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

Picture of 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
Be safe when performing this project.


The high voltage laser power supply settings can greatly affect the lifetime of the CO2 glass laser tube.  A setting above 30 mA will, in almost all cases, greatly diminish the operational life (changing an expected life of several years to months).  Even though the laser tubes are ranked in months, such as the 60 watt tubes, I have had customers use them for years before they finally loose power.

More recently, the higher power CO2 glass laser tubes, above 80 watts, and certainly 100, 130, 150, and 180 watts have been more inclined to have shortened lives because the power supply is improperly set.  For example, I had an unscrupulous seller who sold me a 150 watt laser with a power supply set at 34 mA.  My Mahoney laser power probe measured 145 watts.  Then, I contacted the seller because my multimeter read 34 mA.  His engineer said the power supply should be set to 30 mA for full warranty on the tube.  After setting to 30 mA, I measured the laser output power and got 129 watts.  Then, I contacted the company and returned the laser because the seller had actually sold me a 130 watt laser with a 150 watt price tag.

Whatever your reason for checking the power supply current, the steps are provided to demonstrate a safe manner to take a reading then take action to remedy.
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Ragged Edge17 days ago

Really nice article. Thanks for the power supply information. First insight as to what might be wrong with my machine.

I purchased a new 150 Watt laser 3 months ago. (Chinese 37 X 48" bed, purchased through a U.S. Company. Tube says 160 watt) I have been very pleased with this machine (and the company I bought it from) as it did all that I had expected.I really like this machine for what I bought it for (Cutting shapes into 1/16" rotary cut maple veneer) and all the other projects I have been thinking up. Amazing machine!

From day one the machine has reflected some of the tube energy off the splitter mirror, onto the back case when running. This easily burns through masking tape placed on the case. Company said this was OK.
Two weeks ago it stopped cutting properly at the speed and power I normally run it at, speed 80 and a power of 100. After testing I would say it is almost half as strong as when I bought the unit.

What I have done to try to solve the problems:

- Leveled the bed of the table. It was slightly out and now has a consistent level over its entire surface.
- Changed the lens at the cutter nozzle and made sure they were clean.
-Removed, tested and changed the splitter lens at the ruby red laser, just in front of the laser. (did not help the burning on the case)
-Aligned all the mirrors correctly and cleaned.
-Tested the power supply with the equipment and instructions provided when purchased. (big resistor n such) Lots of power.

The unit has a mA meter built into it. When I first bought the unit when running at 100% power it would read around 40 mA now it will not go over 10mA when running at the same settings but the power supply test seemed OK.

This week the tech told me I should never run the laser at 100%. This was news to me as it is not in any literature I have gotten from them and when I first was setting up the machine tech support said nothing about this. We have a similar sized machine where I teach and they always run their machine at 100% without ant problems. Now I read your article!

My questions are;

Where did the mAmps go when the power supply test says it is OK?

Is it normal to have reflected energy from the beam splitter hitting the back of the unit?

Is it wrong to run it at 100% power? It does not run continuous during the day when in use.

Any insight on my next step from the form would be great as I am running out of Ideas.

Thanks for listening.

How do you measure the laser output power?

laser_power (author)  paul.kirkpatrick.919 days ago

Used the Mahoney CO2 laser power probe. There are videos on youtube showing how it operates.