Laser faded through cut and now wont fire

Quote from matt gorse on December 8, 2020, 9:23 pmHalf way through a cut the laser failed. Looks like it faded for a few seconds and then turned off.
The fan had failed on the power unit so I replaced this anyway assuming it was this.
New power unit in and the test fire on the power unit works but nothing from the gerbil.
Checked all wires and reseated big connector. Earthing is all good.
Any idea's?
Half way through a cut the laser failed. Looks like it faded for a few seconds and then turned off.
The fan had failed on the power unit so I replaced this anyway assuming it was this.
New power unit in and the test fire on the power unit works but nothing from the gerbil.
Checked all wires and reseated big connector. Earthing is all good.
Any idea's?

Quote from matt gorse on December 8, 2020, 10:36 pmjust to confirm. New tube. Doesn't fire from lightburn. does fire from the power unit.
just to confirm. New tube. Doesn't fire from lightburn. does fire from the power unit.

Quote from Paul on December 9, 2020, 11:52 amHi this usually happens when the laser tube wears out. Some tubes last 1000-1500 hours but I had my first K40 with about only 300 hours lifespan :(The reci tubes do way better than the K40 stock tubes.
However your case seems to be different. You can manually wire the LO signal via a switch to ground and test run the system while flipping the switch. If this works then the mini mosfet on the MG board is defect. If this does not work then we need to look at the PWM output transistor. Hook up a pot of 5kOhm across the +5VDC, IN (whisker of the pot), GND pins on the K40 stock Power supply. If that works than either the PWM wire connection is broken or bad or the PWM transistor is defect.
After these tests, let us know your findings and if defect we replace the board within the warranty terms.
Cheers, Paul
Hi this usually happens when the laser tube wears out. Some tubes last 1000-1500 hours but I had my first K40 with about only 300 hours lifespan :(The reci tubes do way better than the K40 stock tubes.
However your case seems to be different. You can manually wire the LO signal via a switch to ground and test run the system while flipping the switch. If this works then the mini mosfet on the MG board is defect. If this does not work then we need to look at the PWM output transistor. Hook up a pot of 5kOhm across the +5VDC, IN (whisker of the pot), GND pins on the K40 stock Power supply. If that works than either the PWM wire connection is broken or bad or the PWM transistor is defect.
After these tests, let us know your findings and if defect we replace the board within the warranty terms.
Cheers, Paul

Quote from matt gorse on December 9, 2020, 10:01 pmThanks for the info. The tube was recently replaced and when I test fire from the power supply it works fine.
Sorry I'm not too hot on the technical aspects of your instructions.
So I ground the lo (white wire) coming from the MG board. Then turn the machine on? That will make it fire?
I think best to do some basic tests and then if it needs any more diag I will post the item for you guys to look at it.
Thanks for the info. The tube was recently replaced and when I test fire from the power supply it works fine.
Sorry I'm not too hot on the technical aspects of your instructions.
So I ground the lo (white wire) coming from the MG board. Then turn the machine on? That will make it fire?
I think best to do some basic tests and then if it needs any more diag I will post the item for you guys to look at it.

Quote from Paul on December 11, 2020, 12:29 pmHi Matt, the tests are for the k40 unit with MG disconnected. If in doubt let us know and we will help you further.
Hi Matt, the tests are for the k40 unit with MG disconnected. If in doubt let us know and we will help you further.