Two stepper drivers burned already!

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nalmeida
Posts: 46
Joined: Fri Aug 07, 2015 1:18 pm
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Two stepper drivers burned already!

Postby nalmeida » Tue Sep 29, 2015 6:19 am

Hi there, I've been very pleased with my LittleRP and have been printing a few objects with great detail. The only problem I found until now is that I already burned two stepper drivers! I use the A4988 ones and everything works great except when connecting/turning on, on two occasions the stepper driver simply burned. Is there a correct way to connect the machine? The motor is always connected and then I usually connect the power and the usb randomly, should I obey an order on these two? Is there something else that might be causing it? I already checked voltage, rechecked the soldering and now I'm just praying that the third A4988 survives!

goopyplastic
Posts: 236
Joined: Sat Mar 29, 2014 6:16 pm
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Re: Two stepper drivers burned already!

Postby goopyplastic » Tue Sep 29, 2015 12:02 pm

Hrmmm, the main issue is just removing either of the motor cables while the shield psu is attached. Shouldn't be an issue which order the usb / psu are attached however usb first is probably better just to avoid motor jittering while the arduino boots up.

Are you adjusting the vref potentiometer on the allegro drivers? They may be set too high by default. The motors are rated at 1.2amp but you can try setting an amperage of 1amp on the drivers. They shouldn't be more than on the high end of warm by the touch. It's possible that they are burning up from too much heat / too high of an amperage. DRV8825's are less likely to cook.

Scatterplot
Posts: 119
Joined: Mon Jan 12, 2015 12:09 pm
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Re: Two stepper drivers burned already!

Postby Scatterplot » Thu Oct 01, 2015 3:41 pm

Be sure to check your connections- if you have a loose one, it could cause the same symptoms as the motor being connected/disconnected under load.

DanOrgan
Posts: 49
Joined: Mon Aug 03, 2015 10:14 am
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Re: Two stepper drivers burned already!

Postby DanOrgan » Mon Feb 22, 2016 10:28 am

Anyone tried DRV8825 drivers?
SD8825 is hard to find, I am looking for an alternative.
But connections for those drivers are slightly different:


The SureStepr SD has VDD connector and Pololu DRV has Fault connector on its place.

radi2k
Posts: 21
Joined: Mon Sep 28, 2015 8:22 am
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Re: Two stepper drivers burned already!

Postby radi2k » Tue Feb 23, 2016 3:43 am

Check that the motor current is properly adjusted!

A good explanation is on this page:
https://www.pololu.com/product/1182

Sub-section "Current limiting".

goopyplastic
Posts: 236
Joined: Sat Mar 29, 2014 6:16 pm
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Re: Two stepper drivers burned already!

Postby goopyplastic » Wed Feb 24, 2016 7:19 pm

I find that setting .5v vref is pretty safe, we have enough torque that we don't need to go to the 1.2 amp setting. The chips tend to run pretty cool at 1amp, even going down to .8amp is fine.

I also noticed that polulu sends drv's set for 3+ amps stock ... which causes problems as you might guess :D


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