Help please. Dip switches and mach 3 settings

[john swift]

there must be a detail we don't have to explain why you measure 26V on input P13

which terminal did you connect the volt meters negative probe ?



the printer port ground is connected to the mains supply earth / ground

on the other side of the BOB's opto-isolated circuit

the 5 inputs can not be more than +10V more than
the 12-24V supply ground , input ground & analogue output ground
(which are all connected together on the BOB)

depending on the 12V power supply your using the 3 grounds may be at a different potential to the mains supply ground

small switch mode power supplies such as the ones used with laptops and other IT equipment don't have the negative output terminal connected to earth like PC AT or ATX supplies
they have a small capacitor bridging the mains input & DC output !!!!
( the capacitor is a backwards step just to comply with EMI requirements)

the leakage from a couple of devices is OK but several power supplies can add up to give you a shock

John

PS

[Radu_Andrei]

What I mean that all seems ok, is in comparison with the last state of the machine when the motors were going nuts and the limits were switching erratically.
The bob is not grounded by any individual cable. I assumed that via the usb cable, a ground is provided, which goes to the pc case, and then to the mains.
I did not measure the ground from the mains, but when I touch it, it gives a tingling sensation, like is has some voltage going through it. This is the mains earth as it comes into the property.

The bright side is that it.s all better than before, so I.m still happy, even if, righfully so, Clive disagrees with my so called ˇˇall okˇˇ opinion. I.ll rephrase that. All better than before.

[Clive S]

The bright side is that it.s all better than before, so I.m still happy, even if, righfully so, Clive disagrees with my so called ˇˇall okˇˇ opinion. I.ll rephrase that. All better than before.

Perhaps we have a difference in language. By "working OK" I meant that are the inputs now working as intended , ie if you connect one of the inputs to ground does this show that it is triggered in Mach3 ?

For the avoidance of doubt when we ask for a voltage measurement between an input and ground we mean between the input pin and -ve of the power supply (not earth star point).

Do you get the tingle sensation when you touch the star ground point.

[Radu_Andrei]

Hi Clive,
Yes, all 5 input pins are triggered in mach 3.
The measurement regarding 26v (right now is 24v) was taken between p13 and the gnd situated right next to p15.
Last week, when I connected the control box to the mains, I.ve cut power via the workshop fuse, and wired everything up, but the earth wire does not go through any breaker, switch, fuse etc, it.s go directly into the mains street pole.
On that particular time, it was raining outside, and when I touched the earth wire, it felt quite unpleasant. Touching it now for example, I do no feel anything. I.m taking about the yellow/green continuation as a single wire of the star ground point.

[Radu_Andrei]

P.S. measuring between -12v on the other side of the bob, and the p10 to 15, I get the same readings, measuring the +12 v and p10 to 15 I get 12v into all pins except p13 which has 16v.
Is this the -ve fro the power supply? the - pin of the dc12v?

[cropwell]

It seems that you may have a poor earthing of the mains supply. If you get any voltages on the earth from the pole, you may have a bad /corroded connection somewhere outside.

[Radu_Andrei]

I cannot fix anything out there. I can only disconnect the earth mains wire, and instead add an diy one, like drive an iron rod into the ground somewhere outside. Is this good enough?

[cropwell]

I cannot fix anything out there. I can only disconnect the earth mains wire, and instead add an diy one, like drive an iron rod into the ground somewhere outside. Is this good enough?

An iron rod will corrode quickly, earthing rods are brass or copper.
I don't know how things work in Romania, but in UK Electricity supply safety is taken seriously. I would ask a qualified electrician before doing anything.

[Radu_Andrei]

Back here the hardware part of electricity supply is from the time of communism, E-on just bought the old national company, but did not upgrade anything, at least not in the village areas. Well, they.re still changing the main fuse/clock boxes at some houses today, as there still are properties with ceramic fuses.

So if you.re nostalgic and what to see how was life in the Uk 50 years ago, come over. Maybe even longer than that.
We have some spanish family friends which visit us now and then and they always point out activities going on here, which were present in their country in the 70.s.
The whole eastern block is like this, but slowly we.re catching up. Looking forward another half century, you.ll be able to drive a car here, while being sick of the spaceships you.ll have in uk.

Now back to the problem, if the issue is inside my property, I assume an electrician could change some cables and so on, but they.ll not change the whole electrical infrastructure for me. :)
I doubt that the problem in on my side, as the whole residential wiring was done 3 years ago brand new.
I.ll ask anyway to see, maybe he has some kind of solution.

I.ll post a video very soon with some axis movements to see what you think.

[Clive S]

On that particular time, it was raining outside, and when I touched the earth wire, it felt quite unpleasant. Touching it now for example, I do no feel anything. I.m taking about the yellow/green continuation as a single wire of the star ground point.

I can't see a problem if you could drive an earth rod (copper) into the ground external to the property and connect that to the earth coming into the building.
https://www.tlc-direct.co.uk/Product...xoCHl0QAvD_BwE.

Glad to hear you have finally got it working.