Arduino Nano kind of dead HELP

Hi guys

Just got an Arduino nano and stupidly didnt notice it was plugged into usb while i was wiring into the breadboard and shorted +5 and Ground.

Now all i get is a dim pwr LED and cannot flash anything onto the device.

Is there a fuse on these boards somewere which i will need to replace ?

and shorted +5 and Ground.

That in itself won't damage the arduino as all you do is reduce the voltage across it to zero which is safe. However you might have fried your USB port from your computer. Have you tried another USB device on this port?

thanks for the reply but its not the USB port (im a computer technition)

its 100% something in the arduino nano as now the power light is dimmer then before and also the default blink code is not working (it was before the short)

any 1 else any ideas ?

(im a computer technition)

So check the +5V line, what value do you see?
Remove the ATMEGA chip and check again is it 5V?

5v line when running from USB has 1.6V

and its a nano so im not gonna be removing chip lol

atm im trying to find the fuse on the board for the usb side as when powering from the ICSP side with a tinyUSB the nano seems to be fine. (i got the tinyusb as i thought it might of been bootloader)

i onyl posted as i would of expected this to be a common problem and some 1 would be able to say fuse is located here .

ill just have to flash it the hard way im guessin using the tiny usb and power from the vin sockets when using it in my project.

Thanks for all the help anyway

Now iv had time to look at the board iv found the fuse shorted it and usb is now working okay.

if any one else has this problem fuse it located on the underside of the board in between the shield point .

Black device marked B2 this is your fuse.

Thanks
Enlightx

Black device marked B2 this is your fuse.

There are two schematics of the Nano on the Arduino site:

Arduino Nano 3.0 (ATmega328): http://arduino.cc/en/uploads/Main/ArduinoNano30Schematic.pdf

And Arduino Nano 2.3 (ATmega168): http://arduino.cc/en/uploads/Main/ArduinoNanoManual23.pdf

I don't see a B2 fuse on either? Plus if a fuse blew it wouldn't have allowed 1.6 volts through, just +5v if good or 0 if opened.

There is however a "diode (D1 Diode, Schottky 0.5A 20V MBR0520LT1G" that might have been what you damaged and replaced?

Lefty

I pulled the same bone head move, shorted the 5v to ground.
And yes it does kill it. Looks like from the schematic that it is the MBR0520 diode that is now dead. >:(
If you connect external 5v power to VIN and GND everything still works.
Any idea why that diode is so touchy?

Thanks
Chris

Yep same stupid move lastnight! Thought my unit was toast.
Went a googling, and found this thread, sure enough if you supply 5VDC on the VCC pin this chip is fine and I can even program via USB but it just won't power off USB anymore.

Going to go look at the diode you guys are talking about and see if I can jump it or replace it, thanks a TON! Imense help!!!

And yes I'd say that diode is a tad touchy and needs a replacment product on v4

Yep that was EXACTLY it!
Pulled that Diode made a tiny jumper and my unit is back online via USB power like it never happened.
I may order another diode for it on my next order with Mouser, I just dont want to have to pay shipping for that dumb $0.20 part.

But for now I'm back in action, and I will try not to do anything stupid until I have that diode replaced.

Here is the pic of my repair for others that run into this issue...
PS: This is V3.0 Nano

Found the Diodes on Ebay: 25 of them for $2.70 shipped, out the door cost.
So if you need one contact me and I'd be glad to mail you one or two if you pay the $0.44 postage. I only needed 1 of them.

Here is my completed repair picture, the chip is working awesome and is once again protected from stupidity (To an extent) :slight_smile:

I have now purchased three nanos just so I can finish my project on time... I have stupidly short circuited two. My question is how do you check if the diode is dead?

Use the continuity tester of a DMM with the positive lead on the anode of the diode, and the negative lead on the cathode.

Was the diode a Schottky 0.5A 20V MBR0520LT1G??? I think I need to buy these!

Sorry to spam, but would a Schottky 1.0A 40V be an appropriate replacement?

Sorry it took so long to see this.
Here is the part on Ebay