Configure the stepper drivers - no readings from multimeter

[mrsamdk]

Im trying to configure the stepper drivers (carve king) and never used a multimeter before.
It seems im not getting any proper readings from my multimeter.
Can anyone see if settings are wrong on my multimeter or if im doing anything wrong in the following video?



I tried following the video here:
www.youtube.com/watch?v=YJSmrbeZUp4

What I did:
- Connected black lead into negative screw terminal and then red lead on trim pot for each of the drivers
- Have female socket connected to the CNC shield (did this before pluggin USB in)
- Have USB cabel plugged into the UNO board (but not the computer)
- Tried turning the trim pot a little on a couple of the drivers (not on the video), but no change on readings

Fan is running and I can see green light on the UNO board.

ps. don't have any alligator clip ... yet...

[Derek the Admin]

The USB cable must also be plugged into the computer so that the blue board can activate the stepper drivers.

Also, for the power, do you have the red wire on the + terminal ad the black wire on the - terminal? It looks to me like only the red wire is there.

[mrsamdk]

I just tried with the USB cable plugged into the computer - still no luck on the readings - same as on the video.

And yup, I have two black (power+fan) in the - terminal (the left one) and two red in the + terminal. I can try and "re-sit" the black ones and see if something could be loose. The fan is running though, but perhaos it can do that with only the red one plugged in correctly?

EDIT: The FAN ofcourse has it's own wires, so ignore my comment about the fan - you naturally refered to the black power wire.

[mrsamdk]

ups wrong topic, ignore/delete this comment

[kec-10238]

I think this is how it goes. shut everything off for 30 seconds. plug in power supply. check for 24 volts. plug in usb cable (drivers should install-if not already). start checking each pot using the black multimeter lead to the black power supply connector and the red lead to the pot screws - the screws don't need to turn much to change. hope that helps

[aforww]

Make sure your multi meter is set to be reading the right thing. Should be set to DC voltage. I'm not sure yours is.

[Derek the Admin]

From what I could tell of the video it looks like you do have the multimeter set to 20 volts DC. I think you need to make one more click counterclockwise on it to get to 2 volts DC.

It sounds like from the other topic your usb port on your mac is not powering the blue Uno board. If it won't power it then the stepper drivers won't be activated. I am a little concerned about a short here. Please unplug all power including USB cables and leave unplugged for 60 seconds. Remove the red board from the blue board. Try to power just the uno board with the USB cable and see if you get that power error again. Also, before you remove it I'd make sure all the pins are lines up and seated. They should only go one way, but I have seen where people have plugged them in wrong or had pins bent away and not seating, causing issues.

[mrsamdk]

Thanks for the input guys


kec-10238 >
After i've plugged in the power supply - where do I place my leads to check for the 24v you mention?


Derek the Admin >
Guess it wasn't so clear on the video, but the multimeter was indeed on 2 volts DC. I think it's setup right(?)



Test 1> So I tested a bit more
- and did what you suggested Derek > removed the uno board and only had that plugged into my computer


Result > No message about USB not being powered

Been very gentle and observant about the pins being bent and re-checked them - they all look perfect.

Test 2> I unplugged all and attached red + blue board together again:
Connected Power > and plugged USB into computer

Result > No error message and UNO board seems to be powered.

_

I then tried to put the leads onto the CNC shield again and the second I hit the trim pot with the red lead, the USB error message appears on my MAC and the green light on the UNO board turns off. I tried the exact same thing on my PC working station and noticed the same behaviour.

So for some weird reason seems USB turns off when I try to measure the trim pot. Seeing USB turns off, I guess the drivers never get the power needed which results in me not being able to get any readings?

[Derek the Admin]

I have no idea why it's doing that as I've not ever run into this. I could send you new boards to try to skirt the issue altogether in case something is at fault there. Do you still need antibacklash nuts?

[oliverc]

if I can give advice, after carrefully watching the video, it seems that you push the probe to strong on the trim pot.
Take care as this is a pretty fragile part.
You just have to touch it gently to get a correct reading, no need to push hard.
To check the 24V just place the probe on the two screws of the blue terminal where the black and red wires are connected.

[aforww]

Sounds like it's shorting when you push the probe and some protection is shutting things down to prevent damage.

Those trim pots are indeed very fragile and sensitive. Be extremely careful with them. Just takes a light touch.

[Bruce]

Make sure the batteries are good in the multimeter. I wasn't getting a good reading until I replaced the 9v battery.

[oliverc]

Oct 17, 2017 13:03:49 GMT Bruce said:

Make sure the batteries are good in the multimeter. I wasn't getting a good reading until I replaced the 9v battery.

Multimeter battery does not seem to be the issue, there is an indicator on the LCD showing battery low, we don't see it on the capture as in yellow on the following picture.



But indeed, it's a point that he can check anyway.

[mrsamdk]

Hey guys - thanks for all the responses.

Soooo a response and update:

Derek the Admin >
Let me get back on your generous offer - I am managing to move forward, through a lot of trial and error aswell as doing a few alternative (non-recommendable) things. But just want to see how it goes and whether it has some consequences (= something doesn't work as intended)

Everyone else >
Battery all new and good. I actually managed to get the drivers configured (hurruaaay!), however seems that the CNC gods are generally against me.

As I see it I was having a mix of issues, i'm still not 100% sure why, but for now I managed to move forward on this part by:

Buying a USB hub. Initially it seems my MAC AND PC disabled the USB port with the message "Unplug the device using too much power to re-enable USB devices". I was getting this every time I hit the trim pot with the multimeter and the UNO Board would turn off and not deliver power to the drivers. At first with the USB Hub I was getting the exact same behaviour. I then changed the delivered cable with the one from my printer (guess it's a common cable used for many things) - now I was able to get readings.
HOWEVER, even using the USB hub, I would still (what seems) randomly get shut down with "Unplug the device using too much power to re-enable USB devices". Each time I had to shut down my computer and boot it up, to reset USB ports.

I then found out driver at top right position, would always show "1" in readings - I changed that with the extra one and was able to configure readings on it now.

ps. local store at my place didn't have alligator clips, so managed to create my own with a clothes pin by following this video: www.youtube.com/watch?v=znl84WjZK4Y

I've not seen the USB message since then, even after having plugged in motors etc. Though the following time will tell whether there's still issues

[Derek the Admin]

Thanks for the detailed update and for documenting the outcomes. It sounds like all is progressing well. Let us know if we can be of any further assistance.