Geeetech

Hello!

I have used my 3D printer for half a year without problem. Today I wanted to change the nozzle, and after doing so, the printer simply shut off and doesn't want to start again (I don't think it hit anything with my tools). First I thought that something was wrong with the Hotend, but even after disconnecting it from the board I still can't get it to start.
Next thing I tried was checking the power supply, but the green LED is shining and I measured the output voltage and it is 12V.
The green LED on the GT2560 is also powered on, but the fans aren't spinning nor is the LCD display on.

The weird thing is that when I connect the printer per USB to my computer, it gets enough power to start up the electronics and I can see the sensor outputs and everything seems normal. That means that the board should be O.K., right?

So does that means the power supply is broken or what? Can I measure at other places to find out if anything else is broken?

Thanks in advance for your replies!

It intends to cause power short-circuit after you change the nozzle,you could test the voltage by voltmeter without the nozzle you change，if it works，than you can confirm the nozzle is bad.

Thank you for your answer!
I have already tried turning on the printer without the hotend, it still doesn't power up. (I tried turning it on with only a single fan connected to test it, didn't work)

Others have suggested that the voltage regulator that regulates 12V down to 5V on the GT2560 is broken, since it still powers up via USB. So now I want to replace it, but my question is, which part is the voltage regulator? On this picture: http://imgur.com/a/nB2Ho it should be the part that reads 7812BG RB512 right below to the big blue coil, is it? But I am not quite sure, my electronic skills aren't that great...

Can somebody post a link or a part number to the right part that regulates the voltage?

Ok, it wasn't the Voltage Regulator, it was the 10A fuse. It blew but it wasn't visible. I measured, and it doesn't work (high resistance). Off to buy a new one!

I have marked the testing point with red circle in the picture.