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I was working with an Arduino clone (Osep) controlling an electric pump, when I accidentally fried digital pin 9.  It read zero volts no matter what I did.  Since I needed to use PWM, I switched to pin 10 and continued on.  After I got everything working OK, I noticed the motor would start briefly during program upload, and also whenever I opened the serial monitor.  I tried a 10K resistor between pin 10 and ground, but it didn't change anything.  I was new enough to the Arduino that I just assumed this was normal behavior. 

Eventually I got tired of disconnecting the motor every time I wanted to use the serial monitor, so I started investigating.  I found there was .35 volts on pin 10 even when it was set to LOW!  Here's the strange part - the motor didn't run all the time (as one would expect) because this model has a brake functon that activates when the voltage is below .4 volts.

Moral:  When you burn out a pin, get out your voltmeter and check the other pins!  Happy troubleshooting!

Tom 
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Washington
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Likely there was thermal damage the partial melted the adjacent output FET inside the chip.
I think the moral is to avoid burning pins out.
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The moral is to not burn pins out?  I hope that was a joke.  We all make mistakes and hopefully learn from them.
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 We all make mistakes and hopefully learn from them.
Of course we do. And I have certainly blown things up. I have even had a voltage regulator on a Arduino board fail shorted and take out both the FTDI chip and the Atmega328 although I was not at fault as far as I know. It just "happened". It was an interesting learning experience replacing a SMD chip with substandard soldering equipment. It looks bad but it worked.

I have yet to blow up a micro-controller pin though (knock on wood).
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Avoid throwing electronics out as you or someone else might need them for parts or use.
Solid state rectifiers are the only REAL rectifiers.
Resistors for LEDS!

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I'd replace the chip. No telling what collateral damage may have occurred that could cause future failures.
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How was the motor connected to the pins?
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I'd replace the chip. No telling what collateral damage may have occurred that could cause future failures.

Sounds like good advice, but the chip on this Osep clone board is surface mount.  Replacing it would be too difficult for me.  Good news is the other pins seem to be fine so far.

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How was the motor connected to the pins?

The motor was connected to the board with 22 gauge jumpers.  Actually, it wasn't properly connected at the time of the accident.  I think I was trying to rewire something on my breadboard when the 24 VDC supply wire came loose and I was probably waving it around while trying to re-connect it.  The actual damage happeded suddenly - literally in a flash!
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You didn't connect the motor directly the arduino board (no transistor), did you?
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No, I didn't, but thanks for asking.  Sorry I misunderstood the question.  The pump motor I'm using has a control board with it, so I only need to supply a 0-5 volt signal to the control board in order to run the motor from zero to full speed.  In fact, being new to this sort of thing, I made sure the motor I bought came with a control board! 
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Next time, turn the power off before rewiring. It can prevent the smoke from coming out  smiley-grin
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Avoid throwing electronics out as you or someone else might need them for parts or use.
Solid state rectifiers are the only REAL rectifiers.
Resistors for LEDS!

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I have blown 1 chip while utilising Parallel Programmer and another accidentally inputting AC power into it and it just blasted and also DON FIREWORKS on the Breadboard while inputting high voltage on Low Voltage ranking caps.

I have learned a lot and in this Computer Science you learn a lot and you continue always its never ending ,You are learning even on the day you Die, its so much Deep.

Another thing, AC power never Forgives, if you are wrong! at your concept it makes sure it Punishes you!
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Next time, turn the power off before rewiring. It can prevent the smoke from coming out  smiley-grin

Good advice.  Maybe I'll do that when I have only a few good pins remaining  smiley-twist

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I have learned a lot and in this Computer Science you learn a lot and you continue always its never ending ,You are learning even on the day you Die, its so much Deep.

You are right, I have learned a ton since I bought an Arduino 2 months ago.  Much of what I learned was from YouTube and this forum.  The rest was from figuring it out on my own because I was afraid to ask a question on the forum!
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because I was afraid to ask a question on the forum!
You shouldn't be, I have never seen anyone put down for asking a "dum" question. In my book there is no such thing, if you don't know then you don't know.

There is however a dum way to ask a question, which is not the same thing. Like the people who ask what is wrong with their code without posting it.
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You shouldn't be, I have never seen anyone put down for asking a "dum" question. In my book there is no such thing, if you don't know then you don't know.

Thanks for the encouragement.  I think my perception of "put down" is probably different than yours.  The main thing was I didn't want someone to point out something that I could have worked out for myself.  So far I've been able to answer my own questions by looking it up on this forum (thank you all!) or performing some kind of test with the components or software.   
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