I am using an Arduino Mega 2560 and have tested it on multiple computers with multiple different USB connectors. The Arduino powers up when it is plugged in, but the port option under Tools is grayed out. After reading many of the forum postings, I tried installing the proper driver only to find that the device is not appearing under the Device Manager tab on any computer I try this on. The board was used with an actuator that provided a high current output, which gave indication that it may be fried. However, if that were the case, why would the board still power up when plugged in? Please help.
Damage to the board does not take out every part on the board.
On official boards (and clones that use 16u2), the most likely part to be damaged is the 16u2 used as serial adapter. CH340G based boards tend to be harder to damage in this way.
On all boards, the opamp that buffers pin 13 and controls the janky power switching circuit is also very easy to damage, one symptom of this is that the pin13 led will be stuck on.
What makes you say it powers up? The power LED is just an LED and resistor across the power rail - that only tells you that the board is getting power, says nothing about the state of any other parts on the board. It would take an impressive amount of abuse to make the power LED not come on.
Thank you for your help.
The power light turns on, and the pin 13 LED blinks when it is plugged in or reset. These are the only signal the board is outputting, as the board will not connect to the computer. Due to the lack of outputs it is providing, the lights were the only determination I had to tell if the board is getting powered.
Huh, since the pin13 LED can blink, that implies that both the microcontroller itself, and the opamp are both fine, which argues against electrical abuse trashing the board.
What serial adapter chip does it use (check the markings on the black IC near the USB connector)? If it's a 16u2, it's definitely possible to trash that while leaving the opamp and everything else intact. The 16u2 is sort of notorious for being easy to damage from abuse of the power rails, including the spikes that inductive loads generate if you don't take the standard precautions and sometimes from a sequence of events involving external power sources that doesn't sound like it should cause any problems. If it's a CH340G, it surprises me that you managed to trash it without blowing the opamp, but I suppose is possible. Do other boards with the same serial chip work on that PC?
That's why, with sadness, I recommend new arduino people to use CH340G clones rather than official or 16u2 clones - they're harder to trash making newbie mistakes. I use almost all clone and own-built boards, and periodically donate to Arduino to make up the karma (though one might argue that with all the projects I maintain and help I give here, I probably don't owe arduino any karma)