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Topic: Is my board damaged? (Read 581 times) previous topic - next topic


Jan 01, 2008, 01:09 am Last Edit: Jan 01, 2008, 01:22 am by pathfinder007 Reason: 1
I followed the potentiometer connection on the arduino tut website.
The connection is two ends of the potentiometer to the +ve rail and ground and the middle connection to the arduino analog input pin.
When fiddling around, I mindlessly adjusted the potentiometer to its lowest R value which is around 1ohm, so with this connection it's effectively shorting the Arduino 5v supply to the ground assuming the analog this pin has infinite resistance, which seems to be the case because the microcontroller seems to be operating well. But I am afraid the voltage regulator might be damage, because after that event, the 3.3 voltage rail was gone, couldn't measure any voltage out of it, but the strange thing is after I reconnected the USB and IO connections again, it was working again.
I don't get it, so is my board damaged, how can I check it?

I had a look at the schematic digram of the Arduino Diecimila which is the one I have.
Because I was using USB power so I think the voltage regulator should be safe.
There is this F1 component which has a 500mA label near it, is this a fuse of some sort?
Is it possible that this thing is blown?


Hmm, adjusting the potentiometer doesn't change the resistance between the two "ends" (just how much is to either side of the middle connection), so assuming you hooked it up right, it shouldn't have shorted +5V to ground.  What did you see happen that makes you think the board got shorted?  Did the power LED go out?


Sorry, I realize that as well.
Yes, at the time when this happened, the controller was driving a stepper motor, and the delay between the pulses to each windings was controlled by the potentiometer analog input, so I guess by adjusting the potentiometer to the lowest resistance value, the motor went a little crazy, and when the inductive load goes a little crazy it's not good for the ground, but my system was fully isolated, so I don't see how the motor can affect the Arduino board.
Now the board is operating well, it was just for that very short period of time, I couldn't measure any voltage on the 3.3v supply coming out of the Arduino board, but as soon as I disconnected the USB and reconnected it again, everything went back to normal, so I guess I just worry too much.

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