Is my Arduino Uno broken?

I succeed to install my Arduino Uno today. The Blink worked. Then I tried to connect servo. And after few tests, the Arduinos L-led turned off and now my computer won't find Arduino anymore. What can I do? Or is my Arduino broken :(? Green ON-led still lights. But L doesn't.

I tried with an other computer and it doesn’t detect Uno either. Is there anything I can do? Reseting or something? Or is this Uno gone for good?

I’m total beginner with bad english (from Finland), so I really need your help. Please… :-/

How did you connect the servo? Are you sure you didn't do any short circuit or draw too much power?

Do you heard any song when you plug the usb cable?
Does the device appear in the device manager (windows?)?

What is the last thing you did (when it was working)?

Device doesn’t appear to device manager. There is only COM1. At first Uno appeared to COM4. I run Blink from Examples and it worked well.
Then I tried servo. Servo’s code is below. After uploading, servo worked few times. After that, there is only green ON-light and I can’t find Uno from Device manager anymore.

Now I’m wondering, how can I reset Uno. Or could it help?

Here’s the code:
// servoRange.pde - Send increasing pulse to Arduino
// and show values in serial console
// (c) Kimmo Karvinen & Tero Karvinen

int servoFrontPin=2;

void pulseServo(int servoPin, int pulseLenUs)
digitalWrite(servoPin, HIGH);
digitalWrite(servoPin, LOW);

void setup()
pinMode(servoFrontPin, OUTPUT);

void loop()
for (int i=1; i<=3000; i=i+2) {
pulseServo(servoFrontPin, i);

How did you wire up the servo? It could be that you overloaded the USB bus.
It is normal to run servos from a separate power supply.

That's probably the reason. I put the red conducting wire to board's +5V pin. What should I do now? Or have I already smashed it down :(?

Same as here:

Just replace the illustrated 9V battery with a better power source

I put the red conducting wire to board's +5V pin

So you put the red wire from a 9v battery into the 5v line of an arduino?

What should I do now?

Buy a new one.
The processor might have survived you can try that in your next board.

Thanks for that. I'll try that, when/if I get my Uno work again. Now the problem is, that board doesn't appear to Device Manager anymore. Any ideas for that? What should I do if I have "overloaded the USB bus"?

Quote: "So you put the red wire from a 9v battery into the 5v line of an arduino?"

No, I put the red wire of servo to 5V line of Arduino. I didn't use any batteries yet.

Sorry i don't think you understood. If you have put 9V into the arduino you have destroyed it. Buy a new one.

If it is only the servo you connected to the 5V line then it is possible that you have just blown the power side of the arduino.

You can test this by connecting a 9V battery or external supply to the power in jack.
If it still doesn't work you have blown up your arduino and you need to buy a new one.

You could have blown up the USB socket on your PC so try another socket or another PC.

Yes, I suppose so... Perhaps I order Duemilanove.

Arduino's green ON-light still works, when I connect it via USB-cable. Is there anything I could try with this board before the new one comes?

You have disconnected everything from the board and tried to up load the blink sketch have you?
As the green LED is on it suggests that the USB fuse is not burned out. But it looks like there is something wrong with the 8U2 processor.

Yes, I tried that and I get this message:
Binary sketch size: 1010 bytes (of a 32256 byte maximum)
avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

And I can't find the right serial port. Arduino doesn't appear to Device Manager anymore. (It was there at first.)

Did you try another lead, another USB port, another computer?

Yes, I tried all of those. From troubleshooting I found this:
"Disconnect digital pins 0 and 1 while uploading (they can connected and used after the code has been uploaded)."

How can I do that?

Do you have things plugged in to digital pins 0 and 1? If not, then that tip doesn't apply to you. If so, it should be fairly evident what you need to do.

Ok, thanks :-). I decided to order new Arduino, Duemilanove this time. I think, that Uno is broken, because even Blink won't work anymore. At first it did. I tried with few other computers, with the same result: they don't recognize Uno. It won''t appear to Device Manager.

Thaks for your advice. It's really nice to have forum like this :slight_smile: