Hello, I have just completed upgrading my spindle to a VFD water cooled one. But since doing that my touch probe is closing the circuit (led on) when you touch the bit rather than when the bit takes contact with the plate. I have plugged the VFD to isolate and checked all wires leadings to the black box and nothing screams out at me as unusual. It worked perfectly before and apart from adding the 0-10V connector nothing else was disturbed. Any ideas? Thanks,
Short via spindle body > spindle earth > mains earth > accidental short to DC GND somewhere? Process of elimination, unplug PC (some older computers can develop earth to DC leakage via aging components in PSU or even shorts from cables damaged inside PC - nicked by a screw or sharp panel edge); unplug wiring one by one (shorts could come from a limit switch mounted wrong or pins at connectors touching frame) etc
The issue appears to be with the VFD and by being connected to the spindle with a conductive body the earthed loop is permanently closed. Not sure how to resolve this really
That part is fine... Spindle should be EARTHED. But Earth and DC GND should NOT be connected and somewhere in your system it is. See above
Yes indeed I had read above and isolated the issue to the VFD. Once it is removed from the equation the touch plate is fine as it was before. The VFD is wired correctly and works fine, so I’m not sure how to correct the issue there.
Reread above then. The VFD "must" be Earthed. Thats the symptom The SHORT is elsewhere - something else connecting DC GND (used by low voltage side of system) to AC EARTH (MAINS POTENTIAL SIDE OF SYSTEM)
Hmm, from what I can see my scenario is as such:- I’m using one probe, an Openbuilds XYZ touch plate. The plate has LEDs which normally illuminate when connection is made. As per the test you sent, if I touch the magnet to the body of the spindle the led illuminates straight away. With the magnet attached to the spindle and illuminated if I then tap the plate to the bit the LEDs illuminate brighter with every tap. Indicating some sort of potential difference. If I do the same test with the VFD unplugged nothing happens. ie no circuit is made. if I attach the magnet to the frame of the machine the LEDs are fully bright. So I can see the differences but I’m not sure how to fix it. On the DC side the only physical connection between the Controller and the VFD is via the 0-10V port. Unplugging this makes no difference. Power-wise, the VFD mains connector is connected to the mains correctly with nothing touching gnd/ earth wires etc. All other connectors such as limit switches are fine, and once I unplug the VFD from mains all is fine so I don’t think that there is any Short or leakage on anything there as it was before. is there a any diagram for the probe??
Do the tests... Unplug them one at a time. Particularly if you have any limits mounted "upside down" or without rubber spacer. If its not there move on and do more tests. Unplug the monitor's power cable but leave HDMI (gnd to ac short via hdmi connector passing DC GND from controller > USB to PC > motherboard > hdmi > monitor > leak to AC Earth inside monitor's psu completing the short circuit) Unplug the usb cable (gnd to ac short in PC) Leave VFD plugged into wall (and all other wiring plugged in) but unplug the 0-10v (short inside VFD, unlikely but do test) And so forth. One at a time, put back what didn't make a difference. Soon as you break that short the LEDs will go back out
Rite, unplugging the laptop with the controlls software breaks the circuit and enables normal operation. Only obvious issue is that I can't keep it like that just to run my probe. Any idea how to isolate the mains earth from the laptop?
Anything else attached to laptop? Laptop run off batteries ok just issue when its PSU is plugged in? PSU a 2-pin plug? Try reversing it - live/neutral the other way. Or try a new laptop PSU
Nothing else is plugged into laptop. I'm on a Dell Laptop in the UK so PSU has 3 prongs on the DC side therefore unswappable. I will try openbuilds control from my MAC and see if I get the same issue. next.
