user253: I have a Mega 2560 with a ramps 1.4 shield. I noticed when I turn on the 14v power supply the mega would also power up and run. 
Am I damaging it running it at 14v? If not is there a solder or jumper somewhere that I can set it to only run the mega/logic on the usb power? The 14v is just for the stepper motors.

user4664: You can, but you shouldn't, because the the board will heat excessively, as you're out of the recommended range for the input voltage on vin (7-12V).
Unless you have a switching regulator (the one on the board is linear), then you shouldn't' have too much of a difference between the operating voltage and vin as an operating principle because of efficiency (and thus heat) issues.

253: <p>I have a Mega 2560 with a ramps 1.4 shield. I noticed when I turn on the 14v power supply the mega would also power up and run. </p>

<p>Am I damaging it running it at 14v? If not is there a solder or jumper somewhere that I can set it to only run the mega/logic on the usb power? The 14v is just for the stepper motors.</p>
 4664: <p>You <em>can</em>, but you shouldn't, because the the board will heat excessively, as you're out of the recommended range for the input voltage on vin (7-12V).</p>

<p>Unless you have a <em>switching</em> regulator (the one on the board is linear), then you shouldn't' have too much of a difference between the operating voltage and vin as an operating principle because of efficiency (and thus heat) issues.</p>
