Charred cable connection to laser tube

120w Ruida system. Started cutting small project just fine and suddenly laser stopped firing and air assist stopped assisting, head still moving as if nothings wrong. I opened the back of the machine and see badly burnt cable insulation where two cables were connected via a spade type connector; this is the red cable that leads to one end of the laser tube (positive I assume) . Suspecting it was probably a poor crimp connection from the factory I stripped back the wires and reconnected with new spade connectors. I plugged the laser back in and ran a small file and the new connection immediately burned through…any suggestions where to start the diagnosis?

Can’t use regular connectors on HV. Most of the time they are a set of screw terminals and a wad of silicone inside a silicone tube scrap.

Thanks Dave, I just came in from soldering that connection and trying again. Good news…sort of. Everything works but power from the laser seems to be way down. I was previously cutting this file from 1/8" Baltic easily in one pass. Now I can’t get through it in two passes at 65 percent power. FWIW gauge is showing output is 32mA. Could the tube be failing? Would that have contributed to the connection overheating?

Can’t speak to a failing tube without an actual power measurement. The HV wire doesn’t solder all that well, It usually has a mechanical connection. You may have soldered it, but I would suspect electrically you have the equivalent of a cold solder joint. Personally I would take a twisted and wire nutted connection over a soldered connection on the HV side. Either regular wire nuts and stood up away from everything else, or drop by the farm store and pick some up in the electric fence department. Some regular wire nuts will work for HV, others won’t and I don’t know the difference to be able to tell you. I just use a screw connector and some silicone in a scrap of tube.

As for the current, my current jumped when I had an overheated tube, so it is a possibility, but until I had a good HV connection I wouldn’t trust that reading.

Thanks for the replies…back up and good as new. Laser tube and power source operating just fine. I did a thorough cleaning of the machine and discovered a cracked and burned lens; I’m wondering if that could’ve somehow been a side effect of the laser power lead shorting to the chassis???