I managed to run a sketch once and it seemed to kill my Uno.
It wont run the sketch anymore and although my computer and the Arduino software can recognise the board, it'll just hang during an upload.
Both 47uF capacitors behind the DC socket get very hot so it's hardware related.
I've swapped the ATmega chip but it's still the same.
Any ideas or is it dead?
It is likely the 47uF capacitors were fried by a voltage larger than the rated 15 volts. They will often short when their rating voltage is exceeded, and that causes them to heat up. I would not run your PC with the board attached for too long because it could damage your PC voltage supply.
If you are skilled at soldering, you could replace the 2 47 uF capacitors. Then, get a 9 volt battery and hook it up to the UNO power connector (+ and - correct) and use a volt meter to see if the 5 volt pin has the right voltage.
You might be lucky and the capacitors saved all the chips from being fried. If the new capacitors aren't getting hot, you might try running a quick to load program like blink to see if it works.
If the 5 volts is way off or the capacitors still are hot, I would toss the board and buy a new one. Costs much less than a new PC.
Good luck.
It was being powered by 12v when it stopped working, I've tested the power adapter and its working properly so I don't really understand how it happened.
I do agree that the capacitors are probably fried though, I do have a rework station to change them, I'm now wondering if its even worth the bother when I can just return it to Amazon and get a replacement.
Thanks for your help.
Hello,
It is practically impossible to make a sketch that causes physical damage to the Atmega in this way, if it is alone. Even something could be done with the EEPROM, but I believe that is not the case.
Did you have anything connected in your UNO when it got damaged?
When you replaced Atmega, did you make sure you left it in the correct position? Did you follow the marking on the side that is the first pin?
I realise it wasn't the code that damaged it but rather what the code instructed things to do.
I had a relay board connected up using the 5V, GND and 4 digital pins, 2 servos using 2 digital pins (powered by the same 12v for the Uno but in series so they each saw 6V), and the 3.3V pin connected up to one of a relay COMs. The other relays COMs all had 12v.
If there's anything that could be to blame, I'd probably say the 3.3v line drew too much current to power a motor but the motor was already in motion so I didn't think it would have the inital high current draw usually required.
Yeh, the ATmega was replaced correctly, I know to look for markings etc for orientation.
COM is also shortform for COMMON / GROUND.
I would say putting 3.3 volts there instead of a ground was a a conflict between 3.3 volts and the 5 volts and a sure fire method of destruction.
Just putting things in series is also no measure of getting things to use half of the previous components voltage without making 100% sure with test equipment.
Even then there is CURRENT to take into account.
Not being disrespectful here but so many things could have gone wrong with how you had things connected.
A basic primer in electronics might be of use.
All noted.
Had no idea what COM meant tbh, I just know its the middle contact between NO and NC, does it actually matter if the current flows from COM? Its just a switch after all.
I don't understand where the conflict comes from though, the 5V is for the relay coil which is isolated from the contacts.
Both servos are exactly the same so I don't see an issue with a series connection to half their voltage, current draw would have been fine with the power adapter I'm using.
It can also be a COMMON VOLTAGE, COMMON BUS and a few other variations. In this case doubtful to be the actual issue as now we know its is the common between NC and NO but I would still get to grips with a few more basics.
A half decent schematic would probably benefit us all here even hand drawn.
