jwatte

I have an old (10 years or so) Nikko RC toy humvee, which I'm starting to re-purpose.

It has two differential axles, each with a single motor, which I believe is a plain DC gearmotor. Applying power makes it "go" in the appropriate direction, so no sensors involved (at least on the outside) and thus unlikely to be brushless.

One time out of ten or twenty, the motor refuses to actually start when power is applied. Removing power and adding it again will make it go. Also, turning the wheels a little bit (like you'd get by the other motor working) seems to make it work. But... this makes it a 1:100 chance that neither motor will go and it won't start!

However, there is a third, mysterious, thin green wire coming out of the motors. I'd like to know what this is for. Is it for some sensor to avoid this no-start? Is it a thermistor to prevent over-heating? Something else?

Here's a link to three pictures of the truck in question but I really only want help with the motors. A data sheet or description link of some sort would be awesome!

https://plus.google.com/115565509658...ts/7Bq4TWPQFzR

jwatte

I swung by Tech Shop this evening, and checked out the green wire on a scope. It appears that, when the motor is running, it is ground level, but when I supply power (PWM, actually) and the wheel is stalled, it comes out at about 1/2 the PWM voltage with the square PWM shape.