Voltage Present

This one has me stumped
When I try to use the touch probe on first touching the probe to the router I get a spark and a fault comes up on the Y access i have checked all connections nothing appears pinched or loose.
There is 17 volts present between the case of the onefinity controller and the actual machine rails this is with the spindle disconnected from the mains power
Everything on the Onefinity works fine has produced a number of items this week and also used the laser a lot no faults no problems no issues the only issue is the sparking touch probe
The electrical system in the work shop is 12 months old and fully tested
Any thoughts?

Not something I have come across and an old voltage. Maybe a short. A vfd can store charge so may be a short in the spindle with charge coming from the vfd? Are you using the spare controller power outputs in anyway? Spooky.

Andy Spindle is disconnected
Nothing extra plugged into the controller apart from a wireless mouse and a powered usb hub

Hey Darren,

are your machine’s feet grounded?

The 17 Volts could be a potential difference that can easily occur if the machine is not grounded.

Machine isnt grounded, machine is sat on a torsion box made from wood and bolted to a wooden bench
Should i attach a ground wire from the machine to a ground point?

Hey Darren,

since I don’t have my machine yet, I can only be of limited help, but I believe that is what I will do. I don’t see any reason why the machine shouldn’t be grounded. In any case, this will get rid of the potential difference.

Have you verified you are plugged into the right spot on the controller? That seems like something is not connected correctly. Additionally do you have a flex hose running to your vacuum?

Hey Darren,

any metal device that is not earthed can accept charge from its environment and be energised unhindered. There are many possible sources of charge, in the worst case it is a live conductor that has become detached and that touches the metal (i.e. weak soldering point in the self-soldered spindle connector) and which exposes the user to serious danger; however, other sources such as electrostatic charging, e.g. from dust extraction, can also be the source of such charges on the metal parts. The electrical bonding and earthing, i.e. the bringing together of all metal parts of a device, prevents such charges from building up and thus prevents electric shocks or sparks.

Hey Darren,

one question: I assume you have a multimeter. If you measure these 17 Volts between the case of the Onefinity Controller and the rails of the machine, and then if you make a an electrical connection between both (wire) for a few seconds and then remove it again, then did the 17 volts collapse and have disappeared, or are they still there afterwards?

I will try the wire test whilst the multimeter is connected when i am back in the workshop later on
Thanks for all your suggestions, i will post up my findings a bit later
Aiph5u, when is your machine due? It will be worth the wait

try disconnecting the “powered” usb hub and see if it is still present.

1 Like

After much unpluging and pluging including swapping cables
The only way to reove the voltage is to remove the Y2 cable from the machine (y right side motor)
The socket in the end of the right rail has 4 connectors in it the top right one has continuity with the rails so i am assuming a fault in the socket the internal cable or the motor?

Any thoughts?

Pretty sure the Y socket should not have continuity with the rail!

1 Like

That was my thought, not sure if Onefinity monitor the forum or weather to drop the a line

Hey Jim, hey @CSM Darren,

yes, I agree,


you did not answer my question:

If, with multimeter connected between the case of the Onefinity Controller and the rails of the machine, and you see the 17 Volts, and then you make a an electrical connection between between the case of the Onefinity Controller and the rails of the machine (a short, with wire) for a few seconds and then remove it again, then do the 17 volts which collapsed and disappeared then (and the question is): Are the 17 Volts then still there again afterwards? Immediately?

Hi sorry
I connected a wire from the machine to a know good earth point when i swicted the machine on a Y motor fault appeared on the screen and i could reset the stop or cancel the fault i then powered down before removing the temp ground wire
I am convinced that the fault is in the right Y rail internal cable or motor or socket which fills me with dread as i assume its a machine strip down job

Yes I agree. There should not be a connection between a motor driving conductor and the rail.

And without this fault, you should be able to ground your machine. In this faulty state grounding it renders the machine unusable.

you may proceed with error diagnosis by disconnecting the stepper, but I’m sure it’s the cable or the connector of the cable.

As I think I already stated earlier, these tin-plated Molex/Amphenol Connectors used on the Onefinity are the first thing I will throw away when I will receive the machine and replace them with decent gold-plated industry standard circular connectors.

These tin-plated Molex connectors have been a disease in computers since decades, can’t say how many data loss they caused, and they’re still there, e.g. as ATX power supply connector. The problems that this causes, of which I can report from many years of experience, are in my opinion not at all appropriate to the requirements for the reliability of computers. It’s just money-saving on the part of the manufacturer.

Tin-plated contacts are tolerable if they are plugged together exactly once. Disconnecting and reconnecting them causes problems. Tin is not very hard and the problem is that the wear and tear that occurs with every mating cycle leads in the long term to the contact coating chafing through, exposing the copper alloy underneath, which is even more susceptible to corrosion. And even without touching, the tin itself oxidates with time (and tin oxide is no more a conductor).

I’ve been following this forum since March, and the problems with the cables and connectors keep coming up from time to time. But at least Onefinity seems to have very good support!

1 Like

I bet one of the lines got pinched inside the steel tube, or the plug hidden in the middle of the tube is the cause. I replaced all those wires with a continuous run of IGUS CF6 shielded cable.


All sorted there was a short between the right Y rail motor cable and the machine body Replacement cable on its way from Onefinity

1 Like