Dead in the water

[Mark Taylor2]

Well.. I killed it. My overpriced Micromark machine. I was cutting some 1/4" mahogany (med-high power, low speed, water at 67 degrees, and multiple passes) and turned to talk to my wife and knocked the power control knob to max. About a minute or less (so it seemed), something in the power supply area snapped, screamed and zapped a lot. Looks like I fried the power supply. So, a couple of questions while mentally sort out the damage....

I should point out that the tube isn't the stock "40W" as claimed (720mm) but a 45W (1000mm) from Lightobject.

1) Should I replace the tube also? I'm thinking yes... and would rather be safe than sorry.

2) The controller board.... is there a likelihood that it's damaged?

I'm just not sure what the failure mode here is....

Damage control is reporting that replacement of the parts is cheaper than replacing the machine...

Thanks for the help.

[Kelly Klaas]

I am not an expert on laser machines but I was chief engineer at a 4-radio station group I worked at for about 40 years. My advice would be to replace (or fix) the power supply first. If that fixed it then you are home free. If that doesn't do the trick and your display panel doesn't work properly then I would replace the control board. If the control panel seems to be working normally but still no output then replace the tube. I would almost bet that replacing the power supply will fix it. If there is a good electronics tech in your area chances are they could repair the power supply for you. There are only so many things that can go wrong with the power supply. They are pretty straight forward.

Kelly in southern Idaho

[Mark Taylor2]

Thanks Kelly. The PS is on order and my current plan is to swap it out first. Test the controller without the tube firing and then try the tube. I'm edgy on that part as I'm not sure if the tube took out the PS or not. I had been doing some testing near the limit of the power range (15mA max on an 18mA rated tube and a 20 mA rated PS.). The PS was definitely throwing sparks and smoke.

I read here that this isn't uncommon that swapping the tube sometimes kills the PS on the Chinese machines. So.. <fingers crossed on getting the PS soon>.

The only display is the light for the power switch and the mA meter. No bells and whistles on this beast.

[Kelly Klaas]

Good luck with it. Keep us informed as to how it turns out!

[Bert Kemp]

Yikes Mark you would be so much better off buying a small Chinese laser direct import then trying to make that thing work again. JMHO

[Mark Taylor2]

I've thought about that Bert. Maybe after tax refund time as I'm getting hit hard with house issues.. roof, tree problems, etc. Even the garage door decided to give me grief in the pocket book. Power supply price and tube price isn't bad and overall, I'm still below what a Rabbit or Boss would have cost.

That reminds me... it's a hobby and I'm supposed to be having fun.

[Mark Taylor2]

The damage has been repaired. The water pump failed (murphy strikes), the tube naturally failed with cracks and leaks at both ends. The water ran down the HV lead from the tube to the power supply and some arcing took out the control board.

The Power Supply does check good and works but I bought one with a higher rated output and a fan on it. I've replaced the water pump, the tube, and the controller and learned a lot in the process.

Now a question... I'm seeing a dime sized bubble at the inlet side of the tube that keeps coming back. I'm suspecting an air leak but not a big enough hole for a water leak so no full power testing. What is an acceptable bubble at that end of the tube? I've read that "small bubbles are normal" but is this a small bubble?

For peace of mind, I'm upgrading to a chiller and adding a flow indicator. But this bubble has me nervous.

[Ron Gosnell]

Sometimes they can be a little stubborn and hard to get rid of but my thinking has always been any bubble is a bad bubble.

[John Noell]

I have found that loosening the tube supports a bit so I can rotate the tube somewhat makes getting the last bubbles out pretty easy. Once they are REALLY gone (look out for small sneaky ones) I have not ever had them come back. My system has a flow sensor so the laser won't go unless water is flowing. FWIW, I am using filtered rain water with one capful of bleach.

[Dave Sheldrake]

Leave the pump on 24/7, even them though cavitation can cause bubbles to form. A dime sized bubble can certainly kill a fully glass tube, it usually causes the bond to overheat and the mirror/lens end to fall off

[Rich Harman]

I've been running for years with a peanut sized bubble - however the bubble is in a place that causes no harm. My point is that it depends upon the tube design wether or not a bubble is acceptable.

[Mark Taylor2]

I only use this thing a couple times a month at this time, but that's probably going to change early next year when I start doing custom cutting for people in the hobby I use it for. Fiddling with maintenance issues, while good for learning is a pain if they're ongoing.

It would appear that the bubbles are indeed coming from pump cavitation. The old pump was rated at 10L/minute. The new one (from the company that sells the cutter) is rated at 3000L/Hour (50L/minute). They "upgraded" the pumps apparently. The old one has an 6mm fitting on the output to feed to 6mm tubing. The new one has a 4mm fitting. I had to replace that fitting. I'm getting less bubbles than before but they're still there.

The tube is different than the one I replaced in design (same supplier, newer model according to the seller) and it looks like from some testing that it's more efficient. The bubbles are hanging around the lens, mirror, diode area at the non-output side. From what I gather the Chinese are upgrading their processes and designs for these tubes to stay ahead of the competition there... and with no patent/copyright protection, this might get interesting. They're pushing the government for new (and enforcing them) regs. So my 45W replacement tube is now labeled as a 45W/50W tube and is outputting 50W at 15mA as opposed to the old one outputting 45W at 16mA.

So.... long story short... Conversation with the tube seller and I'm waiting for the chiller to show up this week with fresh and larger (8mm) tubing to match everything up. Christmas present to myself.

Thank you for all the help. This site is a true blessing in it's information and willingness of members to help out.

[Bert Kemp]

Mark did you build an extension case for the new tube?

[Mark Taylor2]

I did when I did the upgrade from the "40W" that came with it to the 45W that blew. Had to as I'm not about to have a bare tube hanging out in the breeze.