RAMPS 1.4 keeps frying stepper drivers

I recently built a Mendel Prusa i2 with RAMPS 1.4.

I wired everything up and flashed the test firmware that simply moves all the stepper motors around.

At first everything seemed to work fine, then after a few minutes the first stepper motor started vibrating, then spazzing, then dying. The current potentiometer was at about 25 %.

This whole thing repeated itself a few times with different drivers and slots and now I have 3 dead stepper drivers and apparently 1 dead stepper motor.

Does anyone have an idea what could cause this or how I can debug it without going through a ton of drivers?

Thanks!

What board type did you set in the firmware? Maybe some pins are assigned the wrong way?

I killed a few drivers by accidently not plugging the stepper cable onto all 4 posts and/or pulled them off, while the power was still on...
-Olaf

The wiring seems to be OK as it worked for a while, but I'll double check later today - that and also the soldering job.

I never unplugged the motors while the board was powered.

The setup worked for a few minutes and I didn't touch anything, which, I think, eliminates some of the more common causes.

Edited 1 time(s). Last edit at 06/03/2015 07:01AM by anonymous.

when moving did it reach and activated the endstops?

No, they weren't even connected.

Quote

The current potentiometer was at about 25 %.

You should set it to a certain voltage, like 0.35V to start with.
I´ve had different drivers and some need to be turned counterclockwise to raise stapper current.
-Olaf

I resolved the problem. The pots on the drivers I am using seem to be very low quality and they aren't linear at all. Turning them in one direction makes the current go up and down randomly. Sometimes turning them all the way in one direction causes almost no current to flow, sometimes the same setting means all the way up.

I got them to work using trial and error while constantly having a finger on the PSU off switch.

Thanks for your input!

Quote
anonymous
I resolved the problem. The pots on the drivers I am using seem to be very low quality and they aren't linear at all. Turning them in one direction makes the current go up and down randomly. Sometimes turning them all the way in one direction causes almost no current to flow, sometimes the same setting means all the way up.

I got them to work using trial and error while constantly having a finger on the PSU off switch.

Thanks for your input!

I'm glad you got to the bottom of it!

Software control of stepper motor current is so much nicer.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].