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Topic: Accidentally applied 12VDC input to the 5VDC output pin... (Read 5211 times) previous topic - next topic

Dangerzone812

Hi all!

I wasn't exactly sure what the proper board would be for this "problem".

Long story short, I'm using my Arduino Mega 2560 to control several motors for a robot. The motors run off of 12VDC and I'm using an H-Bridge IC (http://www.ti.com/lit/ds/symlink/sn754410.pdf) to control the motors.

I accidentally miss-wired one of the pins for the circuit to the 5VDC pins from the arduino and had the 12 VDC source I was using applied to it. I heard a popping sound and instantly shut off all voltage.

I unplugged the board and now I'm trying to replug it in and just reflash it and now it won't pick it up in my device manager and I'm getting worried...The board lights up meaning it's powered...just not sure how the USB circuitry is now.

HELP!?

Grumpy_Mike

Sorry I would put money on you having screwed the whole thing. Putting 12V on to the supply should fry both the USB / serial chip and the ATmega itself.
Better order another board.

Quote
The board lights up meaning it's powered

No it just means the LED is lit.

oric_dan

"popping sound" - very cool, dead giveaway.

Yep, sounds like the entire board is toast. You did probably the one thing guaranteed
to cook everything. Been there, done that, we've all done it. You'll be less likely to
fry the next one now, :-). [don't buy a motorcycle].

john1993

maybe consider one with socketed mcu next instead of smd. and separate usb/serial cable is very smart too. much lower initial cost for both even with a handful of spare chips from digikey added on.

retrolefty

Well I once applied -12vdc to an analog input pin on a breadboard mounted 644p chip. Saw a quick flash and heard a sharp quick crack sound. However the chip continued to function minus that pin and the next three adjacent analog input pins. So it's not always easy to say just what damage such a 'brainfart' might do. However if the PC does not see the the USB connection when plugging the board in that means the USB serial converter chip went to go where chips go to die most likely.

Lefty

Grumpy_Mike

Quote
went to go where chips go to die

That will be silicon heaven then.

jonisonvespa

if your as tight as me id order a new chip, make sure it comes with a bootloader already installed 

at if it doesnt work at least you have a spare, or if you feel brave make a bare bones board yourself

(i do have 4 168 new blank chips for sale, no bootloader installed if anybody wants them ok only)

oric_dan

Quote
went to go where chips go to die

That will be silicon heaven then.


That place is only where all "good" chips go to die.

retrolefty


Quote
went to go where chips go to die

That will be silicon heaven then.


That place is only where all "good" chips go to die.


Yep, the 'bad' chips I've worked with and destroyed went into a trash can.

Does anyone remember working with the first early cmos logic chips? If you ended up in your design not using all the gates on a given cmos logic chip and forgot to wire all their unused input pins to Vcc or ground, they would burn up the chip due to device oscillation. I learned that by pressing my thumb onto one to see if cmos chips did indeed run much cooler then the 7400 series of TTL chips of the same era. A nice painful blister went with that lesson learned and not forgotten.

Lefty

Grumpy_Mike


if your as tight as me id order a new chip, make sure it comes with a bootloader already installed 

at if it doesnt work at least you have a spare, or if you feel brave make a bare bones board yourself

(i do have 4 168 new blank chips for sale, no bootloader installed if anybody wants them ok only)

Yes But if you read the first post you will see the OP has a Mega, so chip replacement is not much of an option.

oric_dan

Yeah, given my own track record with electronics, I ALWAYS opt out for boards
with socketed chips. [oft hand, I'll bet I have everyone else beat by 100,000X or
so, having once burned up a $7M space craft].

retrolefty


Yeah, given my own track record with electronics, I ALWAYS opt out for boards
with socketed chips. [oft hand, I'll bet I have everyone else beat by 100,000X or
so, having once burned up a $7M space craft].


That is begging for a 'now for the rest of the story' posting.  ;)

Lefty

oric_dan

The proper response would have been ... "So, you're the one".

I was young and foolish, and on drugs - namely antihistamines - and lost my way.
In the end, they only changed out a few boxes. 12V boxes don't like 40V, any more
than Arduino 5V rail likes 12V. I think they stopped using large size adjustable power
supplies after that.

jonisonvespa



if your as tight as me id order a new chip, make sure it comes with a bootloader already installed 

at if it doesnt work at least you have a spare, or if you feel brave make a bare bones board yourself

(i do have 4 168 new blank chips for sale, no bootloader installed if anybody wants them ok only)

Yes But if you read the first post you will see the OP has a Mega, so chip replacement is not much of an option.


opps didnt see that, wast just testing to see if anybody was cleaver enough to spot that thought it was an uno, :)

personally i would have changed the ic used to hand solder lots of 200 pin sm ics heatgun/flux/tweesers easy peasy.

jonisonvespa

#14
Dec 02, 2012, 02:01 pm Last Edit: Dec 02, 2012, 02:27 pm by jonisonvespa Reason: 1


Yeah, given my own track record with electronics, I ALWAYS opt out for boards
with socketed chips. [oft hand, I'll bet I have everyone else beat by 100,000X or
so, having once burned up a $7M space craft].


That is begging for a 'now for the rest of the story' posting.  ;)

Lefty


yup i second please finish the story we wont let this go :)  i which one was it? 7m sounds very cheep?

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