Arduino UNO Pin GND/5V problem

Hi to everyone.

I started this summer to make things with Arduino. I wanted to use some servos attached to Arduino.And,i bought an Arduino Uno. I has been working with it and with one mini servo motor for a lot of time withough problems and it worked well. But few days ago a problem with GND/5V pin (i don't know wich of this have the problem or it's both) when i put a wire inside the Arduino disconnect from PC and turn off and the resistor is hot.And when i quit the wire the Arduino works again. I have my servo,yellow wire to pin 9,black wire to GND and red wire to 5v. The problem happens when i have pin9,gnd in arduino and then i put the red wire in 5v or when i have pin9,5V and i put the black wire in GND.

I don't know how it happens and it has been worried me so much. And from now i can't continue working with my project for this. I guess if my Arduino is damaged or could be damaged with that. I need help to fix this.

I hope that some of you could help me. I would be so glad.


Sounds like either your motor is bad or is drawing more power than you can get over USB. Do you have a link for the motor?

The servos are this: HextronikHXT900

It's extrange because i has been working with them about 2 weeks,using USB power withough problems.

From feedback from one of the users of that servo:

There is a downside of beeing strong and fast, they draw quite a bit of current. I measured about 550mA when exercising one HXT900 without load. This is an average, it seems to require more peak current. If used together with a linear BEC it will cause voltage drops.

That would imply that you should never try and power even one of these from the arduino 5V pin. Servos have motors that require current dependent on model, size, travel distance, and load on the servos, etc. Arduino boards are great at CONTROLLING stuff but not very good at POWERING stuff. Use an external power source for the servos, you will have much better luck in your projects.


Nope, not strange actually. If the motors really do draw more than 500mA, you've been exercising the Arduino's on-board poly-fuse which increases resistance over time when its rated value is exceeded. (They don't just "blow" at their rated current like traditional fuses.")