[UT-Matt]

I've just started with a cheap chinese mill, using the woodpecker GRBL v0.9 controller. I've been finding my way around, designing and milling a few pieces, and starting to feel like I knew what I was doing. Then everything stopped.

I tried machining a piece of aluminium and wasn't having much luck - there was a lot of vibration, so much so that the controller would lose its connection to my PC. So I gave up on that and went back to another wooden piece. That was working away until the leadscrew for my Z axis fell out of the stepper motor (grub screw had vibrated loose), and the spindle fell down into the work piece and dug its way in. I think I hit "Reset" in the GrblControl GUI and stopped the spindle.

Now I can no longer move any axis. The spindle can still be started and stopped, but any attempt to move an axis shows movement happening in the GUI, but there's absolutely nothing happening with any of the stepper motors. I have two ideas:

- some part of the electronics either has a dry joint or has burnt out. I'll have to spend some time, understanding how the controller works, before I can use a multimeter to test if the controller is trying to turn the axes or not.

- something in software is blocking all commands from reaching the hardware. I've tried doing a bunch of resets, but I still have this feeling that maybe I've hit some safe mode that has disabled the axes. But I haven't been able to find out where that might be.

Anyone got any ideas?

[UT-Matt]

OK, I've got this fixed.

It was an issue with the electronics. The choke (square grey component marked 470 in the bottom right of the board) had broken internally and the terminal was no longer attached to the coil inside it. I replaced it with a similar one, and my mill now works again.

It seems that only the 3 stepper motors need the 12v produced by that power supply module - the spindle runs on the 24v from the power supply, and the controller power either comes from another power supply or from the USB cable. That's why the rest of the mill was working.

You might also have noticed that I put heatsinks on what I thought were the power transistors that needed cooling. And I wondered why they'd provided 3 heatsinks! I've since learned that the chips on the stepper motor drivers (the small red daughter boards) are the ones that need the heatsinks.

[Weldtutor]

Does the choke (square grey component marked 470) solder to the PCB or push into a socket?
Thanks WT

[john-100]

it is a 47uH SMT choke like this

Attachment 402886


you can reflow the solder on the top of the PCB to remove the choke

Attachment 402884

John

[Weldtutor]

Thanks John-100. As usual a picture is worth a thousand words!
Is there a simple test to check the choke without removing it?
WT

[john-100]

it depends on what test equipment you have


the resistance of the choke is going to be low - probably less than an ohm

what is harder to test for is shorted turns

the simplest way is to send a pulse of current through the coil and watch to see how many times it "rings "

see here :-
https://anatekinstruments.com/produc...bly-artest_kit

from the kits manual
Attachment 402902

to the left of the choke is a switch mode regulator IC (hidden by the heatsink) - probably a LT1074 or LT1076

LT1074 / LT1076 PDF data sheet

Attachment 402904


John

[hangar63]

dear All

I got cheap cheap Chinese 3018 and testing it carefully. it was tested with Laser and then I tested with spindle, Suddenly all 3 axis stopped working. I reset all programs and then it worked and now, when I move the spindle manually it moving with a jerk on 10 and above. 5 is ok. All stepper motors( 3 axis ) has this jerling style along the axis. I read previous post that it has the problem with 470 SMD choke.
I have average skill on electronics and should I change this 470 choke or should re-solder it?
Please advice!!!!!!!

thanks in advance