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[on:]

Hey guys,
I have a huge problem, I hopoe you can solve it to me!
So it goes like this:
First of all, my board model is UNO R3.
I connected 5V from 7805 to the 5V on the Arduino, of course the USB cable was disconnected when I did it.
After I did this, my computer hadn't recognized my Arduino and when I press on the reset butten it doesn't respond anymore.
I've tried to change the outcoming electronic component with 20 legs, which is called "ATMEGA328P-PU DIP-20 Microcontroller" see it in the link below:
http://www.ebay.com/itm/300726927158?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

Just one things has changed: the L light in now flickering, the older ATMEGA328P makes the L light just turn on.
In both cases restart can't be done on this Arduino.

Someone sent me these solutions but I misunderstood it, does anybody know if this solution works and can fix my Arduino?
I'll be glad to get some explanations how to do it exactly if it works 100%.
http://arduino.cc/en/Hacking/DFUProgramming8U2
http://blog.ethanfrei.com/2011/10/arduino-uno-revived.html

Thank you.
I'm looking forwade to your solutions,
Kobi.

[Reply #1 on:]

Does the board work if just plugged into USB with no other external power or other things attached to it?

If not you must have damaged the board somehow when you applied the external +5vdc to the 5V pin. If you have a multimeter you might try measuring the voltage at the 5V pin to see what it reads when just attached to to the USB.

Lefty

[Reply #2 on:]

Does the board work if just plugged into USB with no other external power or other things attached to it?

If not you must have damaged the board somehow when you applied the external +5vdc to the 5V pin. If you have a multimeter you might try measuring the voltage at the 5V pin to see what it reads when just attached to to the USB.

Lefty

Hey,
yes, the board works when I connect it just to USB cable, but the computer doesn't read it.
I tested my board as you said and the results are:
The 5V output gives me 4.3V which is OK.
The 7805 of the Arduino gives me the same Voltage, on the middle leg I get 4.3V and on the left leg I get 3.8V.

[Reply #3 on:]

outcoming electronic component with 20 legs, which is called "ATMEGA328P-PU DIP-20 Microcontroller"

the 328p-pu has 28 legs. count em...

The 7805 of the Arduino...

a 7805 is not a standard part for the Uno, your wiring is not very clear in your description. Are you referring to the arduino's on-board regulator or an external component? If the onboard regulator, then it is irrelevant because you are powering the uno from USB. The v. reg. and USB are two seperate power sources.

 The middle leg (pin #2) of a 78xx is ground (0v), the left leg (pin#1) is input ( you never mentioned what the voltage is of your external power source you are using), and the right leg (pin #3) is output (5v). If this statement-

... gives me the same Voltage, on the middle leg I get 4.3V and on the left leg I get 3.8V.

- is true, then something is either wrong with how you measured it or the 7805 is damaged or incorrectly wired.

Wiring and description aside, you might try a loop back test (http://arduino.cc/forum/index.php/topic,73748.0.html) to see if the usb-to-serial chip is damaged.

[Reply #4 on:]

Just a shot in the dark, but I had a problem even getting my Mega R3 board to work with
the Arduino IDE in the first place. I couldn't find any info anywheres at all about this, except
on the following thread, which gave a procedure that allowed me to install the proper driver
for the R3 USB chip. Non-intuitive. Maybe you have the same problem.

http://arduino.cc/forum/index.php/topic,133030.0.html

[Reply #5 on:]

The 5V output gives me 4.3V which is OK.

Says who?

It should be 5V ... 4.3V is a huge error and indicates the power circuitry is probably blown.

[Reply #6 on:]

outcoming electronic component with 20 legs, which is called "ATMEGA328P-PU DIP-20 Microcontroller"

the 328p-pu has 28 legs. count em...

The 7805 of the Arduino...

a 7805 is not a standard part for the Uno, your wiring is not very clear in your description. Are you referring to the arduino's on-board regulator or an external component? If the onboard regulator, then it is irrelevant because you are powering the uno from USB. The v. reg. and USB are two seperate power sources.

 The middle leg (pin #2) of a 78xx is ground (0v), the left leg (pin#1) is input ( you never mentioned what the voltage is of your external power source you are using), and the right leg (pin #3) is output (5v). If this statement-

... gives me the same Voltage, on the middle leg I get 4.3V and on the left leg I get 3.8V.

- is true, then something is either wrong with how you measured it or the 7805 is damaged or incorrectly wired.

Wiring and description aside, you might try a loop back test (http://arduino.cc/forum/index.php/topic,73748.0.html) to see if the usb-to-serial chip is damaged.

Hey,
I tried doing it but unfortunately my computer doesn't recognize the Arduino...
What should I do?

The 5V output gives me 4.3V which is OK.

Says who?

It should be 5V ... 4.3V is a huge error and indicates the power circuitry is probably blown.

Ok, so what should I do to fix it?

Just a shot in the dark, but I had a problem even getting my Mega R3 board to work with
the Arduino IDE in the first place. I couldn't find any info anywheres at all about this, except
on the following thread, which gave a procedure that allowed me to install the proper driver
for the R3 USB chip. Non-intuitive. Maybe you have the same problem.

http://arduino.cc/forum/index.php/topic,133030.0.html

Sorry but what you describe here is not my problem.
Thank you.

[Reply #7 on:]

I connected 5V from 7805 to the 5V on the Arduino

Why would you do this? The Arduino has it's own 5V v.reg.

First off, I would disconnect anything connected to the Arduino headers. Then if you're still
measuring only 4.3V on the 5V rail, with either USB or power to the Power Jack [assuming
you have an adequate external supply], it sounds like you have damaged the v.reg, or less
likely some other parts on the board. Short of knowing how to go through and troubleshoot
every part, sounds like time to buy a new one. [we all do it].

[Reply #8 on:]

I connected 5V from 7805 to the 5V on the Arduino

Why would you do this? The Arduino has it's own 5V v.reg.

First off, I would disconnect anything connected to the Arduino headers. Then if you're still
measuring only 4.3V on the 5V rail, with either USB or power to the Power Jack [assuming
you have an adequate external supply], it sounds like you have damaged the v.reg, or less
likely some other parts on the board. Short of knowing how to go through and troubleshoot
every part, sounds like time to buy a new one. [we all do it].

I'm not gonna buy a new one, this one is enough to me...
Can I fix it independently?

[Reply #9 on:]

I've been doing electronics for many years, but trying to troubleshoot a board
with a bunch of tiny tiny surface mount devices is probably more trouble than
I'd like to go through myself [for a $30 board].

[Reply #10 on:]

Power the arduino (just the arduino, remove everything else that might be plugged into it) by connecting an external source(7-12v) to the barrel jack. Does it turn on? If it does, what is the voltage at the 5v pin? 

I tried doing it but unfortunately my computer doesn't recognize the Arduino...

make sure you have the right drivers installed. You may even try reinstalling the IDE software all-together. If that doesn't work, look into DFU mode for the USB chip. You might try simply resetting it before re-uploading the firmware.

[Reply #11 on:]

Did you install the driver for it on the computer to recognize the arduino?

[Reply #12 on:]

I've been doing electronics for many years, but trying to troubleshoot a board
with a bunch of tiny tiny surface mount devices is probably more trouble than
I'd like to go through myself [for a $30 board].

Look, the price of this little board in Israel (where I live) is very expensive compared to the price in USA or other countries.
For me it's worth to fix it, and I appreciate the money even if it's 10$ board, I'll do anything to fix this.
This is my attitude to this and I see that yours is totally opposite.
If you don't want to help for 30$ board, I don't make you doing it...
Thank you anyway.

Power the arduino (just the arduino, remove everything else that might be plugged into it) by connecting an external source(7-12v) to the barrel jack. Does it turn on? If it does, what is the voltage at the 5v pin? 

I tried doing it but unfortunately my computer doesn't recognize the Arduino...

make sure you have the right drivers installed. You may even try reinstalling the IDE software all-together. If that doesn't work, look into DFU mode for the USB chip. You might try simply resetting it before re-uploading the firmware.

I turn the board on by connectiong into Vin input 5V fron 7805 from another board.
I do have the right drivers, you ,misunderstood that it was working till I did the huge mistake of connecting 5V from 7805 to 5V output on the Arduino board.
Do you have any idea fixing it?
I love your idea of DFU mode, please guide me how to do it.

Did you install the driver for it on the computer to recognize the arduino?

Yes, I did. Everything went great untill I connect 5V from 7805 from another board to 5V input on the Arduino to turn it on.
Since that accident my computer can't recognize my Arduino.
Do you have the solution?

[Reply #13 on:]

I turn the board on by connecting into Vin input 5V fron 7805 from another board.

This does nothing for trying to see if the onboard regulator is functional, and does not answer my questions:
 (#1)what is the voltage at the 5v pin?  
Now, if you do not have a 2.1mm plug that's a different issue, but (#2) what are you powering the 7805 with, and (#3) what is the measured voltage output of the 7805?

5V from 7805 from another board to 5V input

If everything is connected properly and operating normally, this shouldn't have caused a problem. You can feed 5v (from a well-regulated source) directly to the 5volt rail, I do it all the time.

Do you have any idea fixing it?

Google does...  "Arduino DFU mode"

[Reply #14 on:]

I turn the board on by connecting into Vin input 5V fron 7805 from another board.

This does nothing for trying to see if the onboard regulator is functional, and does not answer my questions:
 (#1)what is the voltage at the 5v pin?  4.2v
Now, if you do not have a 2.1mm plug that's a different issue, but (#2) what are you powering the 7805 with? 12v ADAPTER and (#3) what is the measured voltage output of the 7805? 5v

5V from 7805 from another board to 5V input

If everything is connected properly and operating normally, this shouldn't have caused a problem. You can feed 5v (from a well-regulated source) directly to the 5volt rail, I do it all the time.

Do you have any idea fixing it?

Google does...  "Arduino DFU mode"

OK