I face somewhat strange behavior of motor shield (which I bought from dx.com) and DC geared motor. http://imgur.com/pyZFcY2
I use following code to run motor:
pwm = map(speed, 0,100, 0,255);
And my power source is 5xAA.
When I connect motor with 0.68uF capacitor, motor twitches and stops. When I connect motor with 0.1uF, motor runs for about minute (or 10sec, or 3mins) and stops. Bizzare thing is when I touch shield's motor terminals with multimeter, motor runs without problems for at least 5 mins.
I am a bit stuck here. I know that shield is not original and I found out that C7 and C8 are differens - they're 100uF 16v instead of 47uF 25V. Dunno if it has something to do with this issue.
Oh yeah, I have tried also separate power source for arduino and motors with same effect.
Also, arduino does not seem to reset or "freeze" - I have led blinking all the time without interruption.
Can someone explain me what is going on and point me out to the direction of troubleshooting?