laser stopped cutting

[lukahr]

Hi

I have laser machine 40w with lets say max 10h of working, i was cutting some work and after machine ended things get weird. Machine doesen't cut anymore, i have checked laser tube for any cracks or anything but it seems ok, but when i measure mA on laser tube it shows max 1mA even when i have 100% power. From 0-10% power current changes from 0-1mA but from then on to 100% it stays on 1mA, is psu unit dead? or what would be cause for that.
water flow is good and cooling is working normal, everything else is working as it should only laser beam doesent come out of tube. When ampermeter shows max current 1.2mA there is visible plasma in tube but very weak. Shouldn't there be at lease 15mA or 20mA coming in tube ?

any thoughts?

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[Dean448]

Lasers because of the voltage are dangerous to diagnose without equipment and training. You could check the the red wire connection to the tube. The wire and post from the tube must be clean and solidly connected. Don't solder. I put silicone all around the joint.
The only other check would be that the PS is getting a signal up to 5 volts.
If all this checks out I would replace the tube before the PS. But that's a complete guess and also a spare tube wouldn't hurt.


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[lukahr]

yes i have first checked that, but it seems that connections are fine, i have also measured signal input into psu and it gives right voltage 0 at 0% and 5v at 100%. Its just weird to me that amperemeter shows max 1mA of current on tube (measured on thin wire at the tubes beam exit) even at 100%, is that possible if tube is broken, or it would show normal current somewhere around 20mA at 100%. is there a way to test psu without tube?

[fixtureman1]

take a look at this site for testing

How to test and set a Chinese (China) made CO2 Laser Power Supply to get long life from your CO2 Laser Tube for your Laser Engraving and Laser Cutting Machine System

[Dean448]

Because of the danger I wouldn't attempt it without proper equipment. You say you ran ten hours. At what power levels? Also is the red light on the PS bright and solid? I still guess tube because if the PS were bad it wouldn't work at all. At least that's what I would guess.
That link above is about setting up a power meter not testing the PS without a tube


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[lukahr]

take a look at this site for testing

How to test and set a Chinese (China) made CO2 Laser Power Supply to get long life from your CO2 Laser Tube for your Laser Engraving and Laser Cutting Machine System

i have tried that but my power supply doesent have any potenciometer for setting current, at least i cudnt find it, so current is always 1mA, i'll take picture if you guys will know how to set current higher.

Dean448 yes the led light on psu is solid bright. With 10 hours of on tube i mean that laser is actually new, 10hours of cutting all together. My cutting engraving jobs are max 30-60 minutes engraving at usualy 15% and cutting sometimes at 100% but that is max 10 minutes together so i doubt that tube would be empty its almost impossible.

[fixtureman1]

If you are cutting at 100% power then it is the tube

[Dean448]

I don't know what 100% means but 15 ma is pretty high for a 40 watt tube. Assuming it was close to 40 in the first place. If you can't live with 80% of your old power level then you may want to look into a better unit. Or upgrade the PS and tube if that's possible. You sound pretty technical, you could even build a unit from scratch.


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