Question:
My k40 (C3D) just stopped working in the middle of a job. The head kept moving, but no laser action. The water pump is running and the temperature is good. The exhaust is working as it should.
I can control the movement of the laser head as normal, but the laser is not firing.
What would you reccommend for troubleshooting…? How can I figure out what has happened…?? Everything was working and then not.
Kind of desperate for input, thanks for any help!
Sounds like a dead laser tube to me, can you fire it from the test button?
No response when I push the test button…
Is that normal that a tube just suddenly dies like that…? I was expecting it to slowly fade away.
no interlocks on the protect loop that are open? im sure you checked but you never know…otherwise i’d think dead tube also. Does the tube illuminate at all? does it mark a label or piece of paper at tube exit/first mirror?
It could be your psu also but I’d put money on the tube as that’s the more expensive option and that’s how things work unfortunately
I have not checked interlocks on the protect look. What is that…? 
It does not leave a mark on anything at the first mirror. I cannot see it illuminating either.
Interlocks will be any safety switches you have in place (e.g. to prevent firing if the main lid is open, the tube lid is open, the water is not running, etc). If you have them installed, one of them may be faulty & triggered saying that a lid is open when it’s actually not.
if your machine is using the default control panel then the interlock loop is your “laser on” button. and no illumination will happen if this loop is not closed, otherwise I fear a dead tube…
Yeah, as far as I can see the laser on button should be working as
normal…
So…someone on Facebook suggested I test the L wire. So I did. And I am confused. Can someone explain to me if this is right:
It has a constant current of 4V (when not being used). When I press the test fire button, the current drops to 0.
Does that make sense to you?
yea it does, the Laser PSU fires when L is grounded, driving it to 0v.
Picture of supply please?
@donkjr sorry for the delay. Here is a pic of the PSU.
@Andreas_Benestad Have you tried:
With the laser switch on
