need help diagnosing burnt arduino nano v3

Sembazuru:

csurf:

CrossRoads:
No 3.3V, No USB connection - what else is there?

so would the FTDI going bad cause the Tx & Rx LEDS to stay lit and cause the board to not work even when not using the USB connection (using the external ISP programmer) ???
I'm confused about this...

The RX and TX LEDs are driven by the FTDI chip, but as active low signals. I suppose grounding the power to gnd pins on the FTDI and then applying signal voltages to it's input pins could cause damage. The currently damaged FTDI chip may be causing other odd behavior through it's interconnects to the Atmega.

It might be an interesting exercise to remove the FTDI chip and then try to program the Atmega with ICSP. (Of course, make sure none of the lands in the FTDI's footprint are shorted with leftover solder from the removal process...) :wink:

After messing with it a lot, i finally got the board back online...
It turns out that I had damaged a couple of the pads when I had initially freaked out & removed all of the header pins from the board (yes, i know, it was a stupid move, but I was desperate & a little drunk, so I started manhandling the board in order to remove all of the pins).

It turned out that the MISO connection on the D12 pad was damaged, and it wasn't making it through from the ICSP header to the MCU.
The 5V pad was also damaged, and I had idiotically jumper'ed it to the wrong location.

Once I fixed those two problems, the FTDI chip came back to life.
I was also able to get communication up between the MCU and avrdude using my external programmer.
At first, it struggled to successfully upload sketches, and would error out every couple of attempts .
The other weird thing is that programming via USB still didn't work; I would still get the 'getsync' error.
So, out of desperation, I tried re-burning the bootloader with the external programmer.
After that finished successfully, USB programming started working again, and the uploads via the external programmer no longer had any issues...

So, now, I have a 'crippled' yet functional board (the 5V and D12 pins are no longer useful as they've got jumper wires in their place).
Still, I'm stoked that its not a total loss...If I need 5V, I guess that I'll just have to tap into the ICSP 5V pin or figure something else out.

Thanks for the help you guys! :slight_smile: