THC Troubleshooting (No resistance)

I have a Razorweld 45 and a Pro table. It was cutting fine until about a month ago and the THC now does not work. Error message states that I am not receiving a live voltage signal from my Plasma Cutter to the THC module. I went through the THC Troubleshooting Flow Chart and got down to the ‘Remove the USB cable from the electronics box and remove the work clamp from the slat bed. Measure the resistance. Is it still less than 10,000 OHMS?’

It is not reading anything. Is that an issue or is it supposed to not read any OHMS? Any help would be appreacited!

When you say it is not reading anything is it saying OL or over limit or infinity or something like that? If so you would answer NO to that question on the flow chart and keep testing as directed.

@ScottNH It is just reading ‘1’, as if it is not reading anything. Is that an issue that it is not reading anything? Or is that considered, ‘Yes, it is reading less than 10,000OHMS’?

What does it have on the screen of the meter when you have the 2 test leads touching each other? And then what does it say if you separate them? Pictures are worth 1000 words…

Image 1 is with the USB plugged into the computer and the ground clamp attached to the table.
Image 2 is with the USB unplugged from the computer and the ground clamp detached from the table.

I’m not familiar with that meter can you show me what it looks like when you hold the red and black leads about an inch apart?

What type of computer are you using desktop or laptop?

Can you repeat the test that you did in image 1 and touch the slat that the work clamp is on (it is not a ground clamp, I know that might sound picky but it is actually the positive side of the circuit) I want to see if it ends up with the same resistance. It probably will but let’s see. There are other paths for this ground loop to occur through the z-axis circuitry.

This is an image of the red and black touching

2nd image I uploaded at the top of this conversation is what it reads when I hold the red and black 1" apart.

OK so it reads 1 for infinite resistance. So answer the next two questions I had and we can hopefully sort this out now that I understand your meter.

I normally use a Windows desktop and was using that when I first encountered the problem. Tried my MacBook (with it using battery power) and still having the same issue.

I repeated the test I did with image 1, but had it on the slat that the work clamp was attached to, and it read the same resistance- 1846 OHMS.

Not sure if this matters but when I test the resistance with the work clamp off the table but the USB still plugged into the computer, the meter reads 1. But, if I test it with the work clamp on but the USB off, the meter reads 1846.

So it’s not completing the circuit via the computer. I would go back to the flow chart now and start at flag 2 and run those tests.


never mind? Did I miss something?

@ScottNH I also emailed Langmuir about the issue and they told me to go through some steps and I think I found the problem- just don’t know how to resolve it. I disconnected all the cables from the elctronic box and plugged them in each at a time and measured for resistance. Everything checked out but when I plugged in the THC cord and measured the resistance, it was not reading infinite resistance, but was reading the 1865 Ohms. Would you happen to know how to resolve this issue? Thanks!

When you say THC cord do you mean the cable that goes between the VIM and the control box?

Yes, correct. Langmuir had me separate the electronics box from the frame and do all these tests and the only cable that gave me a resistance was when I plugged the THC cable back into the control box.

can you post a picture of your VIM with the cables plugged into it? Also when you “unplug” the THC cable are you doing that on the control box side or the vim side?