KATO NW-2 Motors

[joelm]

Hey Kids:  NW-2 motor died (has anyone else had this happen? I think this is my second one) Kato showing out of stock. Are there any other loco's that use the same motor that I could substitute?  Thanks, Joel

[peteski]

GS-4 loco uses the same motor, but the flywheel and coupling is different.
What exactly do you mean by "died".  What is the specific problem?  Motors are fairly simple and robust electric devices.  Maybe we can fix it. 

[joelm]

Pete: Good question.  I appreciate the offer.  Here's the sequence of events. Loco stopped working during an ops session. This has happened before with other locos- usually turned out to be a scrambled decoder, a reset or reprogramming typically handles it.

My troubleshooting was a follows: 

Using Decoder Pro on a workbench track, using a Sprog II v.3. NW-2 had a Digitrax Decoder.
1) Set Decoder Pro Throttle to address - only got light, but light responded both directions.
2) Tried to reprogram decoder with stored info. could only get lights, no movement. Decoder Pro message: "no loco detected" during reprogram effort. (Did not stutter or blink during this effort-bad decoder?)
3) Tried to factory reset.  Decoder Pro message: "no loco detected" during reprogram effort.(Did not stutter or blink during this effort, and no action.  so assumed dead decoder). 
4) Changed to new TCS decoder. Decoder Pro message: "no loco detected" during reprogram effort.(Did not stutter or blink during this effort, and no action.)  Second dead decoder? Not likely.[/size] 
5) Remove TCS decoder, set loco in cradle, run test leads from layout to motor tabs, set DT 400 to address 00, throttle up. No action. (Tested on F-3 motor, worked.)

Sounds to me like a dead motor.  What can be done to FIX that? Thanks. [/size]

[Steveruger45]

Hmmm.It sounds like the decoders are not registering a connection to the motor. To start I would suggest take the motor out and try running it on dc with a dc power pack or a 9v battery if you don’t have the former. Then, if it’s still a problem  I think I would take out the brushes and check them and their springs are ok and Make sure the motor armature spins freely and Check and if needed clean the commutator and sparingly lube the bearings. In my experience I’ve never had a loco motor burn out it’s windings but I have had a very few where the brushes either cracked, broke got stuck so they didn’t touch the commutator  or the brush springs were damaged or weak causing similar issues.  If the motor runs ok on dc then it maybe a connection problem with the decoders.

[CRL]

The only motors I ever cooked were accompanied by a definite “what’s that smell” incident.

[peteski]

 Motors are just bunch of copper wire wound on steel armature, magnets, some copper segments in the commutator, carbon/graphite brushes and some plastic. Not much can go bad in them, and if it does, you will very likely smell things burning or even see some flames. Yes, I agree with Steve and CRL.  Steve offered some good troubleshooting info.

 If you don't have DC throttle handy, like Steve mentioned, a fresh 9V battery can be used as a DC power source to test the motor.  I usually have a 9V battery handy, even when I go to model train shows, as a quick loco tester.

[mmagliaro]

Your item #5 sounds like it "almost" tests the plain motor with no decoder.  But it would still be better to test it on plain DC or a battery instead of a DCC system set on address 0.

What else can you do?  Well, if you take the motor out, try it on a 9v battery, and it still won't spin:

I would
a) See if the motor hums, vibrates, or gets warm when you try it on DC.  If not, suspect a bum brush or brush spring in one of the holders.  Try taking them out, make the sure the brushes and springs are not broken or bent up.

b) Put an ammeter in line with the DC when you try it.  See if it's drawing any current (or a LOT of current, like more than 250 ma).  Although if it's not getting warm or humming, I doubt it will.  Still important to know.

If it's drawing a lot of current, try cleaning out the commutator slots with a pointy wooden toothpick.  If it's drawing no current and the brushes are good, the armature is probably shot.

If you try all this, and it still won't turn or even hum, I'd say there is a broken or burned coil wire and the motor has probably had it. 

But this doesn't happen very often.  In fact, I don't think I have ever had a single motor just completely fail like that.  Usually, they run hot, run slow, get fussy about starting, etc... all of which are indications of brush or commutator problems.

I don't think I've ever had a loco actually "burn out".

[peteski]

Pete: Good question.  I appreciate the offer.
 . . .
Sounds to me like a dead motor.  What can be done to FIX that? Thanks. [/size]

If all else fails, you can sent it to me, and I can see if I can do some magic. 

[randgust]

The 'prove it's dead' always starts with straight DC, test prods direct to the brush holders and nothing else connected anywhere.

And the NW2 motor is not particularly difficult to get out of the split frame, gear case and all.

The sides of the commutator on an NW2 are open, so you can at least see what's going on in there.   I've used micro alligator clips and a VOM multitester to start checking the motor, clipping in a needle on them lets you get into tiny places to test.   Basically there are two conditions you can run into on a truly cooked motor; 1)  The motor is 'burned out'; i.e. someplace inside the windings or connections a wire has actually burned through.   Most motors with one burned or disconnected pole will still spin with some finger help but periodically stop with no way to restart.   The VOM multitester will show no resistance if you connect accross two spots on the commutator.

2)is a dead short, meaning two poles have literally melted together and the activated magnetism on conflicting poles prevents the motor from spinning.    You'll see 100% resistance connection across two poles where other poles have some degree of medium resistance for comparison.

If it is burned out or damaged, you can often see physical damage on the connections to the commutator, or in the windings themselves.   The point of failure I've seen most often (old Rivarossi motors died a lot!) is a motor getting so hot that the connection to the commutator (soldered) would fail and pop off.    That can actually be resoldered if you're up to it.    Once in the 70's I actually found the burned wire hanging out of the armature and successfully reconnected it and it worked...again, Rivarossi.

In the last 20 years I think I've had maybe one motor fail, and that was the finger brushes on a Tomytec chassis motor (Identical to some Bachmann).    But I've had probably 5 decoders drive me absolutely batty including episodes of magic smoke. 

[nickelplate759]

maybe it's the lack of coffee this morning and I'm confused,  but @randgust - didn't you mean that a burnt out coil would should infinite resistance, and a shorted coil would show none?

[peteski]

maybe it's the lack of coffee this morning and I'm confused,  but @randgust - didn't you mean that a burnt out coil would should infinite resistance, and a shorted coil would show none?

I find Rand's post a bit confusing too, and you are correct about what short and open is.

Problem with checking the winding in a motor like this (even if you can access the commutator directly) is that more than one winding is connected to each commutator segment, so you are not really ever running a test on a single winding (the other winding come into play too).  Sure, with several readings taken aroud the commutator, and some thinking, you should be able to deduce the status of the windings, but it is not very straightforward.

[joelm]

Gents: Thanks for the suggestions. I will try the battery. One of my local crew is on the Railwire (DerWolf) and he has volunteered to take a look at it. I don't think I'm personally up for the challenge of taking apart the  motor to inspect the parts. I'm not sure I would know what I was looking at or what to look for, nor be able to put it back together and have it work.   Yes, I know MRR is supposed to challenge me, but this may be "a bridge too far".  Thanks, Joel

[joelm]

An Update:  Wolf came by Saturday. The motor worked with the 9 v battery, so thanks for that troubleshooting step!  That narrowed it down to a contact issue between the wheels and the motor contacts.  The Kato brass contact clips used on the NW-2 offer minimal contact area, so Wolf tightened them. That didn't work, but we then noticed the decoder was a little loose, so Wolf put a small bit of solder on the decoder contact plate (where the decoder slides into place and contacts the frame halves).  That solved the contact problem, in that the loco now ran.  However, while the decoder responds to address 03 and runs (I reset to factory 8 during my initial troubleshooting), it is not responding to re-programming through Decoder Pro.  It blinks like it's getting the data, but doesn't respond to the new address.  Thoughts?  Thanks, Joel

[Steveruger45]

Good news Joel, glad some of the trouble shooting steps helped.
For your decoder problem, it may not have reset correctly initially due to the connection issues which now resolved.  I would recommend to first do another reset and then interrupt the power for a few seconds by lifting the loco off the track or tilting it.  Then try decoder pro again.

[NtheBasement]

Glad its resolved.  BTW if the problem was with pickup at the wheels the headlight would not have worked nor would your dcc be able to "see" the loco on the programming track.