COM port problem

Development Tools IDE 1.x
1

I am using the 1.0.5-r2 IDE on a Windows 7 computer.
My Arduino is a MEGA 2560.

It was working but with the occasional loss of the COM port. A disconnect and reconnect of the Arduino usually fixed it.

But now it has stopped completely. When I start the IDE the right COM port is not shown under Tools.
I reinstalled the driver and it worked until the next computer shutdown and restart.
So I reinstalled the driver again (C:\Program Files\Arduino\drivers) but it still would not work.

Now it comes up as an unknown device in Device Manager.

Any other things I can try?

(The Arduino works fine on my laptop, windows 8.)

Steve

2

Very weird.
How much current are you drawing from the USB port?

Sounds like the problem is the usb port, not the board.

3

Aha!
I had not considered the current drain.

I have made a light display using the Arduino, two Colorduinos and 128 RGB LEDs. I feed 5 volts into the Colorduinos from a power supply, then 5v on to Vin on the Arduino. It runs at more than 200mA and works fine.
But I am still expermenting with different programs on the Arduino using the USB connection. I have sometimes disconnected the 5 volts from the Colorduinos but left the USB connection. Then the Vin connection on the Arduino supplies 5v to the Colorduinos but their intensity is much lower. I assumed that the Arduino would limit its current from the USB port and it would do no harm. Perhaps somewhat foolishly!

I have done a System Restore to get my Arduino driver back.
And I have fitted a diode so current can go from the Colorduinos TO the Arduino board but not the other way.
I hope this will fix things.

Many thanks for your helpful post.

Steve