A stepper issue

Mostly Printed CNC - MPCNC Troubleshooting
1

I have had both the x and Y axis running nicely when testing.

Today I started my first project and all was going well. Then it got a bit noisy and I in notice Y2 stepper isn’t working, the truck is being dragged by Y1 in both positive and negative directions.

I powered everything off and disconnected the Y2 aviation plug. I tested the stepper again by putting LEDs across the connectors and manually moved the Y axis , the LEDs illuminated so connections were good.

I then swapped Y1 and Y2 over and as expected the Y2 moved and Y1 didn’t. That would appear to rule out a dodgy connection between aviation plugs and the board.

I did get it going again briefly but didn’t last long. I am suspecting dodgy soldering on my part. Is there something I have missed. Are there manual M-Codes I could enter to test also?

Thank’s for your time

2

At least I can assure you it’s probably not the grub screws if swapping made a difference. :smiley: That’s something for a start. :slight_smile:

3

That would eliminate a wiring issue between the aviation plugs and the motors, right? The aviation plugs to the board is still suspect.

I can tell you that motors almost never fail. They are mich simpler than they look. Wiring issues at the connectors are very common (probably because we all hate it, so we tend to ignore that possibility and rush through it).

Explain this led setup? The drivers are capable of pushing 1-2A. Did you use big LEDs?

4

Yep, you’re right. Issue was aviation to board. My soldering was fine but an issue with a dupont connector.

5

I believe that what he means is:

Attach LEDs between A and A’, and between B and B’ on a stepper motor. In this case, probably to the aviation connectors going out towards the motors. Move the motors by hand. When you do, the motor will generate some back EMF, and the LEDs will flash. It’s not 100% sure, but it will at least tell you that you have continuity from the connector to the motor, and that the motor coils aren’t burnt out.

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6

Ah, ok. I thought you were trying to test that the driver was driving. I think that might work if we could find some 2A leds. :slight_smile:

7

You could probably test them that way if you turned the v ref way down so you where only putting out half an amp or somthing right?

8

The regular 3mm LEDs usually max out at about 0.02A, or 20mA. You would need something specifically designed for that much current. There are 50W LEDs out there, but they need their own kind of science to use them.

9

And a whole lotta heat-sink too!

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10

Naw. A 630 ohm resistor in line would do it. The driver won’t like not being able to drive the current, but can’t supply more voltage than the supply, so 12V into a 630 ohm resistor is 19mA. Less if you count the Vf of the diode (most 12V kits are 470 ohm.)

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11

Yes. But that is cheating.

12

I just used a random LED I had in an Arduino project kit. Saw the technique on a random you tube article. I am afraid maths never entered the equation.

I did progress to putting a multimeter across the cables and measuring resistance. Not nearly as satifying

13

You’re fine. Powering the led from the motor is NBD. I thought we were trying the opposite, which got me curious.