Valid Arc Lost, Thcad 300 config & Plasmac override

I was thinking how I can add some voltage...did like that...
multimeter measuring resistor...could I use maybe a 9V battery??

result jumping voltage!! I guess the measurment is not a steady voltage...couldn't add videos here?
so made screenshots of the video!!




arc ok minimum voltage was set to 50 V...

would you say everything survived? :huh: :whistle: :pinch:

I would wait for PCW to confirm, but something is still happening and the input of 7i76 encoder seems to be working properly.

I don't think you will have damaged the encoder. The THCAD totally isolates the plasma side so it should be fine.

If you still get a blinky yellow light on the THCAD, the isolator survived
which likely means none of the nastyness got to the 7I76e

if I reconstruct the one side with a 2.2nF cap and solder it together should the THCARD be fine as well? the reading came from the card...

question is: from the beginning thcad with settings to F/1 the card showed withe the right settings in plasmac offset and scale it showed -41 Volt.
could it be that freq: on the label is wrong?

Where can I connect the card now? any hint where the point might be without the inducted HF ? just the voltage from the power supply.

thanks to all!!

The -41 volt is coming form the fact that in the absence of a working THCAD, you have a frequency of 0 on the encoder. This normally should be the Offset value at 0 volts. So the software is deducting an equivalent of about 41 volts (the offset) from 0 which results in the negative reading. See linuxcnc.org/docs/devel/html/plasma/plas..._with_the_mesa_thcad

So the thcad card is broken? The reading I got today?

Sorry I am slow thinking... Since I never had a 0 V reading....it might have been dead from beginning then.

Slow thinking... I also didn't get: on probe to which hight the head goes?
Cut or pierce?

You can read the THCAD frequency directly by setting the encoder scale to 1
and reading the encoder velocity pin. This should allow you to check the 0V
offset frequency.

f/1 seems bad news....

f/32


not stable.....

with the calculated values at f/32 (from the label) I get now 0 Volt +- sign changes....great..but the frequency was not shown...

Fred, your screen dump shows the velocity at 3540

And your original post said it should be 3540. So its perfect! Nothing ins broken!