Converting a THCAD-300 to a THCAD-10?

My first plasma cutter was a pilot arc, cheap chinese unit with no divided voltage output. Since now I am using a Hypertherm Powermax 45xp, I would like to convert my THCAD-300 to a THCAD-10 to get better use out of it, if possible.

Can this be done? Is it just as simple as replacing some resistors on the input side of the card?
I have an oscilloscope and I can recalibrate the card afterwards.

Reading the docs, it seems like the current to voltage chip is the only difference between the -5 and -10. Both resistor networks are 100kOhm.

The input circuitry of the THCAD-5 consists of a current to voltage
converter with a 50 uA full scale range. The input circuitry of the THCAD-10 consists of a
current to voltage converter with a 100 uA full scale range. The THCAD-5 and THCAD-10
have 100K of total input resistance in their input divider section giving them a full scale
input ranges of 100K*50uA = 5V for the THCAD5 and 100K*100uA = 10V for the THCAD10.

The 10 through-hole resistors on the THCAD-10 and THCAD-5
are 10K .1% . The 10 through hole resistors on a THCAD-300
are 300K 1% HVR (3500v rated)

The THCAD-5 input current to voltage converter feedback resistor is 49.9k
0.1% The THCAD-10 and THCAD-300 feedback resistor is 24.9K 0.1%

Excellent, thanks for this information!

Just following up, I switched out the 300k resistors for 10k resistors and recalibrated the board. Seems to be promising with the frequency values I measured.

0v 118.2kHz
10V 920.8kHz

Took a measurement at 7.0V and it was spot on as well.

Not the prettiest soldering job...

Thanks PCW!

why all the kapton tape ?

I previously had this mounted inside the plasma cutter and didn't want it shorting against anything