Centroid Community CNC Support Forum

Hello Tamar I've checked out the reports from your THC when you ran the THC Calibration Job. Looks like the TX Board hasn't been able to read any good voltages yet. It doesn't look to be 60HZ noise but a constant high voltage that is flatlined. I would like to TeamViewer into the machine if possible. I can better see any stray voltage the TX board is picking up. Photos of how the Cabinet and THC boards are wired is needed also. You can Contact me via Phone at (814)571-1043 or mccullochjoey@gmail.com and we can set up a meeting. Really need pictures so we can confirm the wiring from the Plasma box thru the THC boards and then the Acorn to the drives and motors. I'm Available at any time you are.

this is my self build plasma cnc table.
nema 34 hybrid servo motors on all axis.
plasma source - misnco 105AL (copy of hypertherme 105)
its has voltage divider of 1:20 / 1:50 / 1:100
its set to 1:50

if i measure the voltage from the 1:50 divider while cutting at 1000rpm 85A 6mm mild steel at 3mm cut height, what should be the voltage while cutting?

Did you do the TX and RX voltage signal communication bench test that is outlined in the Acorn plasma manual? This is very important to verify the voltage readings BEFORE you start cutting anything.

Do you have the manual for your plasma cutter? The voltage should be in the manual in the cut charts. Since the Acorn Plasma has not been tested with that plasma cutter it's hard for us to tell you what the voltage should be but start with the numbers in the cut charts.

If that is truly a Hypertherm clone then your cut height for shielded mild steel cutting should be 1.52mm not 3mm. The pierce height is 3.8mm. According to the Hypertherm manual for my Powermax 85, cutting 6mm steel at 85A shielded would have a target voltage of 123 volts at the tip. So your 50:1 voltage divider output should be 2.46 volts. But that's not a Hypertherm machine. This info should be in your manual.

I did not do the TX and RX voltage signal communication bench test .
I've measured the voltage coming from the divider at 85A at 3mm cutt height and it 65-67 VDC

I also measured the raw voltage while cutting, its 380V

Hello Tamar. The TX board can only handle 0 to -10V. If the Divided voltage is really 67Volts that will not work with the TX Board. I would disconnect the divided voltage from the TX Board and perform the THC Bench Test. Just hook a battery to The TX Board like you would the divided voltage and run the THC_Benchtest job to confirm the TX board reads the correct battery voltage and has not been compromised. (this procedure is covered in the Acorn Plasma Installation manual) https://www.centroidcnc.com/centroid_di ... manual.pdf I've Attached the Schematic for the Black THC Board bench test. all plasma schematics are located on the schematics page. here.
https://www.centroidcnc.com/centroid_di ... browse.php https://www.centroidcnc.com/centroid_di ... browse.php
Hopefully you find the TX Board has survived so far.

380V Raw Arc voltage seems way to high. Lets just say it was 380V. 1/50th voltage divider from 380V is 7.5 Volts. You measured 67Volts from the divided voltage output, which is more like a 1/5th voltage divider. That is also very high and is not expected. Make sure the raw and divided voltage is measure with a scope or meter that can handle the high frequency noise coming from the Plasma box. The voltage measuring device your using may be not working correctly for this application.

Neither of those numbers makes any sense to me nor are they even close to Hypertherms numbers. At the voltage divider set to 50:1 the highest value you should see is about 3.5 volts according to the cut charts from Hypertherm. Also according to the manual the max raw voltage from the Powermax 105 is 175 volts and this is cutting real thick aluminum.

I'd suggest reading the Acorn Plasma install manual again and perform the required tests to confirm you have everything wired correctly. Also read through your plasma manual and verify voltages. The Acorn Plasma has never been tested with your plasma cutter. The only reliable unit tested is the Hypertherm. They tested others but the voltage signals were not as clean as Hypertherms.

Sorry for the same reply but Joey beat me to it.

hey again, ive connected battery of 9.5v and tried the bench test and its reading 10v.
it was odd for me that it was reading 10v it a bettery of 9.5v, so i disconnected the battery and tried again the bench test and it was still reading 10v.
do you think i killed to board?

ive noticed that only one led is on, is it supposed to be like this or the two leds need to be on?