Yes do a straight line cut and look at what your live volts are during the cut. There is likely an issue with your THC sensing.
@theworkshope Here’s a video first of a straight line cut on 1/16" mild steel, but using THC, just prior to my panel attempt. Then of the initial part of the panel cut I couldn’t make it through. As I said, I then switched to post processing small clusters of holes to see if those would work, which they did. I did measure the length of cut and all cuts seems to be stopping in the 9-12" range, for what that’s worth. I have not done long cuts on thicker material without THC.
@langmuir-daniel I’ll do a straight line cut and get a video of my live volts during the cut.
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Put your clamp on your workpiece
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On edit. Gotcha… will try that. Thought at first you meant to clamp the item down. Tracking!
@langmuir-daniel I performed 3 straight line cuts. All errored out before completion. Seems all have some voltage showing before cut, then Live volts drops to zero during cut, then Arc Voltage Lost error screen, then some voltage value (other than zero) appear again. I let the videos run after the cut stopped in case those voltage values are useful.
First of all- i wish EVERY customer would provide us with videos exactly like this. It makes our job so much easier!
With that said- you are showing zero volts in Live Voltage during the cut and that is the reason that you are getting the arc voltage lost error. The THC is not sensing any voltage (which is incorrect because there is voltage as evidenced by the arc being on) and that is why its throwing the error.
The good news that its likely going to be a very easy fix. Based on the fact that you get a small blip of voltage after the arc shuts off, I am guessing that you have the polarity of your arc voltage leads reversed. How is your plasma cutter wired?
If its not that, it will be something simple. Here is a troubleshooting guide that we put together for this exact issue: LS-THC Arc Voltage Troubleshooting Guide
Some other simple things: make sure you don’t have electrical continuity between the USB shell (part that pokes out of the electronics enclosure) and the slat bed both with and without the USB cable connected. If running on a battery charger, make sure to use a 3-2 prong adapter if your charger has a third prong.
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is it wired for Divided voltage thru the CPC connector or Raw voltage?
I’m running my Cut60 on DV via the CPC with no issues. it’s just odd others with the Cut60 are having issues.
Thanks on video!
I wired my plasma cutter in May, and haven’t changed it, as follows.
Crossfire Pro CNC to PrimeWeld Cut 60 CPC connections:
Plasma START/STOP (either solder wires from existing cable or splice in two 22 AWG wires):
Pin 1
Pin 2
THC Voltage Divider:
RED wire ------------------------------------------------ Pin 4
BLACK wire -------------------------------------------- Pin 6
I went through that troubleshooting guide in late May when I was having issues. Got about 80% through it with all checks good when I tried an extra loop on the USB cable and an extra ferrite choke. But I’ll double check everything including the USB shell.
@nicaDd CPC, as per above. It ran fine in late May after I resolved my initial noise issue.
So I’m assume you have the THC box wired like below? Only asking because Daniel stated that you’re not getting any voltage readings so it could be a mix up or failure in that area.
yeah, I thought exactly the same. typing words and paraphrasing only gives a tip of the iceberg vs actually getting corraling all the data, setup, etc of a dynamic situation. I also work on troubleshooting cars online so the challenges are similar. good job with the audio/visual description, Airdog!
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Here’s a pic of my setup. Looks like yours @nicaDd. Still, if I get no joy checking USB continuity, and troubleshooting guide I’ll double-check wiring inside and routing out of CPC. My thought is it’s not a polarity issue since it was running fine a couple of months ago. I think maybe when I pulled the main board to lop off the L1 inductor I might have induced unwanted continuity? Not sure, but I’ll run all this to ground over the next few days.
Thanks all for the help!
if you haven’t yet, also do the voltage check from each end point. maybe the wiring got loose inside the CPC connector?
@langmuir-daniel Added you to flag it for higher priority
In my completely uneducated assessment, I suspect strange things are afoot . . .
Thanks- were looking at it now.
Ok we have reviewed the video. First thing, can you verify that the reference voltage is actually zero? We have never seen anyone actually get a non-correct reading for reference voltage.
Second, it is incredibly strange that merely swapping the leads when measuring the voltage out of the torch fire cable would yield any difference except a sign change on the reading. When you swapped the leads the reading remained negative but less negative than it was. It leaves us skeptical as to what is actually happening on the primeweld voltage divider board. The fact that you are getting a negative voltage out of the plasma cutter would explain why you are always seeing a hard zero on the live voltage DRO.
I’d recommend using a small DC battery (like an AA battery that is 1.5 volts) and wiring it to the THC port on the electronics enclosure. You should see nominally 108 volts or somewhere thereabouts on the live voltage DRO. If you do, then i think that the primeweld divider port would become suspect #1. If it is, your best bet may be to wire to raw volts.
I noticed on the C2 reading you appear to be reading off the first pin from the left, marked D13. The image accompanying the trouble shooting guide leads you that direction, but the reading should be taken off the third pin from the left. I marked it on a screen grab from your video. Just FYI before you take that reading again. Disregard if the video tricked me.
@langmuir-daniel I checked the voltage again 3 times, got around 0.020 volts each time. Fourth time moved my GND lead to the top of the solder joint on the GND pin and Voila! . . . 4.084 volts.
Did the AA battery check, and you nailed it. Got between 113 and 115 volts on THC Live Voltage DRO on 2 different checks. I’ll talk with PrimeWeld and go raw volts in the meantime.
@Jemejia Good catch. I went back to take pics after I did all the first round of troubleshooting readings to document them. After taking readings above this time around, I remember I was getting around 0.020 volts. Must have brain-farted and focused in on the bold D13 on the diagram when I was multitasking trying to get the pics… and 0.015 was close to what I had been getting. Note that I didn’t attempt any pics for the C3 check… to darn hard!
Again, thanks a ton for the help Daniel, et al!
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NOTE that there are two 100K resistors built into the Prime Weld CUT60 machine before the connector pins for “raw arc voltage” this was an issue when I was setting-up my THC3T–02 as there were also two 100k resistors on that board, effectively summing to 200K circuit resistance. I therefore had to bypass (jumper) the two resistors on the THC3T board to get the volts to read correctly. Don’t know if this is relevant to your situation, just thought I would throw it out there.
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Good luck getting back to cutting. I hope your customer service experience with PW is as good as mine a few months back. BTW Those markings are easier to see in your video than they were in person. My 56 year old eyes and not-so-steady hands struggled with this troubleshooting. I didn’t think I would ever get both probes on the correct pins.
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That is good news- I am confident that wiring up to raw voltage will make your system work great.
Well, I read all up and made my notes on tying into the system for Raw Voltage last night. Armed with your resistor info @Cletus I called PrimeWeld this morning. 30 sec phone call, they’re shipping a new machine out today, swapping for this one with apparent bad voltage divider board. I’ll now know what to watch for if it happens again. Hoping I have the same continued success as you have been @nicaDd. And you were also spot on @Jemejia PW customer service was off the charts phenomenal and easy!
Finally, thanks for working through all this with me @langmuir-daniel. I’m learning a lot! 
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