Arduino destroyed and all stepper drivers destroyed
September 20, 2013 03:28AM
Hi,

I wonder if anyone can think of any reason why my Arduino (Mega 2560) and all stepper motors on a RAMPS 1.4 all have been destroyed.

I was moving an end stop, and had switched all motors to off in Pronterface, but suddenly the 12V (20A) PSU fan came on, indicating power was being taken.
The stepper drivers started to get hot even though the motors were not moving at all.
I turned the 12V PSU off at the mains, and the turned it back on again, and the fan came on again on the PSU and then there was smoke from the Arduino.

I had a spare Arduino, so I plugged it in, but have found that all the stepper drivers have been destroyed. Well 1 of them works only in one direction, all the others don't work at all.

I've had to order a replacement RAMPS 1.4 and all stepper drivers, but I'm concerned in case this happens again, as its expensive to fix :-(


Is it possible for the Arduino to send commands to the stepper drivers which don't cause the motor to move, but causes them to draw large currents and hence be destroyed ??

Thanks.
Re: Arduino destroyed and all stepper drivers destroyed
September 20, 2013 05:24AM
Command? No. they send 3 * 5v signals, enable, step and direction. And enabling it without moving it is normal.

I suspect you plugged the endstop into + and -... creating an instant short.. But that should be 5v...

The symptoms are like you crossed the 12v onto the 5v line, that would kill the mega and the pololus almost instantly.
Re: Arduino destroyed and all stepper drivers destroyed
September 20, 2013 05:56AM
rogerclark Wrote:
-------------------------------------------------------
> Is it possible for the Arduino to send commands to
> the stepper drivers which don't cause the motor to
> move, but causes them to draw large currents and
> hence be destroyed ??

Steppers consume most current when standing still, thats natural and how they work. When they move, it varies, so its actually a bit less. To me symptoms also seem like a short, 12v on 5v line, or perhaps even a reverse polarity, dunno if ramps has rvp or not (reverse polarity protection), but i dont think it does.
Re: Arduino destroyed and all stepper drivers destroyed
September 20, 2013 07:08AM
Thanks noobman

It's not reverse polarity as the power wiring had worked ok before, as I'd been testing motors and end stops.

Would just driving the motors up and down and not pressing the "motor off" button in Pronterface, cause the stepper drivers to overheat?

They stepper drivers didn't have heat sinks or a fan as it didn't come as part of the kit I got from Blomker.com .

I still can't figure out why the arduino board literally went up in smoke and also still seems to attempt to draw so much current from USB that the 5v collapses to 1v

But I guess the fault in the arduino could be caused by an original short on the RAMPS.
Re: Arduino destroyed and all stepper drivers destroyed
September 20, 2013 07:12AM
Thanks Dust

I guess it's possible, that I shorted something, I can't quit remember, I don't think I was plugging anything in, but its hard remember quite what I did that caused the destruction :-(
Re: Arduino destroyed and all stepper drivers destroyed
September 20, 2013 07:42AM
rogerclark Wrote:
-------------------------------------------------------
> I still can't figure out why the arduino board
> literally went up in smoke and also still seems to
> attempt to draw so much current from USB that the
> 5v collapses to 1v

USB cuts off the power when a device consumes too much. Sometimes this device can burn and leave that usb port without power at all. Measure the usb port without anything connected should have 5v. Measure the resistance of the according inputs of the board, and see if its too in a manner that ohms law indicate if it still draws too much. E.g. if input resistance is less than 20 ohms, for 5v would draw more than 250mA.
Re: Arduino destroyed and all stepper drivers destroyed
September 20, 2013 07:56AM
I already measured the resistance on the 5v input of the arduino, its around 5ohms, fortunately the USB port survived
Re: Arduino destroyed and all stepper drivers destroyed
September 20, 2013 10:19PM
NoobMan: RAMPs has 2 diodes to offer reverse polarity protection on the 5A input (the one that goes to the Mega & the stepper drivers).

D2 is reversed across the input (causing a direct short if the supply is reversed) and D1 is forward biased from the 5A input to the VIN on the Arduino.
Re: Arduino destroyed and all stepper drivers destroyed
September 21, 2013 03:39AM
Well ok, there are two 1N4004 which are 1A diodes that try to protect against a 50A psu short, and a ptc 22A trip point, and ptc is that reacts very slowly. Sincerely dunno if that qualifies as rvp. The ptc and D2 topology would work imo if diode would be much higher current and ptc would be fusible (hence react in miliseconds not in 30 minutes), but with these component choices, D2 cant possibly hold its ground long enough for ptc to trigger - again imo.

And still the steppers power is taken well before that so for what steppers are concerned, this doesnt even matter. So again, dunno about rvp on ramps. If i would had one, i wouldnt try testing it smiling smiley
Re: Arduino destroyed and all stepper drivers destroyed
September 21, 2013 05:03PM
Well something, drove enough current into the arduino to burn out a track. Actually, I can't see any visual damage on either board, even through a 10x magnifier, but I've not had time to buzz the arduino to see which tracks are gone
But something burnt out as there was smoke and light!

I guess that a low value fuse eg 100ma in line with D1 (sorry I initially thought this was D2) would have prevented this, presuming that the 12v PSU supplied the current. I will fit one today!


Edit. I've buzzed the Arduino and the VIN 5V and GND appeared to be shorthed together, I removed the SMD 5V regulator (basically it fell apart as I don't have any solder reflow tools, only a regular soldering iron).
With the 5v reg removed, Vin is OK, but 5V is still shorted to ground somewhere :-(

As I can't see any visual damage to the board, I don't think its going to be possible o salvage the Arduino, as I can''t remove and refit the smd components, one by one, to see if its any of them that are causing the short.

With my existing RAMPS board I've not cut the track from D2 to Vin, as it wasn't possible to remove D2 as I can't get any tools in by the side of the headers for the stepper drivers.

But this will do the trick, I always use the PC to power the Arduino at the moment

BTW.I've ordered another RAMPS, so I'll probably scrap this one, as I cant really trust it

Thanks

Roger

Edited 2 time(s). Last edit at 09/21/2013 07:20PM by rogerclark.
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