Oups, I think I broke something...

Hi everybody,

I am trying to build my first 3D printer (Prusa i3).
I was testing my stepper motors with my Mega2560 + RAMPS 1.4 + A4899 stepstics.
To do so, I uploaded a test firmware that basically just rotates the motors endlessly.
My motors did not turn but just made a sound, so I decided to check the voltage on the stepsticks to adjust the current.
Doing so, my hand moved and I accidentally created a short-circuit between two pins on the stepsticks and heard a sharp noise...

Since then, no sound at all from the motors.
I tried with different motors and stepsticks, nothing.
I have still lights blinking on the RAMPS.
I think I burnt some component, but I do not know what.
Any idea guys?

Thanks!

Poliapov

Edited 1 time(s). Last edit at 10/15/2014 02:50AM by Poliapov.

Depending on what pins you shorted, you might have damaged the mega board. Can you communicate with the Arduino, such as programming it as well as send and receive commands? Just the communication LEDs flashing isn't sufficient as they are flashed by the ATMEGA16U2 controller that handles the USB communication, but the ATMEGA2560 controls the printer. If the ATMEGA2560 is cooked, you may appear to be communicating with the board with flashing LEDs, but you're not.

Hi,

Thanks for your reply.

I checked, the two pins I connected were Vdd and Gnd.
I was able to communicate with the mega2560 and to flash it correctly.
I also tested the output voltage of the heatbed and hotend (as the test program was supposed to switch them on and off) and it seemed to work.

But I still did not have signal going to the motor.
I thought that maybe I burned one spot for the stepstick that prevents the others to work correctly (as I have only one extruder, I can use the fifth slot).
So I removed the stepstick and the jumpers.
I put it back and then I really fried the ATMEGA2560, and I mean I really burnt it with heavy smoke and all...

So, my question is now, is my RAMPS dead too? and more importantly, will I burn another Mega board if I plug it to it?

Edit: I do not expect you to magically answer these questions, but just to help me to test the board to know what is wrong.

Thanks for your help,

Poliapov

Edited 2 time(s). Last edit at 10/15/2014 01:50PM by Poliapov.

I just noticed somehting, maybe I did something wrong with the motor wiring in the first place.
My motors (42BYGHW609) have 4 wires with the follwing colors: Red / Yelow / Blue / Green

As I have read everywhere that the pins are supposed to be Red / Blue / Green / Black, I just assumed that Yellow = Black on this model (it was stupid not to check anyway, I agree).

On the datasheet, I read:
Red: A+
Green: A-
Yellow: B+
Blue: B-

But I read there [forums.reprap.org] that there is indeed two different and confusing notations and one should do the following conversion:

1A => A+
1B => A-
2A => B+
2B => B-

Here [reprap.org] I read that the good wiring for the A4899 should be:
2B 2A 1A 1B

So it should be Blue / Yellow / Red / Green, right?

There is no standardization of wire colors with steppers. They often are similar, but there's no guarantee and probably shouldn't be relied upon, especially if you are having issues. You should refer to the spec sheet to see if it indicates what the wiring should be, or you can just use a multimeter. You should be able to measure the resistance between pairs of wires. If any two wires measures open or very high resistance, they are not a pair. You can again refer to the motor spec sheet to see what the expected coil resistance is. It may not be exact, but it should be close. Once you've determined which wires belong to each pair, it can just take a bit of testing to figure out which is the + and which is the -. It may take a few flips of pairs to get it right, but having the polarity reversed shouldn't fry the driver.

Well, this advice makes so much sense right now, but in my defense, most of the diagrams one can see on the internet just show the colored wires.
Thanks again for your help dude, once I have received my new hardware, I will try not to burn it up again (I hope).

Edited 1 time(s). Last edit at 10/17/2014 09:21PM by Poliapov.

When you short a driver chip like that it often blows all the drivers. It is very important therefore, that one driver chip only should be inserted and adjusted for voltage. When the first one is done, remove it and place the second one in and adjust, and so on for the remainder. When they are all done, then install them all.

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Waitaki 3D Printer