Grounding issue?

hey guys, just set up my pro table when i was installing the thc on the installation guide it says to check for continuity between the usb shell and the gantry. when i do that i get 4.27k Ohms, and when i unplug my laptop i get 4k ohms. is this right? when i turn on my control box i can hear the motors buzzing and it gets a little bit louder when i plug in the usb on my laptop. i installed the plastic isolator between the control box and the frame of the crossfire also. any insight would be great thanks


Not good. Unbolt the control box and make sure it’s not grounding out to the frame. The plastic bushing are total crap. With it unbolted from frame check it again. Could be the laptop? Or a external monitor?
A ground isolation choke from Amazon may fix it.
Call or text Langmuir or text them they will walk you through it.

They actually just emailed me back with a flow chart. I’m going to try unbolting the electronics from the table and see what happens first, I ohmed it with and without the laptop plugged into the wall, and the usb cable but it was around the same reading. Maybe mounting the electronics on the wall behind the machine might work better. But I’ll test it first

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Do it one step at a time. Resolving electrical interference is part science part voodoo :japanese_ogre: :tumbler_glass:


I discovered elec interference by just rotating the cart my plasma cutter sits on 30 degrees from being straight on with table. No closer, but just rotating it a bit thru my table for a loop.

Yup, it’s voodoo I tell you!.. Hahaha! :japanese_ogre:


Do you have a ground connection to the back of plasma cutter?

If you ground out the plasma cutter it will act as a faraday cage and may solve your problem.


That I don’t have but i’ll add one.

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it is interesting isnt it… because i swear i was getting the continuity (albeit extremely faint and very high ohms) depending on whether my test leads were crossed… or how i was crouching to do it… this is with everything connected and powered on… laptop on battery, but plasma and everything else hooked up and running idle.