Laser HV wire arcing and hissing despite insulation

Community Laser Talk
1

Hi everyone!
After you all helped me solve my previous laser problems:

i got a new cloudray tube and power supply and it was working terrifically! but one morning we turned it on and the laser wasn’t firing, and instead making a loud arcing/popping sound.

Nothing physically changed or moved around between when it was working and not. Just like 12 hours had gone by.

I looked in the back and saw there were sparks arcing from the HV laser connector wire and the bed.

i recorded a couple videos of the setup at this link
https://drive.google.com/drive/folders/1WpM4hfHYlIUv1Vl0peil4yuGogFxD2Xs?usp=sharing

it looks like somehow the electricity is arcing through the High Voltage connector.

when i looked inside i could actually see sparks coming from around the HV connector.

so i insulated it more, resoldered it, and even redid the insulation inside the HV connector, and it was still making some sparks, and then i even added a big PET bottle around it as insulation to make sure it couldn’t arc, but then it would still make a fizzing sound

it seems like this is an overkill amount of insulation (and it used to work totally fine with the regular insulation it had), so it seems like something else must be wrong, right?

sometimes when it is insulated in the bottle, the tube will briefly glow pink for a short time, but then go back to fizzing. So some electricity is able to go through the tube it seems

anyone got an idea of what is going on here, or have any troubleshooting tips? what might be broken?

I messaged cloudray, and they messaged back they would get back to me, but it’s been like over a week now.

thanks for your help!

2

What are you using to insulate? Materials that work fine at 600 volts and lower can fail dramatically at 6KV and greater.

1 Like
3

yeah im doing what most everyone i can see is doing on connecting lines.

I solder the HV wires, heat-shrink, have tried a little bit of hot glue or not, but then put the HV plug thing over it, and then added a polypropylene or PET tube around them.

most folks just stop at the HV plug, so this seems like overkill, but it’s still leaking it seems.

4

Except, perhaps, ambient humidity.

Or progressive deterioration of the junk you used in the repair.

Per your previous thread:

I snipped out the bad part and used a high voltage connected salvaged from the old power supple, and then i put everything in a silicone tube, so seems pretty well insulated now!

Pretty much everybody told you not to do that, for very good reasons. Now you know why.

Stop screwing around.

You must replace the entire run of HV wire with known-good HV wire, properly connect it to the tube, use known-good HV connectors, and properly insulate it as needed with known-good material.

You may or may not have destroyed another power supply.

5

Start with this wire…
" https://www.amazon.com/10Ft-30KV-18AWG-Voltage-Rubber-Silicone-Telsa/dp/B0747DYJ7X?th=1 "

Paint the frame where the arcing occurred with about 3 coats of this stuff…
“https://www.amazon.com/Star-brite-Liquid-Electrical-Tape/dp/B0000AXNOD/ref=sr_1_9?crid=2XK4BRURWAS8N&keywords=high%2Bvoltage%2Binsulating%2Bcement&qid=1688318638&sprefix=high%2Bvoltage%2Binsulating%2Bcememt%2Caps%2C97&sr=8-9&th=1”

It is what you can’t see that is giving you grief. If you can’t get items like these from Amazon, source them Google or locally.

6

It’s less “screwing around” and more that our lab is in the rainforest in Panama and not super easy to get special items that quickly to :slight_smile:

7

Will try to find a replacement wire for the whole thing and see if that helps :slight_smile:

8

Well, that definitely explains the “humidity” thing!

For example, the breakdown voltage of dry air around here is about 1 kV/mm, while your air might withstand barely half that. That means you must take precautions nobody else (including the laser manufacturer) thinks necessary.

Every arc destroys the wire or connector it originated in, because the arc track contains conductive debris: carbon / silicon / dirt / whatever. That damage cannot be removed or repaired: you cannot reuse a failed component.

If you can find a local neon sign shop, they may be able to get you up to speed with high voltage wiring techniques and components.

There is definitely a time and a place for improvisation, but high voltage equipment is not the place for half measures that can kill you stone cold dead.

You should order another power supply, because you need a spare on the shelf for occasions like this.

9

IMHO… I think you have a bad tube or a faulty cathode connection… I know it’s a new tube…

When this occurs, the hv will greatly exceed the maximum voltage. An lps increases voltage until the tube lases… if this doesn’t happen the voltages can exceed 30kV rendering most of this insulation useless.

The connectors should be OK up to about 30kV… I’ve cut and spliced them on my machine with hv connectors like yours… I don’t solder mine, but at these kinds of voltages, I doubt I need to…

image
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@ednisley is correct about a hv punched hole in the insulation. I’d double check the connectors themselves for an carbon trails… It’s almost impossible to determine a hole in insulated wire… it can be micro sized and virtually invisible…

In the end, all or any of these systems can and do fail… Sometimes it’s a new tube, sometimes a faulty lps…

I’d put money on where I’ve see the most failures and that’s at the tube, itself or how it’s cathode is grounded…

Double check your cathode path… if this is open, you will see similar results…

Good luck

:smile_cat:

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Update, i made it out to the city today a d found a aign place that had HV connector wires.

So I just replaced the whole HV cable going to the power supply with a brand new cable and it still has the same problem (just hissing and not firing, i haven’t let it arc).

Should i try to replace the red wire connected to the laser tube? That seems a bit trickier. Also was there always this white goo coming out of the laser tube connection point?

PXL_20230703_202352665
PXL_20230703_2023526651920×2550 178 KB

I disconnected and reconnected the ground wire too just for good measure, but no difference.

Is there any good way to double check the factory connections to the tube?

Cloudray still hasn’t gotten back to me, usually they have been quite responsive :confused:
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11

It still sounds to me the lps is generating hv to cause the tube to lase, but it’s not occuring… That would indicate the tube has a problem…

Low chance of it being tube connections… I’d assume the anode (hv end, as in the photo) is ok…

If it goes through the insulation, it would definitely go across one of these poor connections…

I think you need to sit tight and wait for your vendor to advise you about a tube…

I know of no way to check these without the proper supplies and test equipment…

Check over the tube visually for any kind of deformation or crack that would allow the gas to escape.

After that, I’m not sure what to advise you… it’s unlikely that the hv from the lps is too low to allow lasing, so it almost has to be a failure with the tube.

Hopefully the vendor can assist… I think we’re at the end of the road here :crying_cat_face:

Maybe @ednisley has a suggestion…

Keep us informed…

Good luck

:smile_cat:

12

Yeah, this is what I’ve been suspecting. Will keep y’all posted!

13

I have to jump in here…
I didn’t have any arching that I know of but when I started the machine I had no “burn.” Opened the back of machine today and found the ground wire insulation had melted plus the HV connector, which had been wrapped in plastic electrical tape, was burned off partially. (THEY WERE LAYING ONE ON TOP OF THE OTHER) Cleaned all that crap off, wrapped the bare ground wire with tape and temporarily used a wire nut and several layers of tape after cleaning the ends of the HV wire. Don’t at the moment have a HV connector so I done this to see if I had operation of tube. It fired as normal with the Pulse Button. The ground wire was isolated from metal case of machine with nylon standoffs. I replaced the ground into the same fixture.
Will need to see if Grainger has a HV connector after the holidays.
I am going to isolate the HV cable also.

14

Cloud Ray just got back to me and they say that their technicians say this. Looks like there is a gas leak in the tube and they are sending me a new tube. So bummer, but overall resolved:)

15

It was pretty indicative of a tube failure… hence the suggestion to see if there was anything physical you could see with the tube…

Good luck… let us know…

:smile_cat:

16

it was definitely the tube that failed

cloudray sent me a new one for free

but then that one arrived shattered, hahahaha
and so they sent me another one for free

and then that one seems to work so far!

definitely was the tube failure, not any kind of secret leaking uninsulated wires
:slight_smile: