Never had the issue. I was hoping for ‘video’ so I could hear it…
Someone posted a diy 80 watt co2 that has a ‘band’ on the cathode end of the tube. Not sure what he can do or if it’s an indicator of another problem… seems to me the only other part here is the lps…
Have you seen this before and what’s do you think the issue is?
Here’s the thread from the Lightburn Forum, both of the video links are posted there also.
Asked for a ‘close up’ and he sent this…
A tube issue, no intent to ‘steal’ the thread… you’ve dealt with the ‘tube’ end of things more than I, hoping for some of your insight.
I took of tube lid and captured on video what happened. Without the lid the sound was very loud. I think now I have a clue what is the problem These things are very very dangerous. I am glad I started the test with wireless mouse from the outside of room.
About arching:
Thank you for confirming. I did a little bit of research and found three reasons for arching:
dead tube
poorly connected anode
poorly isolated anode connection
Actually I do not think, that is because of dead tube (maybe now is dead), but rather because of second or third option. I will explain:
When you buy stronger laser (80W for example), you have some kind of connection mechanism to anode/cathode cable on tube covered with electric isolated cover, or, more conveniently, a piece of cable coming from tube and all you need to do is just connect two cables. This is not the case with 40W. From the tube comes out metallic pin about half centimeter long and that is everything. You have to proper connect cable to the pin (you can not solder, because you can crack the glass with high temperature). So you wrap the cable around the pin and use silicon and little peace of hose from your cooling system to cover it up. This can be fine for like 100 volts, but for 20k volts is sounds very irresponsible for me. I know, that K40 is piece of junk, but in my opinion, this is serious security hazard.
So I did my best co connect the anode and it seems like it was not enough. I actually secured the cable to the pin with superglue before applied silicon, maybe that is the problem. Today, I will try to clean the pins with acetone and connect the cables once again.
I would not use superglue; it isn’t conductive. I’ve seen small cable ties recommended for holding the wire to the post, fitting inside the silicone tube after the end of the cable tie is trimmed.
Voltage this high does not need a gas-tight connection. Wrapping the wire on the anode pin is the normal way of connecting. That is followed by a silicone sleeve which you fill with HV silicone.
I’m still confused why he sent us videos of a different machine in the first two with a totally different problem.? This kind of communications makes me uncomfortable…
I cleaned pins with acetone, rewired cables, secured with zip ties as @mcdanlj recommended, put some silicone, then silicone tube and filled the tube with silicone. And after firing up “nothing happened”. So, the tube is dead, but I also do not have arching anymore, and that is important to me. The likely culprit is superglue, which probably did not allow current to pass trough the connection and of course, poor isolation. Now my connection looks more professional.
I actually bought K40 because I like tinkering. I changed or upgraded almost every part in this machine. But from the beginning, I was afraid of changing laser tube at the end of its life. Clearly, my concerns were right. I already ordered new tube and now I know how to replace it properly.
As you figured out, most likely when you put the superglue on it the very thin liquid seeped under, in and beneath the wire and connector. And the gases given off when drying could also coat anything which didn’t get superglue on it. Live and learn right?
So now that you have completely cleaned the laser tube pin connection, did you also cut off the end of the HV wire to the point where there’s no superglue in the twisted wire bundle? It probably wicked into the wire a bit because that what thin liquids do.
IIRC(If I Remember Correctly) others have stated you more likely to have damaged your laser power supply rather than the tube by powering up the LPS with such a poor connection and arcing to the grounded case. At least I think that’s what’s been warned about but hopefully someone can confirm.
Ya, I looked at the beginning of the thread and this all started with a new tube installation.
And while I know you all here are fantastic at this stuff MY first response would have been to the tube manufacturer after hooking it up and hearing it hissing but not working. On 2nd thought, I would have opened the cover and looked to see if the tube was firing before contacting the tube reseller.
today new tube arrived. Actually, I bought a set containing tube and power supply unit. At first, I wanted to replace only PSU to see, if the problem lies in tube or PSU. But, when I saw dirty first tube (photo below) and realized, that I can maybe destroy new PSU with arching, I decided to change both just to make things working. This time, job was quick and easy and I had a good feeling of it. After firing up, tube was working as it should have.
In my opinion, this whole problem gives me a good experience how things work and how to deal with them. It cost me one laser tube (about 90€), but I don’t regret it. As I wrote in previous comment, I probably destroyed first tube using non conductive superglue.
Thank you for the help, I very appreciate it.
To learn a bit about what’s all over that tube, try this experiment:
get a large glass jar you can throw away and clean and try the inside.
rub your index finger on your face near your nose to get a little oil on it and then press your finger onto the inside of the jar in 2 or 3 places.
make a little bowl out of aluminum foil, place a few drops of super glue in the foil bowl and then place the jar over the bowl.
24 hours latter see if you can see your finger prints on the inside of the jar.
IIRC CSIs use this trick to get fringer prints off of things.
It will also show you why you would never want to put superglue on anything or around anything which might be sensitive to the vapors given off while curing.
These things are very very dangerous. I am glad I started the test with wireless mouse from the outside of room.
