Hello there,
Let me just say that I am terribly sorry if I made some obvious oversights, but I've been looking around for a couple days now and I cannot seem to find an answer to my problems on my own. So, yeah, forgive the callowness.
I've been playing with a 3d printer, using an Arduino mega 2560, with a RAMPS 1.4 and DRV8825 motor drivers; of course, I made some dire mistakes: I have inverted the polarity on the RAMPS 12V intake and I have placed the drivers in turned around. I turned on the current, tried to use REPetier, failed, and then realized just how screwed I was.
So, I would really like to know if I can salvage something from this pretty paperweight before ordering new stuff. Is there some way to perform a diagnostic on these boards to check if they are fried or not?
Just to be clear, something along these lines: http://forum.arduino.cc/index.php?topic=252323.0
would be fine, just a bit simpler, a bit more detailed on the steps to take, a bit more specific for the 2560 and RAMPS thingamajig.
I would start by removing the RAMPS board and checking that the Arduino Mega can upload and run a simple program like Blink. If that works you could then write a little sketch to pulse the five stepper drivers. Plug in one stepper board at a time with a stepper motor attached to see if the stepper driver works. If a working stepper driver works in all five positions then you are most likely in luck.
If you have a breadboard you could try the stepper drivers separately from the RAMPS board. Just be carefull to follow the Pololu wiring arrangements exactly.
johnwasser:
I would start by removing the RAMPS board and checking that the Arduino Mega can upload and run a simple program like Blink.
Done. It works, apparently; just to be sure, if Blink or Fade work, the board should be ok, right? It's not likely that either could work if there were something wrong with it.
johnwasser:
If that works you could then write a little sketch to pulse the five stepper drivers. Plug in one stepper board at a time with a stepper motor attached to see if the stepper driver works. If a working stepper driver works in all five positions then you are most likely in luck.
Right. RAMPS should just be a handy way to connect the drivers to the Arduino, right? There shouldn't be any... processing I guess?
So I should be able to connect a driver to the 2560 using a breadboard, and then connect the 12 V to the driver and the motor, as Robin2 suggested.
Just a thought: can I have damaged the RAMPS board in any way? can I perform any test on it or should I just check the other components and deduce culprit?
crenzi:
just to be sure, if Blink or Fade work, the board should be ok, right? It's not likely that either could work if there were something wrong with it.
It is most likely OK but it is possible that one or more of the I/O pins was damaged by excess current or reverse polarity. If you want to test them write a blink code for each pin and connect an LED with a suitable resistor to each one in turn.
Right. RAMPS should just be a handy way to connect the drivers to the Arduino, right? There shouldn't be any... processing I guess?
So I should be able to connect a driver to the 2560 using a breadboard, and then connect the 12 V to the driver and the motor, as Robin2 suggested.
Just a thought: can I have damaged the RAMPS board in any way? can I perform any test on it or should I just check the other components and deduce culprit?
The breadboard is an option if you think there is a problem with the RAMPS board. When you are sure one of the driver boards works you can use it to check the RAMPS board by trying it in different positions as @johnwasser suggested. If there is no electronics on the RAMPS board it is probably OK.
I didnt connect the power backwards, but either I had a defective Mega2560 clone, or some stray bit of wire somehow shorted something out, and the Mega2560 literally went up in smoke (almost caught on fire !)
Every stepper driver was destroyed, but the power FET's and other components survived
Actually, it initially looked like one 2 or the stepper drivers was OK, but I found they'd only run one one rotation direction.
I ended up buying 2 more Mega2560's and another RAMPS and also a spare set of 5 stepper driver modules.
So I have one set of 2560 +RAMPS in the printer, and a spare 2560 + original RAMPS with new stepper drivers (as a complete set of spare electronics for the printer).
I'd recommend you cut your losses and buy another 2560 and another ramps (ebay has plenty of people selling 2560+ ramps kits with or without stepper drivers) You may even find its cheaper to but without stepper drivers and get them separately, or buy the Ramps separate from the 2560. People seem to charge more for bundling sometimes.
If you don't do this you could quite easily destroy more stepper drivers, or FET's or the 2560 while trying to work out what went wrong, and in the longer term if you do have time to test things thoroughly you could end up with a spare 2560 etc