Co2 laser problem, electrical discharge sound, too much power.

[Pauchuk]

Hey. I hope this is the right section.

I bought a second "red and black" 130w co2 laser. First one is running fine, all good.

The second one - At some times I hear electric cracking noise, discharge somewhere near tube.

The first machine does perfectly engrave at 150mm/s and 9% power (mat finish, perfect).

The second machine even on 500mm/s and 9% power does engrave at least 0.5mm deep.

Both machines are supposed to be identical..

Any suggestions appreciated. Thank you in advance.

[Pauchuk]

Update: So, cracking noise gone by itself and there is a little switch on tube PSU which enables power control.