I have quite a number of broken Arduino nano boards (^^" my fault, shorting 5V to ground accidentally), and I am guessing they have their voltage regulator fried.
They still work to a limited extend, i.e. if I power them via VIN with an external 5V power supply, they are just fine (USB upload sketch, serial communication with computer, functional on its own with battery, ...).
And, without an external 5V power supply, they are virtually dead.
Here are the questions. Are they going to further deteriorate? What am I risking if I keep on using them? In particular, without a voltage regulator to regulate the voltage, when the voltage fluctuation become too big a problem to ignore?
Well..... if they still work, then just keep using them. They'll likely keep working. So, instead of using the on-board regulator.... you just put in your own regulated voltage....the way you're doing now.
The external 5V supply you're using is likely to be a 'regulated' 5V supply. And that's fine. It's regulated.
You can also replace the regulator (if needed) to restore the arduino to its full glory.
ma_hty:
..if I power them via VIN with an external 5V power supply, they are just fine
Here are the questions. Are they going to further deteriorate? What am I risking if I keep on using them? In particular, without a voltage regulator to regulate the voltage, when the voltage fluctuation become too big a problem to ignore?
V-in is the input of the onboard 5volt regulator.
V-in should normally be >= 7volt for the onboard regulator to make a stable 5volt for the board.
If you connect 5volt to V-in, there is/should be less than 5volt in the 5volt pin. Measure it.
Connect 6volt (e.g. 4 AA batteries) to V-in, and measure the 5volt pin.
If you have 4.5 to 5volt there, then the 5volt regulator is probably ok.
Then try with a 9volt battery. You should now have a solid 5volt on the 5volt pin.
if the regulator works as it should, and the Nano doesn't work on USB, then you probably have blown the USB backflow diode. A small smd schottky diode. D1 on the diagram.
No problem to use the Nano with >=7volt on V-in (if the regulator is ok).
Or with 5volt on the 5volt pin (if the regulator is blown).
Leo..
Wawa:
... 2) if the regulator works as it should, and the Nano doesn't work on USB, then you probably have blown the USB backflow diode. A small smd schottky diode. D1 on the diagram. ...
Opps... it really was the diode D1 fried. After I replace D1, the USB power became functional again. Thanks.