[swordspider]

Hi there, quick question. I believe my laser tube just conked out on me but I want to make sure you all agree before I go buying a new one and start ripping it all out. Here's what happened:

Using a JSM3060U.

I bought this machine used and it worked well for my first few engravings. I am engraving into stone, so power settings are 100 speed and 80 power. It seemed like over the course of about 10 uses (I engrave 2"x3" sizes for about a 5min stretch) it consistently went down in power (ie the depth of the engravings kept getting shallower). While engraving a few days ago it made this strange rattling noise (where the laser tube has those coils around it best I can tell at least) and then it just stopped working altogether after finishing about half of the next etching I tried. (Like it doesn't even laser at all now, nor will it etch in a manual test fire).

So do tubes just go out like that? Clearly it went down in power over about a 40-minute stretch of lasering, but the noise thing is what throws me off. Also, looking at the tube it doesn't have any visible damage or wear that I can see. Are there any tell-tale signs? Does this sound like how a tube dies?

Greatly appreciate any help on this, thank you!

[Tweakie]

Doesn't sound like good news.

Often failure of the tube is characterised by a crackling sound of the HV anode connection arcing to the machine casing which could be the noise that you heard. The psu will only withstand this arcing for a limited period and if all has gone quiet now, when you hit test, then I would also suspect the psu.

I think you need to plan for a new tube and psu, perhaps bought together as a package on ebay.

Tweakie.

[Gadroc]

Quick question sword, what do you consider 80% power?

That machine looks to have an analog manual power control. You need to make sure you keep the milliamps under what your tube is rated for. 40W tubes should be kept at or under 15milliamps (18 max). I'm not positive on the recommended limit on your 50W tube but I think it's 18 recommended and 20 max. If you actually are running at 80% of the 30milliamp meter on your engraver you are probably actually running it somewhere at 24 miliamps or about 120%-140% power.

[swordspider]

Well, I run it at 80% in Newlydraw software. When I watch the dial with the needle it bounces up to about 10ma- the max I have ever seen is 15ma. So I think it is regulating the power accordingly.

On the power supply response- the ma needle still bounces when the laser should be firing, it just doesn't burn. The laser still has the purple light in it though, so maybe the tube is good and the psu is actually what is dead...? I assumed the tube was dead.

Any help here is hugely appreciated. The noise I heard was not a big 'crack' it was like a consistently crunching or like something with gears was grinding... after you mentioned the psu, I just checked and the fan on that is still going. I also smelled a faint burning smell, though that could have been from the laser since it was still working at the time.

Lastly, I know this is probably a dumb question, but how can I tell what W tube I have? I don't know if it is a 40w or a 50w... and the price difference is pretty extreme.

Quick question sword, what do you consider 80% power?

That machine looks to have an analog manual power control. You need to make sure you keep the milliamps under what your tube is rated for. 40W tubes should be kept at or under 15milliamps (18 max). I'm not positive on the recommended limit on your 50W tube but I think it's 18 recommended and 20 max. If you actually are running at 80% of the 30milliamp meter on your engraver you are probably actually running it somewhere at 24 miliamps or about 120%-140% power.

[Gadroc]

I assumed you have a 50W based on looking up a JMS3060U. I was not aware that Newly Draw and controller boards could laser power from the software.

[Tweakie]

On the power supply response- the ma needle still bounces when the laser should be firing, it just doesn't burn. The laser still has the purple light in it though, so maybe the tube is good and the psu is actually what is dead...? I assumed the tube was dead.

This information rules out what I said earlier as the tube and psu are obviously working.

Have you tried cleaning the mirrors and lens ??

Tweakie.

[swordspider]

Tweakie-

Thank you so much for your help, it is much appreciated. So you think the tube and PSU are still working then? I did try to clean the mirrors, still nothing. The tube has the purple lights in it, but are you saying if it was bad that it wouldn't have that? The PSU definitely tips the needle still, but there is no 'fire in the hole', so the laser just doesn't do anything...?

This information rules out what I said earlier as the tube and psu are obviously working.

Have you tried cleaning the mirrors and lens ??

Tweakie.

[Tweakie]

If the tube has purple plasma glow and milliamp meter is operating then the tube and psu are at least working. What reading do you get on the milliamp meter ??

If the mirrors are OK then Check and if necessary clean the lens.

If the lens is OK then follow the setting up procedure for aligning the mirrors.

Tweakie.

[Seelesturm]

Sorry to revive an *old* thread, but this seemed like the most appropriate place to post, and I have not been able to find any answers throughout the vast powers of Google...

I just finished assembling a CO2 laser setup on Friday.

When test firing the laser, the ground went bad and the current for the laser arced into the frame, through the stepper motors, and back to the drivers, frying the drivers. I replaced the ground line last Friday, and was able to fire the laser successfully, along with mirror and lens alignment. I got a good whiteish-pink plasma at this time, which from my research is a healthy color (versus, say, orange).

I got my replacement drivers today, Tuesday, and the laser did the EXACT same thing and fried the drivers again (ugh). The big problem, is that now the laser will not fire at all. I did a visual inspection, and could not find anything that looks like cracks or fractures, but one or two marks that look like manufacturing mishaps on the outside wall of the inner tube.

When I try to fire the laser now, the tube is silent, however the HV power supply makes a buzz, where the volume of the buzz is directly proportional to the power output. The tube does not have any output or plasma whatsoever.

Does this sound like the tube is shot? Or maybe the PSU? They are both cheap chinese models, the 40 watters from Automation Technology.

Sorry if the answer is obvious, I just want to make sure before spending more on replacement parts, and hopefully not any more replacement drivers. Im totally new to the CO2 world.

Thanks

[billieblaze]

I pretty much just experienced the same thing w/ the Automation Technology 40w tube. There goes the weekend fun, womp wahh. In my case, I have about 5-6 hours on the tube. No driver damage though.

Does this sound like the tube is shot? Or maybe the PSU? They are both cheap chinese models, the 40 watters from Automation Technology.

Sorry if the answer is obvious, I just want to make sure before spending more on replacement parts, and hopefully not any more replacement drivers. Im totally new to the CO2 world.

Thanks

[buddydog]

Well a couple of suggestions for you:

1. Check to make sure you don't have a mirror alignment problem by holding a piece of paper (Be careful with eye protection etc.) between the laser output end and the first mirror. Does it burn the paper? Yes: Optic problems. No: Power supply/tube problems.

2. Next get a styro foam packing peanut and suspend it from an 8-10 inch dry cotton piece of sewing thread. Keeping your hands at the far end of the thread and away from the machine, bring the "peanut" close (1/2 inch away or so) to the high voltage lead while firing the laser. It should be attracted to the HV lead while it is firing proving that there is at least some high voltage from the supply. This is a rough test and does not show exactly how much HV you have but shows the supply is working. You won't need to do this test if you have the purple glow in the tube since it needs substantial voltage to even get that.

3. If it's not optics or the supply then your kind of left with the tube? I always am wary when the tube cover is off. A mis aligned mirror inside the tube could send a beam in any direction so be careful. Plastic safety glasses should be fine for brief tests.