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Topic: VIn-Pin wrong polarity - Repair?! (Read 2025 times) previous topic - next topic

Kelevra86

Hello everyone,

i own a Arduino Mega 2560. Unfortunately i applied 7.2V/DC with the wrong polarity to my VIn-Pins. It fumes a little bit and now it´s no longer working -.-
This part fumed.
http://imageshack.us/photo/my-images/36/arduinopx.jpg/
What is this part?
Is there a chance to repair it?

Greetings K86

johnwasser

That's the 5V regulator.  Does the board still work if you power it from USB?  If not you probably fried other chips.
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SurferTim

That should be about the easiest component on the board to replace. As a matter of fact, that is the culprit in another thread that I vented on this morning. If you replace it, I would do a Frankenstein on it. Use a "Lincoln Log" regulator, like a LM7805. I believe it is pin compatible with the smt unit that is currently there. Then you could use a small heat sink and use it with automotive voltage levels.

I would go with johnwasser's check. Does it power up and work with usb power?

Kelevra86

Ah interesting. Will test USB asap.
Could this replace the original part?
http://www.protostack.com/semiconductors/l7805-5v-linear-voltage-regulator

Greetings K86

wilykat

Yes it will work.

You may need to bend the pins a bit to fit in narrower solder pads

Kelevra86

Nice.
But for much ouput current? 1A, 2A, 3A? ...

michael_x

from your own link:
Quote
If adequate heat sinking is provided, they can deliver over 1 A output current.


500mA ( like the USB supply ) should be fine...

Kelevra86

#7
Sep 06, 2012, 02:41 pm Last Edit: Sep 06, 2012, 02:43 pm by Kelevra86 Reason: 1
Great.
Thank you buddys :)

EDIT:
USB connection still works. Probably it´s the 5V regulator.

cjdelphi

I accidentally reversed the polarity on a lilypad same atmega on the uno and others not the mega version..

the atnega smoked ! Once it cooled down it worked again.. :)

harrievandalen

This is Harrie and I blew the processor of my Atmega 2560. I removed the controller and replaced it with a new one. It does not work, so I first thought there might not be a bootloader inside, but I checked and also the clock is not running. Can anybody help me out?

Harrie

hugo007

Quote
but I checked and also the clock is not running

How did you test this? Osciloscope?
Did you test the power on atmega pins?
Did you solder it well?
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MarkT


This is Harrie and I blew the processor of my Atmega 2560. I removed the controller and replaced it with a new one. It does not work, so I first thought there might not be a bootloader inside, but I checked and also the clock is not running. Can anybody help me out?

Harrie


Impressive SMT skills!  If you didn't program a bootloader onto the replacement chip it won't have one.  You need to use the ICSP header and some programmer (or another Arduino) to try programming the 2560.

I think the AVR default fuses use the internal clock so you wouldn't expect to see the xtal oscillator running till it was first programmed - but could be wrong, anyone know for definite?
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floresta

Quote
I think the AVR default fuses use the internal clock so you wouldn't expect to see the xtal oscillator running till it was first programmed - but could be wrong, anyone know for definite?


You are correct.
9.3.1       Default Clock Source
                            The device is shipped with internal RC oscillator at 8.0 MHz and with the fuse CKDIV8 pro-
                            grammed, resulting in 1.0 MHz system clock. The startup time is set to maximum and time-out
                            period enabled. (CKSEL = "0010", SUT = "10", CKDIV8 = "0"). The default setting ensures that
                            all users can make their desired clock source setting using any available programming interface.


Don

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