Laser Starts then turns off. K40 Cohesion3D LaserBoard

To make sure we are on the same page:

With the power set a 50 or 100% when you push the LPS red test button the laser does not fire but the red led on the LPS turns off while you are pushing the button?

Does the LED turn off/on when you push the button and then come back on again or is it now constantly off?

In the LPS picture above:
Where does the black pair of wires that is connected to the left 2 pin white connector [P+G] … go to.

Don
The LED light stays lit. When I press the test button it also stays lit. It does not blink or flicker.

I guess I stand corrected. I do have a flow sensor. the 2 black wires go to the flow sensor.

Here is the picture of


the flow sensor

now I’m lost?? What am I missing?

Laser just stopped firing.
Before it would fire for 1 second and now it won’t even do that.

With the machine powered up is the LED on the LPS on or off?

With the machine Powered on the LED is ON
When I push the test button the LED stays ON no blink or change

The problem is most likely a bad LPS… Less likely, but it also could be the tube.

We can check the inputs on the LPS to see if there is anything wrong with the controls to the LPS but to do so we have to make some DVM measurements. Do you feel confident doing so?

Would the LPS just go out?
I have been worried about the tube going out because I never new how to keep track of how long I used it.
Even if I did I don’t think I would have known how old the original tube was when I got it.
Is it easier to replace the LPS then run the tests?

These LPS are the most common failure item literally like a consumable.

How old is the machine?
How hard do you run it?
What type of coolant are you using?

Earlier in the thread, you mentioned overheating. Why did you think it might have overheated?

I was cutting some wood but not for longer than normal.
I typically have used the machine to engrave.
This has been the 1st time I have used it to cut and noticed the water run hot.
I replaced my normal gallon water tank with a 3 gallon one and waited for the water to cool down.
And here is where we are now.

The machine is a couple of years old but I only use it as a hobby. I run it once every couple of months or so.

@Jose_Padilla we can’t stress enough that owners of K40 laser cutters read the K40 Intro front to back and understand what’s mentioned in it before running their K40 laser cutter. It’s a bit late for your machine since it sounds like you ran it quite hot and over the recommended temperature for an extended period but here’s the link from the K40 Intro which talks about cooling the laser tube:

BTW, the K40 Intro page link is located at the top of this very page and can bee seen if you scroll to the top of this forum post.

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@dougl thank you for the education. I tried to keep the temp down this is how I knew it was getting too hot.
Is there a way to test to make sure it it the Laser tube that is done vs the LPS?

Don would know the best ways to figure out which is likely the primary failure. BTW, another site with a great FAQ list(one which I read front to back before purchasing my K40) is on this site: https://k40.se/

As to your question about if it’s easier to replace the LPS vs test the LPS there should be a number of HowTo’s on replacing the LPS on a K40 with the most difficult aspect likely to be the splicing of the HV wire into the existing wire so you should be able to ascertain if you’re up for that, otherwise it is more or less a drop-in reconnect-wires type of replacement.

Well at this point I guess this was a good starter laser. I will look into seeing if I can sell it for parts.
Any recommendations?

Laser Power Supply and tube are both consumables in a K40. The first recommendation here is to replace them.

Next recommendation is after replacing them (or using this as an excuse to get a bigger / more powerful laser, or whatever) is to read all of Getting Started with CO2 Lasers since that has lots of hard-won knowledge. :smiling_face:

If you want to spend extra on a new laser instead of just replacing two main consumables, why not spend extra on a proper refrigerated water chiller with an alert that will stop the laser if the temp goes too high?

Thanks for the recommendations. Based on my use. I think I am switching to a Diode Laser.
Any recommendations?

of interest: did you actually measure the temp of the tube.

What do you mainly want to do with your machine?

I mainly do engraving and family gifts….
I was going to start doing some wood clocks but I can always look at alternative material.