Rtech P50HF with THCAD-300

I have the P50HF plasma cutter from Rtech, which is working very well with my DIY table and PlasmaC.  I currently have no THC and wish to use a mesa THCAD to do this.  I know that I cannot connect the THCAD-300 across the output because of the HF / HV start, so I need to work out where inside the machine I might be able to do this.  Attached are the supplied schematic and some photos of the inside of the machine if anyone is able to help - I am sure this might be of use to others as well.  Many thanks in advance.

The circle with V in it, that is where the THCAD should be wired.

Many thanks for the quick reply - I should have seen that!!

Just to clarify, I can identify T2 and T3 easily, but not R8, C10 and C11, can I take the connection anywhere between T2 and T3, and then measure to the output line or is it critical exactly where? Thanks again

Yes.

I have connected a multimeter between the ground clamp output and the point between T2 and T3 as above (on the right hand end of the yellow coil in photo 4 above, where the nut has been painted with red).

I used a cheap multimeter just in case!

Measuring high range DC (600v) , there is a flash from within the meter as the pilot fires, which I guess implies there is still HV present at this point. I am reluctant to install my THCAD-300 until I am certain I will not fry it.

Are you able to offer any further advice?

Many thanks

Did the multimeter survive ?
Try this.

It's been a while until I had time to try this - but it works perfectly, Many thanks

Nice, thank you for reporting back.