Mesa THCAD-10

110 to 130 V when cutting most likely means the output is 1:1
Not being present at Arc start is a bit mysterious

So do you think a resistor is needed? I was thinking i would need to be inputting 100 to 200 volts for the thcad-10 to output the 0-10 volts?

n2fastcars75 wrote:

I was only getting .112 of a volt at my encoder a input pins on the 7i96s board while cutting with the plasma.

n2fastcars75 wrote:

I was thinking i would need to be inputting 100 to 200 volts for the thcad-10 to output the 0-10 volts?

Sorry for being blunt, but stop, go read the manuals for both cards (not everything, just the 3 to 5 pages) then go back at it.
THCAD does not output "voltage" as you expect it, it outputs frequency that is counted as encoder velocity by Mesa 7i96S.
So, first check the wiring from THCAD to Mesa 7i96S, then check the setting in PlasmaC or QtPlasmaC for scale and offset, and if those are correct you get 0V on screen when the plasma is PF and THCAD is powered.
Do not try to cut before making sure all this is working.
You can use a 1.5V battery on the THCAD input side (disconnected from plasma) it should give roughly 45V on screen.

Thank you for pointing me in the right direction. Im using PlasmaC but im thinking i need to go to QtplasmaC. I was getting a -36 reading on the axis gui all the time without any change after firing the torch like .050 from a steel plate for a few seconds. Had a little change when i changed my values in the config tab but always stayed negitive. I looked though the manuals and did notice that the thcad-10 board should have a cr2 yellow and cr5 green led working on the board. Im only getting the one yellow led. Another thing i did see as well is that the 7i96s has jumpers for the encoders on it. Im thinking it needs to be set for single-ended (TTL)? There's a commet about only needing to use a + wire to the encoder? Im using fout+ to encoder+ and fout- to encoder- does this sound right? I also have 65 or so volts coming into the thcad-10 board with the 2.5m ohm resistor on the pin that is connected to the ground lead. Does this sound right? I see others say you need 1m ohm on each pin. I got the 2.5m ohm for a guy doing a build like mine with the same plasma cutter. He had noted that peter from mesa had suggested that size to use. So hadn't done much searching on resistors until now. I know there's more i need to check as well. Going to use the manuals and try my best to quite getting myself more confused reading posts on here! Thanks Again!

n2fastcars75 wrote:

I was getting a -36 reading on the axis gui all the time without any change after firing the torch .....

You should have stopped there and check everything, that should read 0 when THCAD is wired and set up properly regarding scaling and offset.

n2fastcars75 wrote:

I looked though the manuals and did notice that the thcad-10 board should have a cr2 yellow and cr5 green led working on the board. Im only getting the one yellow led.

The green one should blink when THACD is powered.

n2fastcars75 wrote:

Another thing i did see as well is that the 7i96s has jumpers for the encoders on it. Im thinking it needs to be set for single-ended (TTL)? There's a commet about only needing to use a + wire to the encoder? Im using fout+ to encoder+ and fout- to encoder- does this sound right?

Yes it is correct, and no do not move the jumpers.

n2fastcars75 wrote:

I also have 65 or so volts coming into the thcad-10 board with the 2.5m ohm resistor on the pin that is connected to the ground lead. Does this sound right?

That does not seem OK on many levels, even with the torch on you should get under 10V on THACD inputs, so make sure the shop, plasma source, machine, computer, ALL have proper grounding, This is not negotiable on plasma machines, no ground usually means dead parts.

n2fastcars75 wrote:

I see others say you need 1m ohm on each pin.

Does not matter much, i prefer 2, but i mostly use old plasma sources so it makes it safer in case a wire is nicked on the way to THCAD.

Its been a while and made many changes last night and still cant get thc to work. Still have a negative voltage on qtplasmac gui. I got it installed and running thinking it might make things easier. Made all changes adding extra grounds to table. 8 foot grounding rod connected to table with welding lead wire. Isolated my control box from the plasma table as well. Also added relay for torch on function and for arc ok i added a optocoupler so the plasma cutter is isolated as much as i can. Hoping this was all worth the time. i have everything working and made test cuts. I have checked everything i know to check on the thcad-10. everything is wired 100% as manual states. As well i have changed setting in the qtplasmac gui to try and get it to 0 volts. If i put a 0 in voltage scale it will give me 0 volts. Im guessing i have a blown thcad-10 or encoder is blown. Im wondering if i cant use a tool i have for working on cars. I have a PicoScope oscilloscope to maybe check thcad-10 or encoder? I have had it for a long time and had forgot i even had it. Used it a long time ago to test a ignition coil on a car along with some other stuff. Any advise would be great! Thank you for the input so far.