Arc OK intermitent issues on torch fire

tommylight wrote:

luftlupus wrote:

Attachment not found

The above has the red wire directly connected to Vfield, that is wrong as the arc transfer relay will connect that to ground causing a short to the power supply.

luftlupus wrote:

Attachment not found

This is correct, notice the resistors between the input and the Vfield on the red wire.

I do. If those three resistors were replaced with one of the 1uf caps, would that work as well?

txtrone wrote: Quick side question. I powered my THCAD 10 from the same 'common' PSU as the Mesa board. Is there anything wrong with that? or does it need to get power from the Mesa board?

Nothing wrong with that, it will work either way.
And i do agree on not using any resistor or capacitor, try it without it. I never used any of those on several (count more than 20) and never had issues, but i am pretty sure it might be needed sometimes.

snowgoer540 wrote: Assuming you have a 7i96 you should take it from the encoder area of TB2. Looks like TB2 pins 6 (+5v) and pin 9 (gnd). This is for better noise immunity, I believe.

I am using the 7i76e. I connected FO+ and FO- on THCAD10 to TB3 pins 7 and 8. However I connected the 24V to 5V stepdown power to the 24V common PSU (same one the Mesa is on). I can go back and redo that part.

Black stripes over red wire, there can not be a connection as that would short the power supply when ARCOK is on.
It would be very useful if the poster of that picture corrects it to stop confusing users.

tommylight wrote:

Attachment not found

Black stripes over red wire, there can not be a connection as that would short the power supply when ARCOK is on.
It would be very useful if the poster of that picture corrects it to stop confusing users.

...and the 1uf would be connected that way? Or to the red wire only?

txtrone wrote: ...and the 1uf would be connected that way? Or to the red wire only?

I thought we agreed above not to use any cap or resistor ?
The cap is correctly wired, just mind the polarity.

tommylight wrote: And i do agree on not using any resistor or capacitor, try it without it. I never used any of those on several (count more than 20) and never had issues, but i am pretty sure it might be needed sometimes.

To be fair Tommy, from what you've written over the years, many of the machines you have built did not have a builtin AcOK relay so it was a non issue for them. At least you know to look for the issue if it ever bites you!

tommylight wrote:

txtrone wrote: ...and the 1uf would be connected that way? Or to the red wire only?

I thought we agreed above not to use any cap or resistor ?
The cap is correctly wired, just mind the polarity.

Correct, try without first! Don't fix things that are not broken. Stop looking for solutions to problems that do not exist.

Thanks for marking up the OPs drawing... that was throwing me for a loop. I am working on a schematic of what I have so far, in regard to THC, I will post it up as soon as I can.

tommylight wrote: It would be very useful if the poster of that picture corrects it to stop confusing users.

Can moderators delete these types of things? Or is that censorship? :laugh:

tommylight wrote:

txtrone wrote: Quick side question. I powered my THCAD 10 from the same 'common' PSU as the Mesa board. Is there anything wrong with that? or does it need to get power from the Mesa board?

Nothing wrong with that, it will work either way.
And i do agree on not using any resistor or capacitor, try it without it. I never used any of those on several (count more than 20) and never had issues, but i am pretty sure it might be needed sometimes.

Stefan sent me the CAD drawing he has been working on for his schematic. I modified it to show what I have connected (THC only) ... does this look close?