arduino mega 2560 and arduino motor shield REV3

I used the arduino uno R3 with the arduino motor shield REV3 and two motors (12volt) and everything went just like it has to be. (on a selfmade diy putchroboter from conrad)(separated accu)
But i want more sensors on the robot. So i mounted the arduino mega on the robot and started it with the same sketch.
For 10 seconds everything went well, and then it stops (everything interupted) and reset again up and waited for me to start again. i did but again, now almost directly it stops. I felt the mega (around the voltage regulator ams1117 5v) was warm.

my question is : does arduino mega and the arduino motor shield REV3 works together without changing
the sketch or other things?

thanks

Guido

For Almost all motor shields there is an option of external power.
There is usually a jumper or track pad to cut.

Start there and supply EXTERNAL power to your motors.

An actual LINK to the motor board supplier would be great to have as there are even Chinese versions of R3 motor shields that are not all the same.

It sounds like your mega is cutting out because you are trying to draw too much from it.