View Full Version : MR02i intermitent loss of drive problem

2011.01.17, 04:11 PM
I have MR02i that has developed a strange problem:
after few seconds of driving, the motor stops responding forward or reverse, but steering is working fine. Then the car starts do respond again and within few second problem repeats...
Any idea what might be causing this?

2011.01.17, 05:12 PM
Are you running the stock motor? Is your motor getting very hot? The newer Mini-Z's have a yellow, square thermal cut-off device soldered in series to the motor. It will disrupt the motor circuit if it gets too hot, so I tell everyone who has one to get rid of it.

2011.01.18, 04:37 AM
Thanks for your advise!
I am running x-speed motor. Will check the temperature and remove thermal cut-off device.

2011.01.18, 04:49 PM
I've just checked and the problem is definitely not caused by overheating - it happenes within a few seconds of switching the car on while motor is still cool...
Any ideas what else might be at fault?

2011.01.19, 01:14 AM
hmm.. could be the board or the motor... are the motor wires loose? have you tried a different motor? how long have you had the motor? the brushes might have worn down...

try a new motor in it... if it works then your old motor is the problem... if it still has problems, then your board might be suspect...

hope this helps... :D

2011.01.20, 04:00 AM
Problem solved!
It was caused by loose wire to motor.

2011.01.20, 12:57 PM
For future reference, motor brushes sometimes get stuck, so if you have NO throttle response but steering is fine, give it throttle and roll the rear wheels manually to unstick the brushes.

2011.01.22, 02:34 AM
They are polyswitches and are current dependent*. They are there to protect the board from overcurrent caused by stalled motors given full throttle like if your car gets caught on a railing and your try to pull yourself out with reverse without pulsing the throttle. The boards themselves have no current or temperature protection other than blowing FETs which isn't a very useful.

From time to time cars are unresponsive and erratic upon power up. Cycling the car's power clears this up.

Of course loose motor wires will cause problems too!

*They are technically temperature dependent but this is the device's internal temperature which is dependent on current. Polyswitches are not meant to operate by sensing another components temperature.