Low live voltage all of a sudden after using the pro over a year - Solved

not sure what the issue is I’m having here. The pro has been working great for the past year but today I ran into a weird issue. I noticed when I was cutting my live voltage was showing around 12v, I noticed because it was cutting terribly. So after changing consumables, there was no change. So I decided to update to 20.6, and the issue still remains. I removed the control box and made a rubber isolation in between the control box and the leg of the cross fire, no change. Disconnected the charger from the lap top, no change. Weird issue is when I do the “live voltage test” it will show 123v, then I can do the test again and it will show 30v. Seems very erratic. Any suggestions?

These are the kind of issues that scare me. I’ve been lucky that each time I had an issue it was pretty much user error. But something like this, not so obvious.

Have you read this link, maybe it’s a failure with the VIM box? Too bad you can’t just grab another one at Lowe’s to troubleshoot.

When you say live voltage test, what exactly are you doing?

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In FC 20.6 Langmuir added a “voltage test” feature. Basically you go thru a few steps that the program walks you thru to measure your live voltage, to rule that out as a possible issue with cutting issues. I am almost thinking it may be a VIM issue as well as the issue seems to be erratic. I will do some reading and hopefully hear back from Daniel soon.
I will be doing the ground continuity test

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@oneupperformance Take an air hose and blow off the Z-axis screw and lead nut, clean with alcohol and blow it off again. I fought this same issue for months and the root cause seemed to be the grime bridging continuity from the IHS switch to the lead screw. Also look at the orientation of the IHS contact screw, mine was oriented so that the IHS contact dropped into the slot of the screw head turning the screw 90 degrees helped with the consistency of IHS. (Although it did impact the initial cut height slightly)

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Interesting… I did notice to that my z axis was binding some as if it was dirty, so I sprayed it with some wd-40. I will clean it today and see if that helps the issue

Yeah cleaning the z as well and adjust the eccentric bearings. Perhaps it’s piercing too high due to binding? Don’t rule out settings either. I accidentally tabbed through a field on sheetcam once and it defaulted to something weird and messed me up for an hour until I caught it.

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I was watching the torch when it would pierce and it looked to be at the correct height as I typically cut at.

Also I loaded a program that was cutting just fine last week, and I was getting the same low voltage. So I think I can rule out a program issue at least

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*** issue has been resolved***

Thanks to Daniel for the troubleshooting help. jone, you were on the money with cleaning the z axis. Daniel recommended the same thing. So with a quick wipe down and a blow off with some air, the voltage was reading normal again. Hopefully this will help others in the future

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Thanks for the follow-up @oneupperformance !

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Good to hear. Keep that z clean! I need to make a shield for mine. I’ve had plans for a while to install a blow gun on a separate airline right above the table for a quick clean offs.

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@jone6881 hey, Allen, can you explain this idea that continuity between IHS switch and Z-axis (lead screw) causes some problems? I tried to ask about it in a post and am being severely berated for asking. Edit: I did not actually have continuity. I think I accidentally touched a probe to a mounting screw on the IHS.

@TomWS this is a second reference. How many more will it take before you lighten up?

First off let me start with I did not read the other thread (it seemed to be going off the rails), but I was having an issue with the Live voltage reading when the plasma was not firing (3-7volts seemed to be the most common). The frustrating part was that for me it was sporadic and seemed to only happen near the end of large expensive cuts (Murphy or something). After checking the troubleshooting guides I finally gave Langmuir a call and they suggested that excessive build up of dust and “crud” on the z axis could cause the live voltage to read non-zero caused by continuity between the Z axis lead screw and the IHS contact. After a deep clean the issue went away and has not returned. I did not dig any deeper other than being extremely happy to have my machine back to normal. It has been 5 months or so and with regular cleaning I have not had another issue.

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Good decision skipping that reading! I don’t always stay bent over for the whole whipping’ and certainly got drawn in there.

Thanks for taking the time to explain your experience and the problem you were able to address. I’m glad your table is working well. Be good.

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