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are my stepper drivers dead?

Posted by RickRap 
are my stepper drivers dead?
May 10, 2015 10:17PM

Started a 5 hr print run before going to bed. Next morning discovered the filament had tangled in the reel. The extruder kept pulling and pulled the reel down from it's perch. The reel fell on top of the controller board. The print had stopped at some point. Not sure if it was due to the reel falling on the board or if something else happened. Now none of my steppers are working. I had tuned my drivers earlier to about 1.3v based on some recommendations I found elsewhere.

I measured the voltage across the pots and the max is around .65v. Adjusting the pots in either direction makes the voltage go down. Could the stepper drivers somehow have gotten fried?

This is a printrboard clone used in the QUBD TwoUp.
Re: are my stepper drivers dead?
May 10, 2015 10:53PM
Are you sure they are getting the "En" (enable) signal? If the controller is not starting then the drivers wont do anything.

Can you connect to the board?

Can you turn on anything else? Fans running, heaters etc?

Can you see the board in windows device manager?
Re: are my stepper drivers dead?
May 11, 2015 12:23AM
yes. Fans, hot end and bed are working.

I can connect to the board and I'm able to see it in repetier.
Re: are my stepper drivers dead?
May 11, 2015 02:05AM
Depends on where it got hit... a PCB can get cracked wherever and it breaks the connections within the layers of the board. I think if you start checking continuity while the power is off you'll start seeing broken connections... most stepper drivers are lined up so if he really got hit I expect that you'll see broken connections along the line of where the filament reel struck it.
Re: are my stepper drivers dead?
May 11, 2015 05:31AM
The trimpots on the stepper drivers are also really fragile and can break easily on impact. So check for cracks in the white ceramic base of the trimpots.
Re: are my stepper drivers dead?
May 11, 2015 07:48AM
I am just thinking that it is strange all of them died. That indicated a problem downstream from the stepper chips. Now that we know the Atmel chip is still OK then somewhere between the two. It is difficult to troubleshoot that.
Re: are my stepper drivers dead?
May 11, 2015 11:39AM
I'm with you. There's definitely something weird. The only thing I can think is that the printer tried it's best to keep going, but with the filament now completely jammed, the extruder, z-axis, and x-axis were fighting hard to keep going. With the voltages pretty much set at maximum, those steppers just kept going even though they couldn't and it fried all the stepper drivers. I don't see any visible signs of the magic smoke leaving the chips, but I'm just going to assume they're fried. I can see voltage across the pots of .65 v max. That's not enough to get the steppers going. I don't know if that's just some kind of base voltage or what, but I'm assuming it just can't get it up.

I have a new board that should be here today or tomorrow. I ordered it a while back because I blew the fan driver.

Plus, I have a smoothieboard waiting in the wings, but I'm not going to hook that up until I get past my learning curve.

I also have a RAMPS + Arduino coming to experiment with.
Re: are my stepper drivers dead?
May 11, 2015 09:38PM
Yeah, you could spend hours testing but I would say your time is better spent just waiting for the other board and test that. If that works you can go back to the other and test one more time.

But the chance that you can fix burnt out drivers or broken copper traces are both pretty slim.

Remember that stepper motors are not like dc motors. Because they apply torque all the time they also run powered all the time. A stepper is a constant output power transducer ( Google that to know more).

Also your drivers should have thermal shutdown and it should be pretty hard to kill them on overheating.

also thermal equilibrium comes pretty quick when mass is so small so if things was not acting up (overheating) after the first 30min then it should not do so 3 h later. I don't see the accident disturbing to such a degree.

I think some common copper trace or, and this is not meant in a bad way because I myself do this all the time - but exist the posibility something really simple is wrong on software side and you are mistaking that to be hardware related because of your accident. You will know if this is the case when you connect the new board.
Re: are my stepper drivers dead?
May 12, 2015 11:50AM
Got the new board in. Hooked everything up. Tuned the steppers and got everything working - sort of.

I flashed the board with same Marlin firmware that I had used on the previous board. The fan came on immediately and won't turn off until the Z-axis moves. Then it turns off and comes back on after about 3 minutes. Plus, the steppers seem to 'lock up' once things get going. I cranked the voltage down from 1.45 to about 1.2 and that seemed to fix it.

But I digress...

I'll start other topics for those. We can consider this topic closed.
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