Glass laser tube cleaning

Added by KalleP over 9 years ago


I connected up a new laser HV PSU for a friend and he kindly gave me two used laser tubes. They are impressive 80W RECI tubes. He said they were not working right. One is old and the bore shows discolouration, the other was made this year and looks new. Both of them were run with tap water and have some crystalline/limestone sediment in the cooling tube. I do not have a PSU to test them yet but they should still be gassed up, I will see if they strike with my 40W PSU or see if I can fix the broken 80W psu later..

My questions:

How much damage could the sediment cause or have caused?

How does one clean it out, do I just circulate warm distilled water though it, should I add some dilute acid or base to help the process along?

How long can one run a typical glass CO2 laser tube with NO water in it just to see if it will hold a beam?
My gut feel tells me the heat will not diffuse through the glass in less than a second or two and should be safe for a one second test every 15 minutes or so, perhaps a second per minute if the water jacket is full.

Johannesburg, South Africa

Replies (4)

RE: Glass laser tube cleaning - Added by KalleP over 9 years ago

Ahhh well.

I threw caution to the wind and made up a temporary HV cable with an uninsulated mating plug for the 'broken' PSU. Dug out some little screws for the mirror mount terminals and wired up the old tube.

Power to the PSU made the fan kick in. I fearlessly pressed the test button for half a second and had a lovely purple glow and a 6mm charred hole halfway through a corrugated cardboard. Hmmm I thought, perhaps the new tube .... Wired that one up and tried it with similar results. A tap on the button gave me a 3mm charred mark. A half second burst a 5mm carbonisation through the first layer with a pop and a flash of flame. Checked the LEDs on the PSU and all 3 came on when I pressed the button.

I have no idea what the test power lever is set to and did not connect a POT, I know the PSU I installed for my friend with the same type of controller hybrid/module raised the analogue pin from 0V to 1.6V when the water pump safety circuit was active with no wire connected to the analogue pin. I din not have a loose mA meter to hook up and did not think to use my DMM so I do not know what the current actually was.

When I get my water pump hooked up I think I must play a little more and see if I can get a reliable setup to test the power and currents.

I have a second 40W laser engraver without a tube so I will look into cutting a hole in the side and having the tube in an extension box like I have seen on some other systems. This tube 1150mm long will need a 300mm extension but I may make it long enough to take a BIGGER tube one day, just need to see what I have to do with the mirrors, the beam is going to be higher with the 80mm tube or even more with a 90mm tube.

I will have to get a second LAOS controller as soon as I get one unit working by the look of it.

The old tube is a RECI V2 80W 2011/8
The new one is a RECI W2 90W 2013

I see RECI are now selling the Z series tubes that are supposed to be even better.

If I get one of these working it will be a super deal, I spent about 2 hours with my friends gear opening the old and new PSU and testing the wiring on the laser cutter to figure out the correct wiring. One can take nothing for granted even though the PSUs use the same controller hybrid that is potted in a box with the web address but their site is not active, archived or mentioned much anywhere.

I have traced out the pins if anyone wants them I can upload a sketch.

Johannesburg, South Africa

RE: Glass laser tube cleaning - Added by KalleP over 9 years ago

I found a few sites that suggest 20% hydrochloric acid in broken Chinese.

What is the minimum clearance that is safe from the outer envelope to the metal chassis It is close to ground potential as the HV end is behind the ionised tube (and or the spiral trap). In my larger laser a 80mm diameter tube will require careful placement and even with significant cutting I may be able to get a maximum of 11mm.

The only diagram I have seen says it needs >10mm from the HV end (with the insulator cover on) from the metal work.

Any ideas?

Johannesburg, South Africa

RE: Glass laser tube cleaning - Added by Sprite_tm over 9 years ago

Fyi: I have a psu that's made by the same company and the website actually is . Pretty easy to misread that though.

RE: Glass laser tube cleaning - Added by KalleP over 9 years ago

Sprite_tm: Thank you very much for that.

It had puzzled me that there was no record of the company website, I assumed that someone had a container load of old potting boxes that they were using with a defunct company address. The Chinese are not above misdirecting people by taking manufacturer and part numbers off components and modules so I thought perhaps they were happy that the domain was dead. Silly of me to be so suspicious.

On my PSU the moulded address is behind a big cap so I could not get a better view of it and the PSU has no other markings anywhere. The replacement PSU my friend got was sold and branded by Reci and they are clones of each other but not identical except for the hybrid module inside.

My Jinan Zhenyu PSU looks just like their MYJG-80WB model, it has a test button with 2 indicator LEDs next to the control interface and an extra LED that independently monitors the flyback transformer current and lights up if the low voltage part of the switcher circuit is working. The Reci one looks like the DY10 type and it has a max current set POT that mine does not.

Attached is a image with information relating to the hybrid in common that I made mostly for myself but also others can use it to figure out connections on other PSUs that may share the hybrid but have yet another connection arrangement. Both the Jinan and the Reci website have the pinouts but we did not know the make of the old PSU until now and the Reci PSU was supplied by the laser integrator but they supplied the Jinan pinouts with it so it did not work. I opened them both and saw the common module and worked back from that and the known pinouts and then figured out what went where on the controller (no pinouts available) as they had not made a note of what wires came out of what hole in the old terminal strip.

The Jinan site also sells lenses and laser tubes if you look at the Chinese version, not for export I expect. The translation is just terrible on all the tech documents but Google translate is not much better.

Johannesburg, South Africa

jnmydy com laser.PNG View - Jinan Zhenyu Laser PSU controller hybrid (5.53 KB)