I also have a problem with my MEGA
even in device manager i can't see my arduino mega
no sound created when i connect it to my laptop
im pretty sure my cable is working because i can still upload code to another arduino using it.
i tried to use other laptops but still didn't work
hope some one could offer some help pls.
Topic split. (currently you were in HIJACK mode)
Also a few more details.
Specific OS ?
Type of USB ports used ?
Version of the IDE being used ?
im using windows 10 64-bit
i already tried using different usb ports usb 2.0 and 3.0 buy still didn't work
i'm using the current/latest version of ide
i tried re installing
actually i also have this problem with my another arduino uno
i tried to code it using arduino as isp and used another arduino uno to upload as programmer but didn't work i always got some error messages..
i found out that my arduino mega (broken no serial port detected) uses atmega16u2 the same with my another arduino uno which is also broken like no serial port detected even unknown device didn't appear.
i only have one working arduino which uses ch340
i think atmega16u2 has somerhing wrong going on...
whats hijack mode by the way...
you mean manufacturers are cheating?
HIJACK Means you were jumping on somebody else issue without due consideration or understanding of the problem at hand.
In you case you have added that it seems limited to the 16u2.
Yes they are often more fragile than the CH340 and do seem to fail if "abused" in any way.
When they go the board can often still be used but just not with the USB port availability.
That's where the ICSP comes in useful.
Whilst easy enough to use another Arduino my own preference is to use a dedicated ICSP device
Super cheap in Ebay
Heads up. Duplicate posts are also frowned upon.
Your other post DELETED.
Please do take a little time to READ THIS
It could save you some grief later. 
can i replace the atmega16u2? with a new one?
Do you have SMD rework experience and facilities ?
Are you prepared to chase other possible damaged items through the board ?
If the answer to either of them is NO then you have your answer.
I dont and cant so if I pop anything like that then its usually a matter of "is there anything I can salvage ?" if not its into the PCB bin with it.
At that point I take stock of what I probably did wrong and vow never to do it again.
The other thing to beware of with REAL arduinos is they say they can handle a larger voltage than they often really can.
If I use an external voltage to power a MEGA or UNO I always keep it below 10 volts even though the specs say it can take more. Since taking that approach I havent blown an arduino.
when i connect my arduino mega 2560 to my laptop - no sound is created. i can't see it in the device manager. i can't even see unknown devices or etc when it is connected to pc.
i know my usb cable is working because it works on other arduinos.
here are the things i tried:
-use another usb cable
-tried to use the usb ports 2.0 and 3.0
-re installing ide
-restarting my laptop while pc is connected
- tried to look for hardware changes in device manager multiple times.
i tried to search about this but the threads i'm directing into is somewhat their arduinos are detected as uknown device but mine is not..
hope someone could give me a help
DON'T CROSS POST!!!!!!!!!!!!!!!!!!!!
http://forum.arduino.cc/index.php?topic=577182
I HAVE REPORTED THIS THREAD TO THE MODERATORS
Duplicate posts waste the time of the people helping you. I might spend 15 minutes writing a detailed answer on this thread, without knowing that someone already did the same in the other thread. This behavior is very disrespectful to the people you're asking for assistance. Just because we give our time freely doesn't mean it has no value.
You were already warned once before not to do this:
http://forum.arduino.cc/index.php?topic=577182.msg3929900#msg3929900
In the future, take some time to pick the forum section that best suits the topic of your question and then only post once to that forum section. This is basic forum etiquette, which you would already know if you had bothered reading the sticky "How to use this forum - please read." post you will find at the top of every forum section. It contains a lot of other useful information. Please read it.
Threads merged.
johnwill25:
can i replace the atmega16u2? with a new one?
A good place to start would be to reflash the firmware on it.
the last code i uploaded to it i used serial communication to check wether i'm having the right output.
Now when i want to power arduino using power jack i forget to delete the serial.begin part in the code...
maybe it's the reason my atmega16u2 gets corrupted. what do you think with my guess? am i right or wrong?
By the way i tried to use another arduino as a programmer to my arduino mega but it always fail
johnwill25:
maybe it's the reason my atmega16u2 gets corrupted. what do you think with my guess? am i right or wrong?
Wrong. That wouldn't corrupt the ATmega16U2.
johnwill25:
By the way i tried to use another arduino as a programmer to my arduino mega but it always fail
When you encounter an error you'll see a button on the right side of the orange bar "Copy error messages". Click that button. Paste the error in a message here USING CODE TAGS (</> button on the toolbar).
what might be a reason of a corrupted atmega16u2?
Over-voltage to components.
Reversed polarity to components.
Connection to non compliant devices.
Setting board on conductive surfaces.
Incorrect insertion of shield type devices.
The list is quite large to be honest but those cover some of the more common issues seen.
It takes only a fraction of a second to let magic smoke out of devices and after than its pretty much game over most of the time.
Slippery electrickery !
i sometimes see that my arduino's 5v is outputting (don't know if that's a right term) more than 5 volts usually it's around 6v.
is it also possible that the atmega 2560 microcontoller is destroyed but the atmega 16u2 is not?
if so? can i still see it's serial port when connected to my laptop
If the 16u2 is dead chances of seeing a serial port of any kind are slim to none.
The work around for that is to use a SERIAL UART or ICSP device to bypass the 16u2 and talk directly to the 2560.
If that works then the 2560 can still often be viable.
if not just consign it to scrap.