Help with Mega board.

Greetings, I just assembled my 101, and had started calibrating every thing was working fine up to the point I was testing Vref of the stepper drivers, the board stopped working while I had multimeter on the driver screw head(potentiometer). I'm assuming I must have shorted out the driver.

-When I plug in the USB the board(led) and LCD screen boots for half a second and then turns off.
-When I flip the power switch I have power to the LED strip, and the XYZ stops show power as they are in home position so their red lights are on.
-When I test the circuit I get a reading saying the circuit is open(OL), which would make sense if the board is shorting or fuse is blown, but I don't understand why the LED's are still powering.
-The next logical step I can think of would be to replace the Stepper Driver I was testing with the spare, and or take off the ramps shield and test the mega by its self, to isolate the problem. I am new to all of this so I figured I would see if some one sees a easy possibility I am not aware of or could better direct me on what to troubleshoot.

Any ways any and all help would be appreciated. I am looking forward to my first print.

10kwatts:

It sounds like you have a "failure to communicate" type problem. It may be a corrosion problem on the mating pins of the connectors. The first thing to check is that you are getting 12v to the board itself so as to rule out the power supply. The second thing to try is to separate the boards and ensure that they mate properly together checking for a bent pin or misaligned pin. Then pull off the connectors one by one and toggle the power supply each time. The last thing to try is pull off all the connectors and see if the board's led gives you the blinking led. Start putting the connectors one by one back on the board to see if one of the connectors kills the board and turns off the power.

So there was 12v but wasn't registering at first with USB connected also(i think had to do with communication issue board was having),
went through your suggestions three times, and on the third time finally found problem.

Problem was the RAMP driver as was originally suspected, how ever it wasn't until I had stripped every thing off to just the mega board, and then reloaded the software and hit reset on the mega board as well as resetting the RAMP shield then adding every thing back one piece at a time, that I was able to see the problem from the driver. At which point it was causing whole different set of errors (flashing voltages and minitemp errors).

I'm guessing when I fried the Stepper Driver the first time it caused some type of syntax error which made the board semi dead. How ever after resetting every thing, and then adding every thing one by one back to mega as well as RAMP shield(starting with thermistor so LCD screen would load) I was able to see which driver was the issue.

Thank you very much Normoldboy for reply and suggestions. On to the next learning curve :slight_smile: