Intermittent "squeal" from somewhere in the cutter

[ewa_taylor]

I am having the same problem as ScrappyJedi. I ordered a new tube (40w 850mm) and it has the same squealing and "bending" of the plasma as shown in the videos in this thread. I'm reading a maximum of 20ma off the tube's return wire to the power supply, and have tried it at a variety of powers below that.

This was the same problem the tube that came with the machine developed, so after seeing the same probleem with the new tube I was thinking it could be the power supply. But now I've read this thread and I'm not so sure. Has anyone had similar problems in the past and solved them?

I have a new tube on the way from China (I ordered it before ordering the replacement from LightObject, which I ordered after seeing the shipping estimate from China) so that should narrow things down a bit.

Thanks for any help!

[Tech_Marco]

I am pretty sure that it is a power supply issue. (not really a big problem).

I have tried a few tubes; 35W,40W, 60W, and 80W on my tests All tubes generated some "squeal" sound . It was just matter at what current level.Some happened at 2~3ma some happeNed at 8~9 ma. It was due to the structure of transformer and the power rating of the tubes.

I also tried a bunch of PSU and none could escape from that symptom. Accidentally, I blew a DSP card for one test!

Melissa, I did try PPI and no PPI on your returned tube
It worked great. I could do both engraving and cutting
PPI could show less power and you need to raise the power on Max current set up

I was using speed 30mm/s speed and 600PPI. The I used 400~500mm/s on engraving. Power was set 15% and 20%, roughly reflecting 5ma current. I could hear some sounds when burning but it cut clean in cartoon paper
Also, I could cut through 6mm pine wood at 8~10mm/s at 18mA

Today I will do one more test: let it do cutting for over 10min. with and without PPI. If no brokn line happened, I will return the tube to you.

Marco

[Tech_Marco]

Testing update:
The process took over 16min to complete. I didn't see any missed fire or abnormal behavior.
The tube is great with very fine laser beam spot

http://www.youtube.com/watch?v=2IeXmA3lmGA