RAMPS disconnects when I unplug the USB

I had my printer working fine and I made a silly mistake when tired.
I plugged one of the limit micro switches in across the positive and negative pins instead of the signal pin.
A puff of smoke. Can't see any damage anywhere on the board and the diode seems to be OK.
The printer will work fine in everyway, except now when I disconnect the USB the printer will reset and power down loosing all that has been printed.
I normally run off the LCD controller and don't have the computer connected. It looks like I now need power from the USB in order for the electronics to work.
Anyone got any ideas what I have blown (if anything) or how to fix the problem?

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

you have fried the voltage regulator on the mega2560 board, without this your mega needs to be plugged into USB for power

See [www.instructables.com] for how to fix it (I dont recommend replacing with 7805, but it does show you the parts to look at and what they were

Edited 2 time(s). Last edit at 10/17/2014 01:45AM by Dust.

Quote
Dust
you have fried the voltage regulator on the mega2560 board, without this your mega needs to be plugged into USB for power

See [www.instructables.com] for how to fix it (I dont recommend replacing with 7805, but it does show you the parts to look at and what they were

Thanks for that info, I will check it out.

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci