Issue with Ohmic

[Retro]

Hi there,
i purchased my Ohmic Probe and installed it. I cut a few pieces out of 3 mm Steel and it went great. Then i switched to 4 mm and a much more complex file.
After 10 pierces or so it stopped working properly. First it worked often then not at all. The torch came down to the workpiece and it sensed the material. Alright. Then a few pierces later it came down and the ohmic already sensed the material way before it touched it. At first i thought there was a spatter between nozzle an shield. One time it was like this and now i work with new consumables and nothing changes. It still doesn't work.
When i shut down the Hypertherm PM 85 it opens the circuit. It seems like theres somewhere a shortcircuit.
What can i do to test out where to fix this problem? I have no clue why it worked at first and now not anymore. I tried to unplug the cables for the torch firing - nothing changed. I hope the THC isn't the problem this time - it works like a charm again!

[tcaudle]

I would help to know the brand of the Ohmic probe. Those devices have to handle a lot of abuse . Typically they have noting to do with the torch firing or the THC in terms of it working or nor not.

[Retro]

i used this one here:
https://www.ebay.de/itm/266290356369

[acourtjester]

In the past I have use a Kemo water switch many others have used it too. It is real simple to hook up the sensor input is wire to the table frame and the other wire to the torch tip. The relay output goes to the BOB input trigger for the probe. You should be able to find on in Europe easy.
https://www.kemo-electronic.de/en/House ... 2-V-DC.php
I also have used this module with great success I buy them from eBay, they come in 3 voltage power input, I use the low input for the trigger signal.
DC5V/9V/12V/24V 1Channel Optocoupler Relay Module Support High Low Trigger
this is a US eBay supplier you may see about eBay over there
https://www.ebay.com/itm/335152878919?_ ... 7494CCDPZV

[tcaudle]

Basically its a continuity tester . So the probe on the torch head contacts the table (material 0 and is senses the short )
A ot depends on the power sure that drives it and how that relates to the plasm power source.

To test all you should have to do is string a wire from the table/meatball to the probe you have on torch and watch the inputs on diagnsotics to see if it come son. The only indicator I see is the power so that may only tell you if its getting power to run.

Under certain conditions the shield of the torch can get pals am voltage on it and it needs to not come in contact with a ground referenced suply voltage .

Ohmic sensor are basically a continuity tester and can be used to test themselves. If yours quit working and its getting voltage to run the circuit then its time to return it for replacement

[Retro]

Theres a blue LED that comes on when theres contact.
I wired it directly to the BOB like the instructions said. Maybe theres smth coming the wrong way?

[tcaudle]

Theres a blue LED that comes on when theres contact.
I wired it directly to the BOB like the instructions said. Maybe theres smth coming the wrong way?

If it was wired wrong it would never have worked .

he blue LED may not be ont he acutal output of the module but in the circuit and it there is isolation to the actual output THAT part might be bad. You have to determine if the INPUT itself is working to eliminate that part. Then its down to the module

If the unit is sending a signal that should be easy to determine. Inputs can typically be checked by simply shorting them to the input common and seeing if the input goes active in the diagnostics screen (provided your control software has that feature)

T

[Retro]

Alright - my shop must be bewitched or smth! I works again just like a charm... I don't get why. First i stripped off the "measuring wires" and changed the sensivity. All the way up it became a circuit. Then i screwed off the wires from the power supply and mounted them again (except for the Probe to the BOB). Same thing, everything seems alright. Then i took a wire and shortet the "measuring ports". All the way down nothing happened, all the way up continuity. Alright. Then i went for the middle and it worked again. After that i wired the same wires again to the torch and it seems to work now. Took a look at the consumables and the shield was dirty, cleaned it - works. Changed for FineCut to cut some stainless - works. Strange...

The only thing now that bothers me seems to be the quality of the steppers. When i let it drive the steppers seem to block or smth like that. Maybe its the driver... But all of them are doing the same.