external power on Arduino 2560 MEGA

I am trying to get my board to run through the 12V DC port on the board. I cannot get it to turn on. I will run when the USB is plugged in.

Non of the lights light up. I have checked the source and there is 12V DC coming in and the centre pole is positive.

I would like to run it stand alone with out having to connect it to the computer so any help would be great.

I have attach the firmware I am using just in case that helps.

Marlin.zip (433 KB)

Do you have an official Arduino Mega 2560 board ?

It should turn on when power is applied to the DC barrel jack or to Vin. If it doesn't, perhaps the connector doesn't fit, or the power supply is broken or the voltage regulator on the Arduino board is blown. The DC barrel jack input is protected against negative voltages.

Can you try another power supply ?
Do you have a multimeter ?

I checked and the power is 12 volts and I confirmed that it is 12 volts on the terminals on the board. So I know the power is tranfering to the board. Not sure what is happening after that.

This is a brand new board and it was first connected by USB, then I tried direct. I made sure that the positive was correct before it was connected with a multimeter.

Is the Vin also 12V ? If so, the voltage regulator is broken. Can you see something on the board, like a brown/black burned copper trace or a component that got too hot, or bad soldering ?

The path is like this: Power supply to barrel jack -> diode -> Vin -> voltage regulator -> 5V.
When Vin pin is 12V, and the 5V pin has nothing, there is only the voltage regulator in between, that is the broken part. Or the voltage regulator is not properly soldered, for example when you bought a cheap clone.

Could be the reverse polarity diode is installed backwards, or is blown open.

I checked and there is 12 volts at the Vin pin. No voltage at the 5V or 3.3 V pins.

I checked and the diode seems to be installed correctly when I do a Ohm's check. I get 12 Volts at both ends of the diode.

Not sure where to go next.

IMG_20140831_115908[1] (1.77 MB)

Is the 5v output shorted to anything? Measuring 0 Ohm (or very low #) to Gnd?
If not, sure seems like your 5V regulator is shot.

Getting approximatly 1.5 KOhms

Thank you to you guys for your help. Based on what you are telling me I think the regulator is shot. I will get the supplier to send me a new board and run it off the USB for now.

If the AMS1117 is blown (the voltage regulator next to the DC barrel jack), and the rest is okay, you could remove the AMS1117 and still use the board with 5V.

Is there and easy way to test the AMS1117 to see if it is blown?

Measure the 4 pins. One should be 12V, one should be GND, one should be 5V.

I got the 12V and ground but no 5V.

Seem to have found the issue. Thank you.