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.

Step 1: Do not touch the red wire.

1. Power off laser machine
2. Wait ten minutes. this is the time for the power supply to drain power from its electrical capacitors. 
3. Setup as shown in photos below.  You will need to purchase and use two sets of wires.  We recommend a black wire with aligator clips on each end and a red wire with aligator clips on each end.  These wires should be available at radio shack.

          A. See the power supply wire connection.  Do not touch the red wire.  It has extremely high voltage that is lethal.

          B.  See the thin wire.  It is colored blue, or black, or green as shown.
Hi have just set up my new 60w chinese laser cutter and thr interface on it is in chinese and when i try the pulse button nothing happens and error message comes up in chinese. Ther does not seem to be any pwer going through the laser tube not sure what to do next any ideas.
<p>Hi </p><p>I recently purchased a 40W co2 Laser Power Supply(ZR-40W), but it has only one output wire(red). I don't know where to find the negative connection.</p>
<p>Any success? I have a similar power supply - please help!</p>
<p>Check these</p>
<p>There are four terminals FG, AC, AC, L(-)</p><p>FG- Earth</p><p>AC- Phase</p><p>AC-Neutral</p><p>L(-) - Negative supply for laser</p>
<p>hi i've repaired many laser power supplies both output wires comes from HV transformer it seems from the picture that the other wire is one which is insulated by a tube wherever that one is connected you can solder other prob from there</p>
<p>Hi everyone</p><p>Three years ago I began using a laser tube machine.<br>The CO2 Laser tube worked perfectly well for three years.<br>But recently I started having problems, even with the new one.</p><p>So far I had no idea what might be the problem but, thanks to this article, <br>now I know that the power supply can be the principal cause of the CO2 Laser Tube Problems.</p><p>I also have a very important fact to share.<br>Our laser machine includes a power booster,<br>which doubles the current from 110V to 220V.<br>But guess what? The cables were inverted inside the power booster box,<br>and therefore, when we thought the machine received 220V, it really gets only 110V. But we solved the problem.</p><p>Thank you all for your comments.<br>They've really been helpful for me.<br>Success with your projects.</p>
<p>You mention being safe electrically when working with the laser power supply. Its also important to be safe with the laser optical output. An Infra Red Laser poses an extreme danger to the human eye. At my last job, we were required to wear protective goggles when in the room with an operating class IV IR Laser. Even when the tube was in its protective optical enclosure. Working on an open CO2 tube without goggles, without a plan for where the optical energy from the working aperture is going, and any leakage from the back mirror is going, and an IR scope to determine if there is any other optical issue, is an easy way to go blind.</p>
<p>wow thank you for your post, once i read that some reci tubes were modify the tag but i think was only a urban legend now i know its true! THANK YOU, REALLY!</p>
<p>Really nice article. Thanks for the power supply information. First insight as to what might be wrong with my machine.</p><p>I purchased a new 150 Watt laser 3 months ago. (Chinese 37 X 48&quot; 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&quot; rotary cut maple veneer) and all the other projects I have been thinking up. Amazing machine!</p><p><br>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.<br>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.<br><br>What I have done to try to solve the problems:<br><br>- Leveled the bed of the table. It was slightly out and now has a consistent level over its entire surface. <br>- Changed the lens at the cutter nozzle and made sure they were clean.<br>-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)<br>-Aligned all the mirrors correctly and cleaned.<br>-Tested the power supply with the equipment and instructions provided when purchased. (big resistor n such) Lots of power.<br><br>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.<br><br>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!<br><br></p><p>My questions are;<br><br>Where did the mAmps go when the power supply test says it is OK?<br><br>Is it normal to have reflected energy from the beam splitter hitting the back of the unit?<br><br>Is it wrong to run it at 100% power? It does not run continuous during the day when in use.<br><br>Any insight on my next step from the form would be great as I am running out of Ideas.<br><br>Thanks for listening.<br>Ted</p>
<p>How do you measure the laser output power?</p>
<p>Used the Mahoney CO2 laser power probe. There are videos on youtube showing how it operates. </p>