Replaced laser tube, cutting power still reduced

[JimRiehl]

I have been using the 40w PR530 for the last 18 months or so. Even with regular cleaning of the mirrors and lens there was a slow reduction in the apparent cutting power of the machine and I have made minor tweaks to the power and speed settings over that time. Recently the cutting power dropped dramatically and I decided to replace the tube (LO SPT 40w). I also cleaned/realigned everything, leveled the bed, and verified the focus.

I expected the laser to return closer to its original state but it only made a slight difference. Is there anything else that I may be missing that can cause this degradation over time? Could it be the power supply?

The power supply appears to be working, ammeter read is consistent when cutting and at the expected mA level. Engraving quality is on par with how it has alway been but I mostly cut 1/8" wood. I also do all the settings on the computer and don't modify them from the controller.

Any help would be much appreciated.

[Tech_Marco]

This is due to the miss-alignment or bad focus point. You may also need to clean the beam combiner (red dot + CO2 beam) as dust on top of the lens could cause power drop. Mirror & lens may need to swap once a year depend upon usage time on the machine

Marco

[JimRiehl]

Thanks Marco! I will double check the focus, alignment is good at all 4 corners. I also replaced the mirrors and lens a few months ago, but I did not clean the beam combiner recently.

If there was an issue with the power supply would you expect degraded performance or just straight up failure? Seems like a component that will either work or not.

[Tech_Marco]

If you couldn't get enough current like 15mA at full power (65~75%) from the PR530, but getting something like 10mA or lower, that may be a defective LPSU since you have a new tube. A bad LPSU could be totally dead or it could output 1/2 or 1/3 current due to partial transistors burned

Marco

[JimRiehl]

Great to know, thank you. Seems like the PS is just fine but cleaning the combiner seemed to help a noticeable about.

For the focus, is there a set dimension on the PR530 head that I should be using to make the focus spacer? For example, is it right at 30mm from the bottom of the lens to the tip of the nozzle? So the spacer needs to be the lens focal length minus that 30mm?

I don't recall how I made the spacer I use but it may have been guess and check and I still may be off a bit.