Carelessly I applied 12V to the 5V pin while breadboarding a project.

I now get no signs of life from the board. And applying 9V via the board's jack socket from my bench power supply indicates a direct short.

I've placed an order for a replacement board but, expense apart, it seems such a waste. Is there a fuse anywhere or anything else I can try to repair it please?

(I've posted simultaneously here and to the arduino.cc forum.)

Terry, East Grinstead, UK

 

hi Terry,
Applying 12v to the regulated 5v internal line has most likely taken out a number of components, it will be a task to trace and replace dead components.
Sadly, it's a write off.
E

 

Thanks Eric. I fear you're right.

In case it offers a further clue, with the 328 chip removed both the 5V and 3.3V pins are grounded. I see nothing visibly wrong on either top or bottom of the board. I was just wondering if it would be worth replacing the 3-pin regulator chip next to the jack socket, an AMS1117?

I expect delivery of a replacement UNO R3 tomorrow.

Must redouble my caution, or this could become an expensive hobby!

 

In case it offers a further clue, with the 328 chip removed both the 5V and 3.3V pins are grounded. I see nothing visibly wrong on either top or bottom of the board. I was just wondering if it would be worth replacing the 3-pin regulator chip next to the jack socket, an AMS1117?

You probably took out both microcontrollers too.

Must redouble my caution, or this could become an expensive hobby!

Use this as a learning opportunity and don't make that mistake again.

 

Maybe try to power up the 328 up on breadboard see if he's dead or not. Probably so, but still a fun project if you have time to burn.
When your new one comes in you can use it to compare the bad one and easily trace out your faults using a dmm or curve tracer. Again, as a fun project.

 

Remove the 5 volt regulator. If the short goes away, a new regulator may fix it.
If not, try the same with the 3.3 volt regulator.