Ramps 1.4 Arduino Mega fried HELP ME FIND WHY (Is not voltage regulator )

So I was calibrating the stepper drivers on my Ramps 1.4 board when I touched the stepper driver with my screwdriver by mistake, That melted my Stepper motor connector and fried the voyage regulator (I tested it, making ),making the LCD contrast weird and the SD reader not working. So I disconnected the D1 diode and I connected 5V from my power supply to the VCC pin on Ramps in order to avoid using the bad voltage regulator , and It worked perfect again, the SD, the LCD and USB connection with Cura. So I replaced the melted connector on my stepper motor and put a new stepper driver. But when I turned the printer on, the LCD showed something weird, there was a loud buzzing sound and something smelling burnt, So I disconnect the stepper motor and driver, Turned it on again and nothing showed on the display. I separated the Arduino to test it , and It doesn't turn on by USB. I could get a new one very cheap but I dont know if my Ramps is bad and will damage it again. Thank you

Unfortunately there is no protection on the mega for someone applying 5v to VCC and plugging in usb 5v (there is if you use vin and usb, it safely selects Vin over usb)

So the two 5v's will battle it out since they are most likely not identical 5v. till one of them wins...

I would guess you have fried your usb port power...

Have you got a usb power meter ? check its still putting out 5v ?

Also a lot of USB chips have protection in them, but you have to completely power off for a while (including removing batteries in laptops)

Try a different usb port.

If it still doent work... mega has an issue
5v on usb goes through a fuse then a mosfet then into the atmel 2560 mega. With a multi meter check 5v is on a 5v pin of the mega when plugged into usb.
if its not there check the fuse (pictured below)
If it has 5v and still isnt running... time for a new mega



Edited 1 time(s). Last edit at 08/15/2018 02:41PM by Dust.