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Topic: [solved]Arduino nano 5.5V after diode replacement (Read 1 time) previous topic - next topic

prologikus

Oct 03, 2016, 08:06 pm Last Edit: Oct 04, 2016, 01:30 am by prologikus
Hi, i had an accident with my arduino witch burned the diode (0.5A, 20V), the nano still worked after that but it gives me 4.35V on main 5V pin,

After i replaced it with a new one, with the same id, the same pin, 5V gives me 5.5V (nothing connected)

Is there anything wrong ?

(New diode name: MBR0520L)

Edit: the battery from the multimeter(dmm) was low

CrossRoads

Maybe you need a new 5V regulator as well.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

prologikus

Maybe you need a new 5V regulator as well.
before i buy if, it is better to use the older diode ?

if i won't use the usb only for uploading, and use a step down convertor to power it but while i'll upload the code, because of the posible broken regulator, i can damage it?

CrossRoads

"if i won't use the usb only for uploading, and use a step down convertor to power it but while i'll upload the code, because of the posible broken regulator, i can damage it?"


If you use only one power source at a time, you may be okay, as long as:
Diode D1 and 5V regulator U3 on the Nano are not damaged.  If the FTDI chip U2 is damaged, USB will not work, and 3.3V may not be available.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

DrAzzy

#4
Oct 03, 2016, 09:54 pm Last Edit: Oct 03, 2016, 09:54 pm by DrAzzy
Were you powering it off USB (with nothing connected to Vin, I mean) when you measured the 5.5v? If so, that raises questions about your USB power supply. USB is supposed to be 5v nominal, 5.2 is common (to compensate for cable resistance when charging). There's no way a nano can generate a voltage higher than the input voltage, so if you're not powering from an external supply (which would lead one to question the regulator), and it's reading 5.5v, your USB power source is putting out a significantly higher voltage than it should and should be replaced.
ATTinyCore for x4/x5/x61/x7/x8/x41/1634/828/x313 megaTinyCore for the megaavr ATtinies - Board Manager:
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6v6gt

I guess that it is not worth spending too much time and effort to fix your old nano when you can get them at prices like this (clone) aliexpress nano

Wawa

Could also be that the DMM is not reading accurate.
I have a cheap DMM that reads the wrong voltage before the low-batt warning comes on.

On USB supply, the 5volt pin on a Nano will always be that diode drop (~0.4volt) lower. Never higher.
The diode is not used on external (V-in) supply.
Leo..

prologikus

Could also be that the DMM is not reading accurate.
I have a cheap DMM that reads the wrong voltage before the low-batt warning comes on.

On USB supply, the 5volt pin on a Nano will always be that diode drop (~0.4volt) lower. Never higher.
The diode is not used on external (V-in) supply.
Leo..
You was right, it was the multimeter, I replaced the battery and now It shows me ~4.7*

Thanks you all

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