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I am building a mini-cnc laser engraver as shown in this intructable and this youtube video.

I have built the circuit (minus the jst connector and two male pins at the top left of the board) and have attached a stepper motor from a dvd drive. It worked like a charm, but made a loud ringing noise (like tinnitus.) I proceeded to test it with laser GRBL, and it moved great, but gradually started missing steps, at first only in one direction and eventually in both. After a couple hours of being connected, it wouldn't budge at all. I switched the motor for another motor, and tested it again. This time the motor was much shorter-lived. It made 5 steps perfectly and then just shut off. You could hear the motor try to turn, but it was like it didn't have any torque at all. What could be the issue? (I also tried it on the other axis with the other motor driver, no change.)

It's also worth noting that at one point both the positive and negative (ground) cables from my power supply made contact with metal at once, throwing a spark. However, the steps were already beginning to be lost before that happened.

As per your request, I have attached the circuit layout I am attempting (it's identical to the one in the tutorial) as well as a picture of my physical circuit board. (sorry, a link was my only option as the pics were to big for upload) I know the soldering is pretty bad- I have a giant soldering iron. I don't see any shorts though.

Intended Layout

Drake Ford
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    At what voltage did you run those steppers? – Gerben Jun 11 '19 at 13:23
  • @Gerben im going to be completely honest, ive never attempted anything with circuit boards or arduino before. I followed the instructables, which tells me to use a 12v power supply on the screw terminal after everything is hooked up. – Drake Ford just now Edit Delete – Drake Ford Jun 11 '19 at 22:26
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    Your steppers might be 5V instead of 12V. Or his are 5Volt to, but has set the A4988 Motor Drivers to limit the current (with the small potentiometer on the board). – Gerben Jun 12 '19 at 09:37
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    To progress this further I think you'd need to edit your answer to add the part number(s) of your components (preferably along with with their specifications) and along with the schematic / circuit layout you have implemented (rather than the one from the tutorial). – AJP Jun 13 '19 at 08:56
  • @AJP I have done as you suggested – Drake Ford Jun 15 '19 at 02:59
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    You can upload images as part of your question, you know. That is far preferable to sending people off-site to some link that might go down in a year, making the question hard to follow. I also don't see the part numbers that were requested. – Nick Gammon Jun 15 '19 at 05:07
  • Sorry my suggestion of a circuit layout was only partially useful as this is what you hope you've wired up @DrakeFord but it's always good to see the actual wiring up. And as Nick's suggested a picture of your circuit plus a picture of the intended circuit layout would be good. There might be a simple mistake here. And secondly again, what are the motors you are using (their part numbers) and their resistance and amperage. You'll need these to know if they'll work with your A4988 drivers: https://learn.adafruit.com/all-about-stepper-motors/matching-the-driver-to-the-stepper – AJP Jun 15 '19 at 08:54
  • @AJP I had to link my pictures of my circuit- they were too large for upload. I do not have my stepper motor part number, since they were harvested from a DVD drive. My DVD drive model number is LITE-ON SOHW-1633S – Drake Ford Jun 15 '19 at 16:16
  • You can scale the pictures down. There should be some part numbers on it somewhere. Is there *no* writing on it? Not a stuck on paper label. No dot matrix printed numbers. Nothing? If you can't find out exactly what the motors are and are capable of I'd go back to experimenting (though you may fry your driver if the motors draw too much current). Try measuring the voltage and current and see if it's acceptable for your A4988 drivers. If so try reducing the speed of driving the motors. Also try with them disconnected from any physical load... maybe they're just stalling. – AJP Jun 15 '19 at 16:23
  • @AJP the only number i see is E232171 which is printed onto the flexible pcb where the 4 solder joints are on the motor. other than that, nothing. The motors have no physial load. – Drake Ford Jun 15 '19 at 16:28
  • You seen this @DrakeFord? https://www.eevblog.com/forum/projects/dvd-rw-(liteon)-teardown-stuff-details-(motors-laser-diodes-ir-red-visual-etc)/msg706604/?PHPSESSID=o815ofg9mgsifeduvk0akvpsa0#msg706604 – AJP Jun 15 '19 at 16:52
  • @AJP yes I have. I am suspecting that I might have a bad voltage regulator on the board and that it is feeding 12V into the 5V Stepper. Maybe replace the voltage regulator? – Drake Ford Jun 15 '19 at 17:22
  • @DrakeFord if you think the voltage regulator is at fault then isolate that first. If it's producing 12V you'll likely be damaging other components. If you have a DVM (Digital Volt Meter) then measure it's output and see if it's behaving as intended before just replacing it. If you don't have a DVM, then borrow or buy one... it's an essential (and cheap) bit of kit of hobby electronics. When debugging all these problems following this guidance is very powerful: https://stackoverflow.com/help/minimal-reproducible-example As you reduce the size of your problem it becomes easier to solve it. – AJP Jun 15 '19 at 20:31

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So the problem was that somehow the potentiometer had reset its own vref output. I couldn't adjust it after it did this. I replaced both drivers and it works like a charm now.

Drake Ford
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