N scale Kato motor problem

[PED]

I have a N scale Kato SD40-2 where the motor will not run correctly. I bought it several years ago off a popular aution site.  Supposedly new. I have motor out and am trying to run it directly on VDC. Motor will start if I give it a nudge by hand but only at higher speeds. Will not run at slow speed. I assumed the motor was tight and needed a break in period so I have had it running in both directions for over an hour but it still acts the same. I would expect the motor to run OK after an hour of running if the problem was just a tight motor. However, since it still acts the same, I am now assuming some other problem such as a bent shaft. Sounds like I need to replace it.

Does my analysis sound about right?

[rrinker]

 Could be like on HOO loco I had, the glue/epoxy used to hoold the commutator segemtns in place was over-applied and covered oone whole segment and parts of two others. This insulated those segments from the brushes. You can guess where the motor stopped every time. Turning it by hand past the bad segment allowed it to run, but it was rough and would stall at slow speeds and if stopped would not self-start. Simple fix was to put a new motor in. Then I took the old one apart and discovered what was causing the problem. Some of it flaked away as it didn;t adhere to the copper very well, but it wasn;t nice and clean and I didn;t trust the motor to be reliable, especially combined with my disassembly. 

 Replcing the motor is probably the best bet. You may be able to order one from kato. Or find another of the same loco with a busted shell and use the chassis for parts for the one with the good shell.

                                               --Randy

 

[PED]

Randy....funny you should mention that issue. My Kato does not have that problem. Inside of motor looks clean. However, I have an Atlas loco with exactly the problem you mentioned. I tried to chip some of glue away but it was too hard and too much of it. Looks like I have two locos to re-motor.

[Spalato68]

Paul,

 

I had the same issue with three pole motor of racing car of my friend. It would not start itself, i had to turn it by hand, after that it worked well until I dropped the voltage so it turned slowly – it stopped then.

 

 

I tried everything, cleaning commutator and brushes, adjusted tension of brush spring – nothing worked. Then it came to my mind – maybe there is a “bad solder” point (I do not know how to say in English – when you solder something, it looks OK, but in fact, it is not – there is no electrical connection – in Croatian we say “cold solder”).

 

Anyway, I just touched with hot iron (narrow tip) all three contacts on commutator where windings were soldered to commutator. After that, motor immediately started to work normally.

 

 

Before changing the motor, you can try this, you have nothing to lose. Of course, be careful with iron, not to melt the whole commutator.

 

 

Even before trying to help with iron, try to clean commutator and brushes first (althought they look clean, maybe the are not). If oil penetrated to commutator, then all has to be cleaned – commutator, brushes, brushes holder, springs, and commutator grooves (use a toothpick, not any metal object!).

 

 

Regards,

 

Hrvoje

[BigDaddy]

Spalato68

there is no electrical connection – in Croatian we say “cold solder”).

Same over here.

[PED]

I found a motor so I am going to replace it. However, I will check the solder connections of the bad motor if I can. This is N scale so it is really hard for a 75 year old guy with shakey hands to work on such tiny stuff.