FDTI chip burnt?

Hi, I've a Arduino Duemilanove, which stopped to communicate to the PC from yesterday (it worked flawlessly for a year). The last program loaded in ATMega328 works, but I can't to program it, because when I insert the cable in USB port the PC doesn't recognize it. Under Linux if I use dmesg no message appears, the same under Windows. I fear that I burned the FDTI chip: a few days ago I connected the 5V pin with ground (I've made a mistake) only for a few seconds, but maybe this burned the chip. Now if I check the voltage on 3.3 V pin the voltage is 5V , not 3.3 V. Has someone got a similar experience? Should I buy a new Arduino? Thanks.

Are you handy with a soldering iron? You could try removing the FTDI chip & installing a new one if you are sure that is what the problem is. Or remove it, & install some header pins so you can program it with an FTDI adapter board, same as programming a pro-mini.

Now if I check the voltage on 3.3 V pin the voltage is 5V , not 3.3 V.

That is a pretty good sign you burned out the FTDI. Its onboard 3v3 regulator is what provides the 3v3 supply on the FTDI-based Arduinos.

If you continue to you use this board, you should consider cutting or lifting the 5V pin on the FTDI. You'll want to make sure it isn't drawing unnecessary current.

@James Thanks, I'm not so handy with soldering iron, I don't think that I'll remove the FDTI. @CrossRoads: How can I do to cut the 5V pin on the FDTI (I'm a newbie...)? Any helps is appreciated. Thanks

See its datasheet http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232R.pdf Figure 3.1. Pins 4 & 20 are the 5V going into the chip.

You can make yourself a little cable and connect the appropriate pins to something like this so you can keep programming. http://www.sparkfun.com/products/10008 If you look at the Duemilanove schematic and the FTDI Basic schematic, you can see this is pins 1,2,5,11 from the FTDI chip along with +5 & GND. http://www.sparkfun.com/datasheets/DevTools/Arduino/FTDI%20Basic-v13-5V.pdf If you look at the Promini, you can see that RX & TX go direct from the FTDI to the ATMega pins, with DTR going to the reset circuit. Maybe connecting like that would be better. Then you could access the larger pads at the bottom of the J1 socket for RX & TX, DTR at the RESET-EN pads next to the USB connector, and VCC & GND from the power header pads.

I don't know what effect having a dead FTDI connected in parallel would have. If you had some smaller cutters, I suppose you could try snipping the legs at the side of the FTDI chip. For RX/Tx, connecting to the J1 pads would at least give you the 1K resistors to help isolate you a little. I suppose those would pop right off easily with a soldering iron to fully disconnect those lines. Then its really just CTS on pin 2 left to cause any interference.

Many thanks, I’ll try, but I’m not sure to understand all what you say. Thanks again.