K40 not engraving, power issue?

k40-power-supply
(Nathan Thomas) #1

Hello all,

Looking for some help on this power issue I’ve been working on sparingly for the past few weeks.

Suddenly my k40 started giving out as far as power. I didn’t hear the normal hissing noise I’ve heard some speak of. I had to increase power to get things done until now there’s no more power.

At first I thought it was the laser tube, but I replaced it and still no power.

Then I aligned the mirrors and they are aligned. I get a strong test dot into the tape to the first and second mirrors…but it’s very weak at the mirror on the laser head. I have to hit the test switch up to 10x’s at 50% power for it to appear. When it does, it shows that it’s aligned.

I always use fresh distilled water with a little bleach, so that’s not an issue.

I’ve followed Don’s test pdf (which is genius) but get to “K” and then “R”.


The L signal is not wired correctly from the controller
• The controller is not configured properly for the port being used for PWM (L)
• The controllers PWM configuration is not correct
• The Laser module in the configuration is not enabled.
• The job is not sending anything to the controller
• The S value is 0 in the gcode.


I’m not sure which of these things I should check or that would apply to me because I haven’t made any modifications at all to the machine or the supply. I’ve used this machine pretty much problem free out of the box until recently.

When I do run a job and look hard, I can see a very, very light engraving very lightly scratched on the surface.

Suppose it’s possible I could’ve gotten a bad laser tube from ebay, but I’d still like to proceed in case that’s not the case. How would I test that anyways besides spending money on another…

Any help or ideas would be greatly appreciated

(Don Kleinschnitz Jr.) #2

Please post a picture of your LPS.

Since you are getting some power but not full power I am assuming the problem is your LPS.
If you have done all the tests in the pdf that got you to “R” I assume the LPS is wired correctly and the external controls are working properly otherwise you would have found a problem before R.

Before we conclude you have a bad LPS lets check the final lens and mirror.

Common problems are

  • The last mirror is damaged
  • The lens is mis-positioned, cracked or dirty.
  • The beam is hitting the side of the lens tube

Post a picture of the beam (on a sticky) going into the head and at the correct focal distance on the bed.