Original Uno and Nano clone Vin not working

Other Hardware 3rd Party Boards
1

I am trying to power them with a 9v battery for a project but when I connect the negative to GND and positive to Vin, it does not power up as the ON LED does not light, I confirmed the arduinos work after and before attempting to connect the 9v and also checked the 9v output with a multimeter which reads 9.3v. I powered each arduino individually with the 9v without anything connected to its GPIO

This is the way I used the 9v to power the arduinos, do not question because I didn't have any spare 9v clips and no shops sell them nearby, also amazon delivery dates were a bit too long.

image
image1200×1600 283 KB

Below are the pictures of my UNO

image
image1200×1600 166 KB

image
image1200×1600 122 KB

The barrel Jack of the Uno works fine but the output on the 3.3v is 0v so it seems the 3v3 regulator is dead. The Uno runs all code normally so I didn't notice until now and the 5v output is at about 4.3v ( but it starts at 2.3v and fluctuates between 2v and 3v for 2 secs then reaches 5v it seems)

Pics of Nano clone

image
image1200×1600 133 KB

image
image1200×1600 146 KB

This nano uses a CH340 driver with the Old bootloader option in the IDE, everything else works including the ICSP and the 5v output which shows about 4.6v

2

You MUST check the voltage while the battery is connected to the Arduino, not with an open circuit.

3

Yes the 3V3 regulator on a Uno R3 is only rated at 150mA, and due to the small PCB heat sink, the actual amount of current is less than this.

However, this chip has a thermal shutdown circuit and from your description:-

Suggests something else is wrong with your board as well.

This could be a capacitor going bad causing excessive current in the circuit and triggering the thermal shutdown in the 3V3 regulator.

This could have been caused by trying to power something, like a transmitter, that takes too much current in the past.

As to the nano clone then due to the possibility that to cut costs the quality of components were downgraded then all bets are off.

1 Like
4

I did what you said, i got the same reading

5

i did attempt to use a Nrf24 with the uno in the past using the 3v3 once, now i use the 5v adapters

6

However, this chip has a thermal shutdown circuit

Is it required for Vin to work and is it possible for it to be reset ?

7

Yes just turn off the power and re apply it again.

That is enough to screw things up because of the peak power that chip can demand.

8

Wouldn't that be equivalent to unplugging and plugging in the USB as there is no other power source?

If it is then I already did that but the output still shows 0v ( its actually 0.032v but i dont think that matters much>)

9

Yes.

Yes but what happens on the transients when you power it up? You need an oscilloscope to monitor the 3V3 output to see if it is going into thermal shut down.

Either way your hardware is screwed and needs replacing if you want to restore the 3V3 output.

10

lol, an oscilloscope is something I can't afford yet, and I also don't need 3v3 output for now. But does the 3v3 regulator affect Vin's functionality?

11

Yes it could do as it might play a part in the dance the 5V appears to do.

You could try removing the 3v3 regulator if your soldering skills are up to it.

12

I don't think ill be able to do that as i only have one iron older than me with 10 year old solder and flux, any alternatives you know of?

13

Only cutting the traces to the chip with a scalpel.

My soldering iron is about 50 years old now.

14

That's older than mine, though I don't do any cleaning on my iron.

I don't want to potentially damage anything on my board or do something I can't fix with my current skill. Is it possible to use a Male USB power regulator or something?

15

You can power your board over USB. USB charger, power bank; the latter does not always work.

You can also use three 1.5V batteries connected to the 5V pin, but with your 5V problems (when using Vin) that might not now no longer work.

1 Like
16

thanks for letting me know, ill see what i can use for this project, thanks

17

Fault finding starts with eliminating things.

Connect your board to your computer, if it still acts weird, it’s got nothing to do with the battery. If it works fine , it’s the regulator or something with the battery (loose connection?).

Then go from there, further eliminating things.

An Arduino board can work off VIN power or USB power. If both are present, the board uses VIN power.

A regulator that goes in thermal shut down will resume when cooled down, unless really damaged.

18

the battery connections aren't loose as they are soldered jumpers which plug into the uno, and the board works normally with usb power.

For the thermal shutdown part, nothing is heating up now on the board but 3v still has no output so i guess the 3v3 reg is dead?

19

That is what I would think.

20

When powered from VIN or from USB?