THCAD Environmental Fluctuations

tommylight wrote:

thefabricator03 wrote:

Rod, What do you think of this filter, www.jaycar.com.au/240v-ac-emi-filter/p/MS4001.

No need for that, you have one in the UPS, even the cheap ones do have one.

Understood, But if there is a source of noise, it could be the UPS....

Yeah I will try a new power supply for the THCAD. I have been using this to power my THCAD, www.jaycar.com.au/dc-to-dc-step-down-vol...rter-module/p/AA0236

I think its premature to blame the THCAD at this stage. It might just be reporting what it sees.

Yeah thats true, Maybe its an issue with the plasma unit. I will do some testing.

I'm not sure where 40 deg C lies on the real temperature scale (F), but all last summer here in Texas where it regularly is 100F + my THCAD gave zero issues. I second the idea that it may be the power supply.

Ok I did a bit more testing on this issue as its happening every time we get a really warm day,

Today when the issue happened I unplugged the Hypertherm CPC port and the voltage still fluctuated. I put a multi meter on the THCAD output and measured a steady voltage that did not fluctuate.

I took this video,

Does anyone else have any ideas of what I could try next to troubleshoot the issue?

Would you like me to lend you a THCAD so you can test by swapping out?
Send me an email and I can express it down tomorrow with TNT.

thefabricator03 wrote:

I put a multi meter on the THCAD output and measured a steady voltage that did not fluctuate.

That test is not really helpful. The THCAD outputs a frequency which is probably seen like a PWM voltage with a normal analog voltage meter. If you have a frequency counter on your multimeter, it would show the frequency but its probably fairly heavily damped. But there is no real need becasue the encoder velocity in halshow tells the story. Its jumping all over the place. It should be fluctuating around your zero volt calibration frequency (the Plasmac Offset). Thats usually around 3800 and that is where I saw it (some of the time).

I think by disconnecting the CPC port, I think you have confirmed that the fault lies in the frequency output part on the THCAD. The whole idea of using a frequency is that its more immune to electrical noise so its quite strange.

I'm not understanding your circuit. From memory your THCAD is in your control panel so you should be able to power the THCAD from one of the 5 volt signals on the 7i76e provided for that purpose.

Yes, normally you would supply the THCAD's 5V from the 7I76Es encoder connector
Any other source would compromise the noise immunity somewhat.

The errors could reflect a bad THCAD or perhaps an interface issue.

Is the 7I76E encoder input jumpered for differential mode and both
THCAD F0 and /F0 connected to the 7I76Es A and /A inputs and THCAD
GND connected to encoder ground?

Ideally: