Laser tube issues...

[Gene Uselman]

I have been out on a two week Covid vacation and just getting back a few hours a day and the laser quit firing during a cut job for one of the shop people and now will not fire at all. I think it might have run low on coolant, I added a gallon [this is a CW6000 chiller for two tubes so it holds a lot of coolant]. The tube has a large bubble of air in it which I cannot get out- I re-plumbed the hoses with 3/8", eliminating the original cabinet setup which was 5/16" inside. The tube is a strange pink/purple color from end to end all the time, not just when firing and the mA meter indicates the HV power supply is giving the tube current. This tube is less than a year old and I am sure that we caused the failure- not a natural demise. Looking for any advice before I order a new tube.

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Tube 11.3.21.jpg

[Pete Cyr]

1. do you have a water flow interlock switch - if so the system should not have fired if there was no flow.
2. I f you do have a switch - try jumpering the switch (short the connection) to make the circuit and try a pulse - if it will pulse then the switch has failed or is clogged preventing flow...which prevents the switch from completing the circuit
3. Check the power supply to be sure it is working...lights, fan, fuse, etc,
4. Make sure you have no door switches that have an issue (jumper them as well) 9papaer clips cut and bent into a "U" to fit make a good jumper

5. If you have not discovered the issue by the time you got to this step - it is time for Beer and help from someone else - sorry

[Marian Scheja]

Hey Gene,
sorry fot the dumb question, maybe its just to late here.
In your picture the tube on the rear end of the machine seems to be filled completely with coolant.
Is this correct? Is it the way it should be? What kind of tube is it?
I have never seen a co2 laser tube where tube is filled al the way with coolant and the "air bubble" sits on top of the (outer) glasstube (only inside the coolant tube).
Imho in the outer glass tube there should be circulating CO2 gas and not coolant. The coolant is only in the coolant tube surrounding the (purple) beam tube as well as the mirrors (not all types). The purple stuff should be a catalytic to extend lifetime.
If there is a crack in you tube, this would explain the picture and your loss of coolant and no lasing.
I hope i am wrong.

[Gene Uselman]

Thank you gents- the water protect from the chiller is hooked to the HV power supply and when the chiller is off, the pulse shows no current as expected- when the chiller is on I get a current reading on the meter as normal. I now suspect that the glass enclosure failed in some way as Marian pointed out- the outer glass tube should not be filled with water. I switched the two tubes and I now have the laser firing when the pulse button is pushed.
Marian- the second tube was not hooked to the chiller- it was dry. After switching the two [ the Reci W6 is one of two that I have with faulty beam patterns- the beam has a 'hole' in the middle and cannot be focused well enough to work on the far corner of the 4x6 foot bed] the tube that just failed was a SPT 130w tube with a good beam pattern. This whole tube problem is getting overwhelming...
Anyway the Reci tube weighs about a third of what the SPT tube weighs with a gallon of extra coolant. I thought that we had run the tube dry as the coolant was a gallon low in the chiller, but the power supply was still showing current [IE the water protect circuit was still functioning] so I am thinking it was an internal failure of some kind.

[Pete Cyr]

Narrowing down the defect is good - having any defect is bad - sorry, i am sure tomorrow will be better.

[Gene Uselman]

I have been emailing Marco Wong from LightObject about the tube and he thinks it may have been thermal shock that broke the tube internally. The more I think about it, it makes sense. He has been with LO since I first started 'lazing' and I consider him a very knowledgeable person. I bought the broken tube from him SPT and he no longer sells that tube but recommended a GSI 130w tube that I am going to order today.
I googled heated laser chillers [who knew they existed] and LO sells two different chillers with built in heaters [he did not try to sell me either of them] and I will DIY something to keep the coolant to a minimum temperature. I am in frosty Minnesota and the temps on a cold night will break a beer bottle.

So- another bad 130w laser tube... maybe I will start making floor lamps from them- they are kind of interesting to look at.

[Dave Vigness]

Gene,

Just putting the finishing touches on my DIY heater for my 5200 An aquarium heater down the fill tube and a pair if thermo controlled relays. The TopFin heater at petsmart, or was it petco? Take the rubber ends off and it slips down the fill tube.

I'll get the info posted to my Google Mod Page in the next few days.

[Gene Uselman]

Thanks Dave- sounds like a very good thing. Gene

[Dave Vigness]

The hardest part was figuring out how to energize the pump and not the chiller. Since my 5200 had a switched neutral, it turned out to be fairly easy.

[Dave Vigness]

Got it posted on my Google Mod Page. There were enough pics and the accompanying Word doc that i did a separate folder at the top.

https://drive.google.com/drive/folders/ ... sp=sharing