K40,MKS board, Lightburn Problems with power after board replacement

Hi Oz,

Having a slight problem, I was given a K40 brand new and thought I would have a play and I took advice and was advised to pick up a MKS board as the mid range priced board to enable lightburn to work.

Prior to Installing the board it had a Nano board that comes with the K40 and I used Whisperer for a few days while I waited for the MKS board to arrive.

I was having no problems at all with Whisperer and power and I was getting 16ma easily and could have gone a lot higher. But I want to use Lightburn as that is what I use on my diodes.

Now I installed the board with the help of another K40 user who has the same board and talked me through all the connections and the board works, everything is ok apart from one thing and that is Power

I can not get the Milliamp meter now to go above 7 amp absolute maximum. We have tried a number of things such as different computers, etc, we are running the latest version of lightburn, lightburn is working perfectly ok apart from the power level,. we’ve set the power levels in lightburn right to 100% and get an additional 1 milliamp.

On my friends machine his power level is fine and I have exactly the same board as him and the config file. To be honest I am now not sure what to do, as part of the test I removed the MKS board and put the Nano back in and got 16 MA back again , I tried turning the POT up before removing the board but that makes no difference. Both machines are exactly the same K40s the PSU, Nano board, cabling etc all the same. even the tube.

So now I am stuck and am looking for some ideas please.

I have a few days left in which to send the MKS board back and am not sure whether to do that and buy a mini gerbil , I don’t need 3 axis. The tube looks ok as I was getting the power before & still on the nano.

All the Mirrors and tube are aligned perfectly. I followed a K40laser Tutorial and shimmed and adjusted it all and on whisperer in the toal bed area I was getting perfect cuts using the Pot.

I am not sure what to do or where to go now and I am looking for some advice please , I run my lightburn on windows 10 on a bootcamped mac mini running mojave and latest bootcamp, to be sure it wasnt the Mac I also checked it on a Windows 10 laptop and the result was the same no more than 6 milliamps.

Could I have some words of wisdom please, pointers, etc, I am now at a loss. I just dont want to go back to whisperer, its horrible after having lightburn for 2 years on my diodes.

Thank you. Neil

Here is a link to see the tube working https://youtu.be/v2IYU8tipSM

Attached is the config.txt file

config.txt (25.3 KB)

Have you tried tweaking your friend’s settings under “## Laser module configuration” section?
we are dealing with a mix of digital and analog regimes - not all tubes and power supplies are the same. you might want to tweak these settings and see how they effect your system power/mA:

  • laser_module_maximum_power
  • laser_module_pwm_period

you have these set to 0.8 and 200 respectively.
Try lowering these down a bit - like:

laser_module_maximum_power 0.5
laser_module_pwm_period 100

And see if your power goes up for the same lightburn power settings in %.
This should be safe to do but as with lasers - always stay protected and safe.

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Thank you I will give that a try later, many thanks.

Increasing the PWM period sometimes helps - certain power supplies don’t like being PWM’d quickly, but that also shouldn’t have any affect at all if you’ve set the output to 100%.

On the other hand, the config file is showing only 80% power maximum allowed:

 laser_module_maximum_power                    0.8

Change that to 1.0 to allow 100% power output.

1 Like

thank you for that.

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