Thank you very much!
I do have and know how to use a multi-meter. (I design and work with electronic systems as my day job).
I have taken all the precautions before inspecting things as well (letting the cutter sit, shorting the high-voltage lines over a resistor - and then reconfirming with just a heavy wire shorted to ground) before touching anything, making sure the unit is disconnected from mains, Laser UV safety goggles, etc. (I got a nice jolt from a HeNe laser supply I was playing with from one arm to the other back in my teens and did not enjoy that - suffice it to say I learned a lesson in due diligence.)
Thank you for your response!.. Short Answers:
- I do not see any cracks and no water leaks
- Coolant: Tap water, but was just for a test (in the past I bought distilled water)
- Arcing from below the Anode insulation to the edge of the cutter housing
- Tube is about 6 years old, with less than 3-4 total hours of use on it (hasn’t been used in ~5 years)
- Never run above 50% (I would guess My average was around 30%)
- The only out of the ordinary thing is that it’s been sitting unused for a long time.
My disappointing but leading theory, based on some forums I’ve read, is that the tube may just be dead. I purchased the cutter sometime in 2016… RARELY ever used it. The most use it got was a few test engravings here and there and then about 2 total hours of cutting of some thin, dense-foam sheets (I know… toxic and leaves residue on the optics :-() that I’d estimate, based on the position of the un-marked power knob, was no more than about 30% power (There is an onboard analog ammeter, but who knows how accurate that is.) Other than momentarily test-firing the laser at higher settings, I don’t think I have ever gone much higher than that. (I actually did draw a line by the knob for the ~30% setting that I was using at the time.)
I moved in late 2017, the laser came with me to our new house and has been sitting in the basement untouched until last week when I decided to dust it off and set it up.
For the test (I was literally just testing to see if it still worked), I made sure everything was clean, powered it up, ran regular tap water through the cooling system and hit the test button for a split second. There was nothing. I raised the power knob up to my marked position and still nothing… a little higher and the tube started to excite. (Purplish glow, high pitched “scream” sound.) I had a piece of paper under the head to see if it would make a mark and it did not, there was no laser.
I raised the power a bit more and momentarily pressed the test button a few more times… on the last press (probably at round 60-75%, I heard the “snap” of an arc. (I didn’t see where the arc came from at first as I was standing in front of the machine. Powered everything down, took a look at the power supply and high-voltage wires for any obvious damage and did not see any.
Standing off to the side of the machine, I repeated the test with the exact same experience and when it arced, I saw it come from below all the insulation / silicon on the Anode terminal up to the edge of the laser cutter housing. A few more subsequent tests resulted in the same. Not wanting to burn out the power supply, I did not press-and-hold the laser test button, but pressed it momentarily and repeatedly - each time, the gas would excite on the first two or three tests and arc on the third or forth. It seems like there was voltage potential being built up in the process.
Thought I did not see any obvious disconnections on either the anode or cathode wires, I did detach, reattach and attempt to re-insulate the anode and the result was exactly the same.
I have been googling around the web, came across several message boards talking about insulating the connections but also found a few comments (as I did here) saying that the tube is likely done for.
If that is the case, my question would then be, for a machine like this, is it worth trying to replace the laser tube (I don’t know what they cost) or should I just scrap it, use the steppers for some other project and consider buying a new cutter down the road.
Thank you both for your time and advice!