F7A DC, Motor issue

[LedHed430]

The issue: The motor runs but it has to be "kick-started", which cannot be accomplished with the trucks on. Runs at various speeds and voltages until stopped then has to be "kick-started" again.

Background: New N-Scale locomotive from a Stallion starter set. Worked well for about a half hour or so, after that only the headlight worked. There was evidence that it may have had a rough ride on the way to my house. The rear truck cover was loose but snapped back in place easily. I haven't checked the other cars in the set yet. Popped the shell and pulled the trucks, no visible connection issues between wheels and chassis.

Layout and power supply have been illuminated, other locomotives work fine. 

"Bench tested" the chassis... Jumpered the chassis halves to the power supply from the starter set via the rerailer section of track eliminating the trucks as a connection issue. Still no motor response only the headlight worked. Spun the worm gear with power at around 50% and VIOLA! The motor runs.

Once spinning the motor operates normally until stopped, even with a slight load applied to the flywheel or worm gear. Once stopped it won't restart until I spin the worm gear or flywheel again.

Questions: Is this a common problem? Is it repairable: connection between chassis, DC board and/or motor? Is it a motor issue: armature/field windings, replace the motor?

Any advice would be appreciated.

Richard

[Mike C]

This sounds like the motor has a broken wire on the inside . Pretty much impossible to repair , you will probably need a new motor . I'd return it under warranty for replacement .

[LedHed430]

Looking more and more like internal motor problems.

Towed the newer F7A with another locomotive from a slightly older (two weeks) Stallion starter set and got the motor to run. After running them tandem for a while I pulled the good engine off the track and there was a huge difference in speed.

I timed both locomotives on my outer 8' x 2.5' oval at the same track voltage and there was 5 seconds difference in lap times. At 18 vdc on the track the good engine would turn a lap in 9 seconds the bad motor took 14 seconds. I know there are variances between locomotives even of the same brand and type, but that seems like a little too much. The problem motor also stopped pulling around 6-7 vdc versus 2-3 for the good one.

Looks like a one way trip to Pennsylvania might be in the future for the new F7A.

Rich

[James in FL]

My first thought on this, is that your lokie may have a break in the wire in the windings of one of the poles of the motor.
Repairable? Yes, if you rewind the motor.
If this proves true, I would buy another motor rather than to try and rewind.
My rewinding efforts do not produce equal results as a factory wound motor.
My experience tells me that the wire tension, and wrap count, of the wire is critical and must be maintained.
I have found this tension difficult to maintain throughout the entire windings.
Not impossible, but not my Forte.
YMMV  

You've already checked the brushes and their springs yes?

Good luck

[LedHed430]

I haven't checked the brushes and springs/holders for a few reasons:

1. I wasn't sure if the motor had brushes.
2. Further dis-assembly may void the warranty.
3. Inexperience may lead to irrevocable harm the locomotive, see #2.
4. Weighing shipping costs of sending the engine back under warranty vs. ordering a motor.

The entire set is packed back in it's original box and my need... desire, for a second locomotive has subsided. I'm focusing more on my layout rather than the number of cars I can pull. So I don't have to have the motor fixed right away and warranty repair/replacement seems the more likely option.

Rich

PS. I got the original locomotive up to 26 cars after adding an ounce to the locomotive.