue is the plastic piece that snaps into the post on the locomotive.  It WILL NOT go in, and I don't want to break it.  So...I will once again remove the shell so I can loosen the screws that hold the loco frame halves together, thereby allowing said plastic piece to drop easily into the post.

Thanks to all who gave advice or contributed helpful info on this project!

Ron

[Chris333]

It is hard to pay those collector prices when all I want is the drivers and gears, the rest gets tossed away. Well no I give the extra parts away. But still 

[ATSF_Ron]

W...T...H??  As you can see, I'm getting power since the headlight works.  No hum, no nothing from the motor.  I don't get it.  The LED is soldered to each half of the loco frame, so why is the headlight on but the motor seems dead? Hmmm.  I have the coal load off, so if I turn the motor with my finger I can see the drivers turn slowly.  Nothing seems like it's jammed.  Obviously the worm is working or the wheels wouldn't turn with my finger.  Seems like there's no power to the motor but obviously there's power to the light.  The mogul behind the one on the track was my example to check all of the electrical connections.  They are identical.  That one runs, this one doesn't.  I'm stumped.  Any thoughts guys?

[ATSF_Ron]

Ok as soon as I posted this I had a thought.  I disconnected the tender from the loco to see if it ran on its own like before.  Bingo!  It does.  So that would suggest a drawbar issue, correct?  But then, why do the lights work but not the motor?

And after I typed that last sentence I tried it again.  Nothing!  WTF??  I put the other loco on the track and it runs but the other one doesn't while on the track at the same time.  I spun the motor with my finger again and then it started up.  Hmmm.  Tender to track connection?  I've never had that thing apart and I'm a bit hesitant.  I hear there's very fine wiring in there.  Or maybe that's the connie.  I'm not sure.  Time to go poke around some more...

[dangerboy81]

I had an Atlas motor do that to me. It would only run if I gave the motor a little spin with my finger. I cleaned where the brushes make contact with the motor...
the commutator? I don't know the name for it, but that made it run again.

[Lemosteam]

Get your multi meter out and check for continuity from the wheels to the brush cap on each side. Something is not connected to one rail or the other.

Pull the tender off, put it on the tracks and then check for continuity to the brush caps.

Add throttle and check for voltage from the track to the brush caps.

If none of these work, then there is a disconnect in the tender assembly.

[ATSF_Ron]

I tried poking around without taking anything apart yet.  Here's what's happening.  In my last photo looking down on the motor, there are what I believe are the 5 "poles" in this motor.  These are the green colored pieces.  If that is not the correct term then someone please correct me.  On either side of the green poles are what I believe are magnets.  If I press down lightly on the fireman's side magnet, the motor stops.  When I press on the engineer's side it starts again.  I checked the screws at the four corners of the tender and 3 of them were loose.  I tightened them up and now I can still get the motor to stop, but as soon as I take my finger off the magnet it starts up again and runs fine.  Seems like an intermittent electrical issue down in there.  Again, I'm hesitant to take it apart if there are tiny wires and fragile parts in there.  Chris333 or anyone else, have you had your tenders apart on the mogul?  If so, can you comment on what's going on electrically in there if you know?  Thanks!

[ATSF_Ron]

Lemosteam, thanks for that info but I'm not even sure what the brush caps look like, lol!  I'm not well versed electrically or in opening up motors.  I do have a multi meter though.

[Lemosteam]

The silver circular thins on the side of the black part of the motor. Each side corresponds to a rail. If there is no connection between the rail and that cap, the motor cannot get power from the track.

[ATSF_Ron]

I'm cautiously optimistic.  After tightening down the motor mount screws in the tender it seemed to eliminate the problem.  I snapped the coal load back in and have been doing some testing around curves and through turnouts for about 10 minutes.  So far, so good!  Tomorrow will be some roundy round break-in running on the unitrak test loop.  And in case anyone is curious no, I'm not a fan of the Rapido coupler, nor do I use that type.  I have to find a Micro trains conversion.  Sadly, Athearn no longer stocks the Micro trains pilot for these locos.

[Chris333]

I turned mine into a HOn30 loco:


Maybe the coal load was enough to hold the 2 silver spring contacts to the floor?

[nkalanaga]

I looked on the N Scale Supply site, and they don't list a MT conversion specifically for these locos.  But one of these should fit, and each will do two locos:
https://www.nscalesupply.com/mtl/mtl-magnematicnscalecouplerstruckmountcouplers.html

(I imagine they're available from other dealers, or direct from Micro-Trains, but I have NSS's catalog bookmarked)

[mmagliaro]

Motors of that type are notorious for having one or both magnets break loose from the frame.  They will look fine, as yours do in the photo,
and as long as everything is "just so", the motor will run.  But pushing on it this way or that, tightening/loosening screws, etc, will allow
one of the magnets to just graze the armature and block it from turning.

Also, what about that flywheel.  It looks really close to the cavity walls.  Can it graze the surfaces if the 4 corner screws aren't perfectly tightened evenly?

The motor has no fragile wiring to it.  If you take out the 4 screws in the corners of the body as shown in your photo, that "rim" comes right off.  Then you will have clear access to the brush caps.  Note: The left-side brush cap actually goes to the right-side rail and vise versa, just in case you do some testing with a voltmeter.

As for "tightening the motor mount screws in the tender", I assume you meant those 4 screws in the corners.  Those have nothing to do with mounting the motor.  In fact, as I just described, you can take those out and lift off the entire body, and the motor is still firmly mounted in place.  What actually holds it in are the two screws that hold the trucks on from the bottom.  They go through the trucks, up through the tender bottom, and into threaded holes in a plastic piece under the motor.  If you take those screws and the trucks out, you can lift the motor right out.  Make sure to note that when you put it back in, there is the tang in the front center that goes down through the floor and contacts the spring coil ring on the draw bar.

Anyway, tightening those screws should have done absolutely nothing.  Since you say that "fixed" it, I suspect  sheer coincidence or a physical bind in the motor (like the magnet problem I mentioned), where tightening those screws is just twisting the underframe enough to get it to run.  On mine, in fact, there are only 2 screws in opposite corners.  Two were completely missing from the factory.

[ATSF_Ron]

Chris, great job on that HOn30 loco!

Max, thanks for that info.  As long as this loco runs like it has been, I'm leaving it alone!  Thanks for all the tender info though.  I may need it if things go south again.  I was doing for switching with it earlier and all seems fine. (Knock on wood!)

[badlandnp]

It has been a while since I have been on this forum, life gets busy. Anyway, these are great little loco's, and solid runners. I have one that I run all the time, which i have remotored, The remotoring required some custom mounts, but it worked. I also added an NCE DZ14SR decoder to the top of the coal load and ran headlight wires under the walkway, and a firebox LED. It is one of my most reliable locos and is a beast for "tonnage."

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