Co2 K40 Laser newbie, dead tube? or dead power supply?

I just received my monport k40. It looks like the carrier was pretty rough with the handling. The chasis was dented and the X gantry was warped to the point the belt was rubbing against slider of the linear rod. I was able to un-warp it and fix it.

After setting up the water cooling and trying to fire the first pulse, the laser did not produce a pink beam inside in the tube, also failing to burn or even darken the tape I put on the first mirror.

The LCD shows:
Water Protection: ON, which is ready
Laser signal: ON, when pulse is pressed
Ammeter: 0 mA, always, no matter if knob set to min or max

Looking into the control chamber, I noticed pulse tests make the fly transformer arc like crazy. It was arcing 3 ways, between PSU chasis, fly transformer, and the 3 wires between the PSU board and the fly.

I tested a fix by unscrewing the fly and letting every sit further apart. No more arcing to the chasis, or the 3 wires. However I still see arcing inside the gaps in the fly’s core.

All the while, not a single sign of life from the tube.

My question is this:

  1. Is this a dead PSU? or the PSU is fine, but a faulty tube that is causing the PSU to arc? What do I test next to find out?

Got it in one!

I highly recommend filing a claim with the seller for concealed shipping damage. Unfortunately, both the seller and the carrier will blame each other, while simultaneously telling you there’s nothing either can do because you accepted the shipment.

IMO, given your description of the damages, that machine arrived as scrap and will never work correctly.

For example, the difference between a bent linear rail and a good linear rail will not be visible to the unassisted eye, but a bad one will wreck the machine’s performance.

As the river said, my sediments exactly.

When you get it, it should work.

I hope you took photos.

Welcome to the site… sorry for the news :face_vomiting:

Good luck


  1. Dented PSU chasis, the picture doesn’t show the back near the flyback transformer. It’s completely crushed
  2. Dented body on front left of overall chasis
  3. Crack on left of tube
  4. Glass shards on bottom of right side of tube
  5. (I fixed this, no photo from before) The gray metal supper under the linear rail was warped, tilting the whole motor and 2nd mirror support down by about 15 degrees

Yeah, you got yourself a pile of junk there.