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Fried Arduino Mega What do I do?

Posted by plloppii 
Fried Arduino Mega What do I do?
June 22, 2017 10:39AM
Hi Everyone,

Today I tried to mount my ramps and arduino board onto my new control box. I screwed in two short m3 nuts to hold the board down. After I turned on the power supply I saw magic smoke. It smelled really really bad.
I unplugged everything and took off the ramps board. I saw that my voltage regulator on my arduino mega was fried. Do I just have to replace the mega? Or do I have to replace everything?

I connected the ramps to the arduino and powered the ramps board. Then I checked the voltage across the D8, D9 and D10 pins and they were all zero.

Re: Fried Arduino Mega What do I do?
June 22, 2017 03:28PM
When a voltage regulator goes it can either go out quietly doing no damage or pass, in this case 12v, to all the 5v devices killing them all.

You wont know till you try them.

The ramps provides 12v to the voltage regulator on the mega to generate 5v, you have already said this is dead... so you will get nothing by powering the ramps.

If the voltage regulator isn't shorting, you can now only power the mega via usb power

Edited 1 time(s). Last edit at 06/22/2017 03:30PM by Dust.
Re: Fried Arduino Mega What do I do?
June 22, 2017 04:16PM
Yes, so I can power the mega with a usb and the LCD does turn on.

Could I plug in everything and connect the USB to the mega and try to operate the printer?

What do you think caused the frying of my voltage regulator? Could it been a careless mistake of shorting two wires? I am sure that my endstop were pluged in correctly.
Re: Fried Arduino Mega What do I do?
June 23, 2017 12:57AM
You should remove the damaged voltage regulator, just to be sure it won't pass anything. And yes, the Arduino and the RAMPS will work the way you wrote.
I guess you shorted some wires by accident. Maybe you can find it by inspecting the cables and look for damages or melted isolation. An endstop usually won't burn the regulator unless you shorten the 5V supply voltage. You got mechanical or optical endstops? If optical, you have a chance of shortening 5V to GND when the wires get damaged by a screw or similar, this could frie your voltage regulator.
Edit: When testing, use a USB power supply, NOT your notebook or similar. If the Arduino draws too much power, because of some electronic or electric fail, you may toast your computer mainboard. I assume this will be a bit more expensive than an USB power supply.

Edited 1 time(s). Last edit at 06/23/2017 12:59AM by Inhumierer.
Re: Fried Arduino Mega What do I do?
June 23, 2017 01:40AM
a lot of voltage regulars on megas are fried when switch type endstops are plugged in backwards.

The direct short from +5v to gnd will do this nearly every time.

Most pc usb ports are protected form excessive current draw... but if they do trip you often have to completely power down the device to reset them. (ie remove the battery on laptops) They aren’t so protected from excessive voltages...

I use a usb power monitor... so I can see whats going on.

Edited 1 time(s). Last edit at 06/23/2017 01:41AM by Dust.
Re: Fried Arduino Mega What do I do?
June 24, 2017 01:06AM
Usually the power reg should protect itself from dying by short circuit, and when conncting a mechanical endstop, you (or me, at least) take 2 wires - GND and uC input, so a damaged or misplugged cable won't harm. But the devil is a squirrel, you know... ;-)
Re: Fried Arduino Mega What do I do?
June 24, 2017 07:31AM
If you mis-plug it into GND and POS it most certainly will harm.....

I think you will find when a regulator is being heated to destruction it won't care if it fails open or short circuit..usually material is removed from the semi-conductor junction but just occasionally it is bridged by molten debris. When that happens you will cook everything 'downstream'. 'Usually' isn't fail-safe!
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